Some of this terminology seems useful for talking about consciousness (which I suppose is a sort of psychiatric condition); there’s obviously a useful distinction between humans and algae, but trying to pin down an exact dividing line proves difficult, especially when you entertain thought experiments like removing one neuron at a time from a brain. Lots of debates about e.g. animal consciousness seem possible to phrase in terms of the shape of this graph. See also the Sorites Paradox.
My take on that has always been that while categories such as "heap" are not *necessarily* defined with objective cutoff points, if it makes sense to define it anywhere, it'd be the point where the grains/articles of object are stacked in a pyramidal or conical configuration. So the fewest possible grains of sand that could constitute a "heap" would be four- three arranged in a triangle and one on top. In practice, unless you arrange them very carefully, with tweezers or such, four grains are unlikely to constitute a heap, because if you're pouring them onto a surface, you should expect it to take a lot more than four grains before any of them achieve a configuration more than one layer deep.
How many layers does your pyramidal configuration need to count as a heap?
I feel like this misses the point. The common parlance of 'heap' does not include any definitions about pyramidal configurations or anything else. I believe the truest definition of "heap" is anything that pattern-matches to a heap for most people.
Sorite's paradox is pointing out that there's no 'correct' cutoff for these categories along a spectrum. Which is exactly what Scott was pointing out.
> The common parlance of 'heap' does not include any definitions about pyramidal configurations or anything else.
Probably not pyramids per se... however it is not unreasonable to expect a 'heap' to involve things heaped on top of each other, which do look like that in minimal form. As suggested in their bottom line, the point is that a single layer is certainly not a heap.
But you're also right, the point is a reference to a paradox about a Greek word, and it has no obligation to work anything like the English word 'heap' we translate it with; if that's a property of 'σωρός' that's lost in translation we can still understand the idea being represented.
Category boundaries exist but are fuzzy. No, there's no fixed number of grains we'll all agree on as a cutoff for using the word, "heap," but you could probably define a numerical metric of "heapness" and we'd mostly agree on its shape. There would be a minimum of 0 heapness at 0 grains, and maybe another 0 heapness at "enough grains to form a black hole, or at least enough to become spherical under its own gravity." There would be a maximum, determined by combining many people's judgments, maybe somewhere near human height.
This also applies to many "alignment charts" or discussions of "what is a sandwich, really?"
I think this arises when you take a dimension and apply it to a category. Heaps of sand isn't really an issue as you don't treat a heap of sand any different from one grain less than a heap of sand, but in medicine there are dimension disorders with categorical treatment options, like gets the drugs/diagnosis or not, gets hospitalised/outpatient/nothing re treatment. I really annoys me when this is done for no reason, like with tax and govt transfers. There is no reason you need the bands since computers were invented we don't need the simplification of the math, you could just have a formula where the tax you pays go up faster percentage wise than your total income does. It could asymptote or have an s shape or whatever, it would need highscholl maths only, but with the bands people keep getting welfare cliffs and getting worked up when there income pops into a new band or the bands shift.
The simplest way to define the semantics of "heap" is to treat it as some function mapping entities in the world to (True, False): some things are heaps and some things aren't (you could add a third category called "Underspecified" or something, but this doesn't help much because you run into the same pardox at the boundary between True and Underspecified).
Given this background, there are a few approaches to "solving" the paradox:
1) Allow for uncertainty: even if "X is a heap" is treated as being something that "is" True or False for each pile of grains, language users who are asked "is it a heap?" will, as Bayesians, have different degrees of confidence that the answer is "yes", from 0% (definitely not a heap) to 100% (definitely a heap). It is maintained that objects are either heaps or not heaps, but knowledge of which category they fall into can only be known approximately. In this formulation, an observer could rationally be 80% confident that a particular pile of grains is a heap--perhaps even once they have all relevant information available to them.
2) Reject that "heap" is function that maps entities to (True, False), and treat it as a function that maps from entities to the range [0:1], just as you might for scalar adjectives like "full" or "dark". Piles of grains range from being 0% heapish to 100% heapish. In this formulation, an observer might be 100% confident that a particular pile of grains is 80% heapish.
3) Both of the above at the same time. Heapishness is scalar as in (2) AND knowledge about heapishness of a particular pile is only ever approximate. In this formulation, an observer might be 80% sure that a particular pile is at least 90% heapish, and simultaneously 90% sure that a particular pile is at least 80% heapish.
4) Define meaning entirely in terms of usage, instead of the other way around: "is a heap" is literally the same thing as "speakers tend to declare that it is a heap when talking about it (assuming cooperative, sane, competent speech)." It is meaningless to decide whether things " really are" heaps: instead, we only ever decide--a real-world practical decision--whether in a particular moment we would like to declare (to ourselves or others, and possibly in the context of a philosophical debate) that something is a heap, or to declare that it is not a heap, or to not make any statement at all as to its heaphood (which is by far the most common decision). Our choice of behavior (and thus whether or not it "is" a "heap") will be determined in some complex way by the number of grains along with many other contextual and psychosocial factors. In this formulation, if across history nobody ever spoken or thought about whether a particular pile is a heap or not, the question of whether it is a heap or not is literally meaningless.
For all of these, the relationship between number of grains of sand and heapishness, or certainty of heaphood, or likelihood of someone calling it a "heap", is probably something like a sigmoid function or "s-curve". You could if you wanted to find the number of grains where the y value is exactly 50%, but there's nothing particularly interesting about that number of grains, and the exact number will be affected by other factors like the color of the sand, who the observer is, how much coffee they had that day, and so on.
Personally I find (4) the most interesting, as it implies that the "meanings" of words are not dictionary-like definitions, but are real physical processes extended in space and time, encompassing the grains of sand themselves, light, our sensory organs and nervous systems, our cognition and memory, children's learning of language, and our moment-to-moment motivations for wanting to use language at all. Whether or not something will (or "should") be called a "heap" becomes the same sort of question as whether or not you will (or "should") put ketchup on your burrito, or drive to Seattle, or commit suicide--and just as complicated to answer.
With consciousness in particular, an obvious-to-me conclusion is that some people are more conscious than others. Since that *sounds* so bad, you might also say that the same person can be more or less conscious at different times (excluding the obvious: sleep).
Consciousness could very well be categorical. What if we define it, for example, as "are you thinking about yourself?." Then, you either are or are not conscious at any particular point in time.
(I think my father has some sort of strong opinion that this change was wrong and might have written an article about it somewhere, but I shouldn't be giving false information just out of family loyalty)
Oh, it's very arbitrary and probably will just result in more people using antihypertensives without increasing survival rates, but I guess the AHA sees value in scaring more people to take care of their cardiovascular health. European guidelines still use the 140 SBP cutoff
I suspect that the Number-Needed-to-Harm drops significantly with these aggressive hypertension definitions, especially as I see them being adhered to in cohorts where judgement should *definitely* be on person-centred basis i.e elderly care (without knowing the exact prevalence, my priors lean towards more elderly die from orthostatic syncopes and subsequent neck of femur fractures due to aggressive antihypertensive treatment than die from a SBP of 140-150...)
That was Freud's radical insight long ago, which the DSM initially rejected but is now slowly backing away from.
The problem is that the arbitrary cut off brushes under the table the suffering and impairment of those with subclinical manifestations - which is often similar to that over the threshold (1).
Once you admit dimensions, retaining simple categories is problematic. Particularly if one takes into account the absurd levels of mental illness co-occurence. If most with the flu also have a cold (removing the virus from the equation) - and a few with the flu have mad cows disease or strep throat or something else - and no one "in the wild" has just the flu - is the flu a separate meaningful disease?
After a while everything begins to blur and you're left with something like a p factor or some version of "problems of living". Which is likely for the best. We live in a world deeply hostile to any biologically sane way of life. Until we deal with that, we're just hacking at a never-ending stream of branches.
Does this article really signal proficiency in math? It mostly seems like it's arguing for a more useful way to think about categories vs spectrums. The most "mathy" parts are the statistical tests but Scott doesn't really explain how they work or what exactly they are measuring.
Understanding that sometimes numbers represent a measure of discrete categories and sometimes they represent a point on a spectrum is an important part of moving past a layman's concept of math, and seeing as MDs generally do a bare minimum of math (its nurses who transform a dose into an actual injection or rate) IMO this is raising the bar.
It's interesting that the most abstract form of math is category theory and category theory is, well, all categorical. Something either is or isn't an object of a category and two objects either are or are not linked by an arrow. Category theory subsumes all of math. Bartosz Milewski in his youtube course asks the question whether this reveals something ontological about the universe, or whether this merely reveals something about the way our brain work (he things it's the latter). If we are constrained by the structure of the brain to think categorically, rather than dimensionally, this sure does reveal why the human race is so plagued with tribalism.
Hey, aspiring category theorist and amateur mathematician here. I know this is entirely tangential to the discussion, but I don't agree with you on this. Certainly the definitions of what makes something "a category" are categorical (in the sense of the word used elsewhere in this thread), but that's true of literally every definition in math. If you don't specify exactly what your terms mean, then you can't expect other mathematicians to understand them in the same sense you do, and you can't write any formal proofs using those terms.
Tangentially, I'd also argue that category theory as it is practiced is not nearly as "categorical" as you are making it out to be; nobody ever asks questions like "is such-and-such an object in C?", and rarely do they ask questions like "is there an arrow X -> Y in C?" or even "is C a category?" -- they're much less interesting than questions like:
- "what properties does the category C have?" (e.g. does it have finite limits, finite colimits, infinite limits/colimits, a monoidal structure, a cartesian closed structure, is it a topos?)
- "what do these properties tell us about the internal structure of C?" (e.g. if C is cartesian closed, we can think of C as a C-enriched category)
- "can we infer properties of C from how C is related to other categories?" (e.g. adjoint functors preserving limits/colimits, adjoint functor theorems)
- "if we know what C is like, what does that tell us about other categories built out of C?" (e.g. slice category of a topos is a topos)
etc. I don't really know how to classify these kinds of results on a categorical/dimensional axis, they feel more like "building up a picture of what the field looks like" than "deciding whether something does or does not fit into Bucket X".
I'll leave the questions about the structure of the human brain or why humans are plagued with tribalism to someone who is more of an expert on those matters.
(I'm a long time reader of SSC, this is my first time posting! Apologies if this post is deemed unnecessary; but I hope it is both truthful and kind.)
I would call it mathematical (or statistical) literacy more than proficiency. Tragically even basic literacy is vanishingly rare.
My (non medical) PhD program long ago seems in retrospect to have been 3-4 years of dissecting peer-reviewed! articles in important! journals to diagnose where the authors violated assumptions, waved their hands, misrepresented their own data, and cherry-picked findings.
I work professionally in empirical studies now, and struggle constantly with colleagues and decision-makers who read the abstract (or only the title) and think so-and-so has been proven beyond dispute. (See also: problems with "systematic reviews" and "meta-analyses".) It is a huge problem with respect to policy & societal health/wellbeing (cf. the 'rona).
I don't think the article shows advanced Maths skills on Scott's part, but it does (as well as being extremely well written) show Scott's ability to communicate conceptual ideas - including mathamatical ones - with clarity and wit.
Scott himself has claimed numerous times he is bad at math. Of course bad by his standard is still above average, and more indicating that his math SAT section was below 600. He just worked his ass off to be statistically literate enough to understand scientific studies, even if he can't do any complicated math. This shows that nearly any doctor that took the time and effort to learn statistics, could understand this. There is just no incentive for an average doctor to put this effort in.
Well, if my doctor recommends something and I find a study that contradicts his advice, then it is not easy to have a conversation about the data with him. This has been true with all doctors I have seen through life, for myself or family members. Recent example, a discussion on hormone replacement therapy and blood pressure. They simply reassert their original recommendation. It just seemed like Scott here would be different and welcome a deep discussion.
In my experience, most doctors are working under intense time pressure, and are basing their recommendations on whatever it says on UpToDate. They may or may not be able to engage with you on the substance of the article you bring to the table. However, making a recommendation that is not supported by UpToDate (or whatever set of guidelines informs their practice) opens them to liability when you suffer a harm.
Matching a diagnosis with a treatment is definitely rule-based. I'm not asserting that this is a desirable feature of the current system, just trying to provide some context for why you might be having frustrating experiences with doctors.
"My guess is most professionals, and an overwhelming majority of laymen, are actually confused on this point, and this messes them up in a lot of ways."--how much of this is just reification as a crutch for computational efficiency given limited time/energy/attention?
The thought processes you are moving away from are simpler than the ones you are moving toward, and docs are pressed for time. Likewise, laypeople are mostly probably trying to make decisions about their lives with framings like 'I think that man may be a narcissist so I probably won't go out on a date with him'
The reifications have costs but also benefits and I'm glad you're digging deeper in your practice and inquiry. I worry somewhat about unintended consequences when categorical terms for dimensional characteristics escape the clinical setting and make their way into the ambient construct stew
As a side note, there are common categories in use for wealth like HNW, VHNW, UHNW, but they certainly don't capture the upper-end variation around someone like Bezos (for whom even 'billionaire' is off by orders of magnitude...)
I agree on a purely computational level categorical processes are similar, but practically they can be much harder. I know doctors who really obsess over whether a patient meets the criteria for bipolar, because they really need treatment, so they try to ask questions in a bunch of ways to figure out if a full manic episode that meets the necessary number of criteria really lasted three whole days or not. Whereas I just kind of get a gestalt impression that they were obviously bipolar, then treat them.
I would suspect it has less to do with computational complexity and more to do with communicational complexity, ie categorical diagnoses are easier to talk about and explain and teach, and therefore most people hear about these things in a categorical paradigm most of the time.
The next time someone asks me about my mental health I’ll feel tempted to tell them that I’m “the Jeff Bezos of absentmindedness”. For a while now I’ve intuitively been moving away from the taxonometric definitions of mental illness so it is nice to read something that really goes into the math of it. Even in the cases where there is a definitive “reason” for the mental illnesses listed in the study, like the flu virus for the flu, it usually seems like it’s either some kind of traumatic brain injury (difficult to reverse for now) or something genetic (impossible to reverse fo now) so holding out for a magic bullet is implausible... It’s all symptom management. But symptom management is often what can help someone get over the arbitrary-feeling “line” between “Person doing poorly” and “Person doing well”!
Thank you for this excellent article. I found the concept of a "resident of Extremistan" to be an excellent phrase for describing someone like myself. I fall into the 2% or less in seven major categories, including autism spectrum and bipolar disorder.
I just signed up here as a founding member after Jonathan V. Last at The Bulwark gave a recommendation.
Statistical question / hypothesis regarding substance use disorder:
Many analytic methods don't deal well with massing at 0 and/or 1 (whatever the boundary condition is). There are large proportion of the population who are teetotalers, and a small proportion of the population of drinkers drive a significant amount of alcohol consumption. I assume (probably incorrectly) that many substances have similar distributions of use per capita/time.
Question - wouldn't this bimodal distribution drive taxonicity in statistical analyses? Despite this, substance use is not cleanly divided in the clinical context where substance use is 1) comorbid, 2) often a coping mechanism, 3) not necessarily problematic.
It seems like language is biased towards categorical thinking - either you choose to use a word or you don't. You need to know from context that it's not what people really mean, that tallness is dimensional. Sometimes it's tricky to hint at dimensionality without being overly vague.
Yeah. I once tried to make a conlang, and one of the things I planned to include was a variety of "intensity modifiers" that let you turn adjectives like "red" into more nuanced constructions like "very red", "kind of red", "arguably red", "reminiscent of red things", "more red than you would think, given what it is", and so on, in order to address this very issue.
it's a decent test for an AI, to see if it understands that. Like if you give a GPT-3 chatbot a height and ask it to tell you "tall or not tall" I wonder how it does
Yes, isn't greater and greater specificity what language has always aspired to achieve? This is OT, but I've been trying to figure out if I'm turning into a cranky old maven who can't stand to see language evolve, or if we are indeed witnessing a rather remarkable period in history in which we are collectively demanding less and less specificity from it.
Social media is the most obvious catalyst for new expressions, but it also heartily embraces sloppiness of execution, asking consumers to intuit emotional meaning from fuzzy group reactions to imprecision. Is there any consensus about whether everyone who enjoys over-using the word "literally" is doing so with tongue in cheek or out of ignorance? Regardless, what is one to do when one really needs a word like literally? Do we have to say "literally literally," since "literally" now has a new cheeky/ignorant definition?
Scott calls the term IED an "acronym," while I always thought it was an "initialism"-- but now I see the dictionaries are allowing the broader definition, which I guess simply means not enough people care about maintaining specificity in this particular category. But I'm getting the feeling the loss of specificity is snowballing these days, like the melting of the polar ice caps. And we're already suffering some of the political consequences of this cultural evolution. Or maybe I'm just becoming a cranky old fart.
This would make an interesting new topic in DataSecretsLox. Here, I'm afraid, it has hit an already almost dead thread, and you'll get not much of a response. There are some smart (sometimes grumpy, but on solid grounds one can learn from!) old men over there (apology to everyone misrepresented!), as could be seen in the discussions around computer interfaces, so as crosspost should be worth it.
I think language isn't geared toward specificity. English especially seems to offer vagueness as a benefit. I think of "love" and its thousand plus meanings, or all the other words that have different meanings (another example being hot meaning temperature or spiciness).
Vagueness allows for tentative communication with plausible deniability (there was a discussion of this on SSC once, re flirtation, IIRC), and the everyday diplomacy based on it.
Hence the existence of a spectrum from scientific use of language (where every term comes with a well-referenced definition, in extremis: calculus) to fuzzy … let's call it 'sounding out of an emotional or affective resonance'.
Language does all that. We are the ones to be aware of what to expect/utter in what situation; and a misinterpretation of the situation tends to backfire in every way, from comical to meh to tragedy.
Is “person with autism” really misguiding? I mean, we already have and use terms such as “people of color”, or “people of size” and I don't think anyone really assumes those are binary categories.
For what it's worth, a lot of autistic people reject "person-first" language, though for different reasons than Scott suggests in the post. The problem with "person with autism" (they argue) is not so much that it's reifying autism as a clear category, but that it's presenting autism was something separable from oneself. At least that's how I understand it; my experience in the field is fairly limited.
"people of X" are in practice used to draw sharp categorical differences - color at least is. of size is probably more fat activists adopting general critical social justice lingo to get legitimacy for their campaign of destigmatizing slow murder.
“People of color” is a special case IMO. It’s a way to describe a non-white person without implying that white is some kind of default or ideal. And while “colored person” might seem to be a reasonable analog of “white person”, it has too much cultural baggage.
I think it does still imply that white is the default. It's also sort of like taking Lothrop Stoddard's view of race and concluding "That's basically right, just flip the normative rankings".
1. Why is CCFI of 0.5 chosen as the border between categorical and dimensional? In other words, it seems "being categorical" or "being dimensional" is itself dimensional - is this true?
2. Question about your practice (ignore if inappropriate) - comparing the post here and on your site, I see you've kept the personal tone, which surprised me. Did you get any feedback from patients/non-SSC-readers about the content there? It might be too soon to know, of course.
This is a great point (Scott Lawrence makes the same observation below, and his comments are also worth reading) but I think it's worth being careful to delineate the map and the territory. CCFI is a model. Even though a cutoff of 0.5 is arbitrary (so the model suffers from the problem of the heap) it doesn't follow that the distinction *out there in the world* is dimensional. It could be that "being categorical" or "being dimensional" is categorical, but given a particular case, we have to make a guess based on a dimensional scale because we don't have enough dimensions of data to fully separate the categories. Presumably the 0.5 hyper-parameter has worked reasonably well in the past for delineating cases like the flu.
I wonder if the positive feedback loop of addiction makes it categorical. "Propensity to become addicted to cigarettes" could be dimensional, but "is currently addicted to cigarettes" (or "has ever been addicted to cigarettes") could be more like separate categories, because it means "consumed enough nicotine for the positive feedback loop to kick in." How much that positive feedback loop affects you varies, but that's like variance in the strength of the flu which makes the "has flu" lump wider than the "doesn't have flu" lump.
Maybe also relevant that "how much nicotine would it take to set off the positive feedback loop" and "how strongly will the positive feedback loop affect you if it gets triggered" are strongly correlated (I imagine) as two aspects of "propensity to become addicted to cigarettes." So the people who are more strongly affected by that positive feedback loop are also more likely to have triggered it (since that takes less nicotine for them).
My personal impression of autism is that it's both. Aspergers seems to me to be more dimensional, whereas low-functioning Autism (for lack of a better term) seems more taxonic.
I dont have any particular study to back this up, its just more of a result of all the stuff I have read about Autism. Its probably also influenced by my belief that it might be wrong (for social reasons) to lump the two together into one diagnosis.
I think the major problem is that Aspergers is a syndrome, the causes are barely understood, and people whose symptoms are right in the middle do exist.
But still, to me it feels like having an unable-to-walk syndrome which includes everything from sprained ankles to loss of legs.
They are unable to come up with criteria that distinguish high-functioning autism from Asperger, but also high-functioning autism from low-functioning autism. That's why they gave it one label in the newest DSM.
In the past, the criteria for distinguishing HFA from Aspergers was based on history – if there was a delay in developing functional language, then HFA; if there was no delay in developing functional language, then Aspergers. That criteria worked about as well as any other criteria in the DSM does – sure, there were practical difficulties (history of childhood language development isn't always available for adults, the parents may no longer be around, and even if they are, their memories of decades ago may be imperfect), and as always there are problems with unclear boundaries (timing of functional language development is a smooth continuum), but nothing that rises to the level of "unable to come up with criteria". Honestly, I don't think the DSM-5 authors actually had a very good justification for many of their decisions, and I think those who criticise their decisions are in the right.
And if difficulties reliably distinguishing Aspergers from HFA justify merging the two conditions, well there are also difficulties reliably distinguishing ADHD from ASD. (A number of studies demonstrate the substantial overlap between the two conditions, where to draw the line between them varies from clinician to clinician, and the line has moved over time.) So if it is difficult to reliably distinguish ASD from ADHD, should we merge them?
It can also be difficult to reliably distinguish autism spectrum disorders from schizophrenia symptom disorders. In adults, they can present with quite similar symptoms. The most important way to distinguish them is look at history – if the symptoms were present in childhood, that suggests ASD; if they weren't, that suggests SSD. So, the distinction is based on history – fundamentally the same as the HFA vs Aspergers distinction was. If that's a justification for merging HFA with Aspergers, maybe it is about time we merged the autism spectrum and the schizophrenia spectrum too?
One of the things I love about this blog is how you pull meaningful conclusions that have fascinating real-world implications out of math that goes over my head (but is still interesting to read an analysis of). I went into this one taking a gamble that it would be interesting to me, and hit pay dirt at the end. Cheers :) and again, welcome back!!
Has someone does the analysis to determine whether psychiatric disorders themselves split into two taxa of taxonic and non-taxonic, or if they lie on a spectrum between the two?
This was exactly my thought. If you look at the CCFI figure, it really doesn't look like the distinction between taxonic and non-taxonic is itself taxonic --- it's more of a continuum.
Which... it /can't/ be, right? Either there's a binary hidden variable or there isn't. That's the strong intuition that goes with this distinction. So one of two things is true. Either that's wrong, and the distinction between taxonic and non-taxonic is itself pretty worthless, and we should acknowledge that everything has aspects of both. Or, the fact that CCFI fails to pick up on the obviously taxonic distinction between taxonic and non-taxonic is a hint that hey, maybe this isn't a very reliable measure.
To rephrase: the thing CCFI measures appears to be non-taxonic. Is that a really bad proxy for a taxonic thing, or is taxonicness itself a continuum?
I think taxonocity is going to be measured along a continuum. Warning: this is hyper simplified.
You could create a bimodal distribution with no overlap, to represent two distinct taxons, and then use a distance function to quantify the average distance a point in peak A and a point in peak B.
If you move those two peaks closer to each other, the distance function would decrease along a continuum even if you never actually intersected the distributions at all.
Now let's say you actually begin to combine the two distributions on the plot. At first, there are still two obvious different peaks (with some overlap as Scott pointed out). At some point these distributions would be largely indistinguishable and there would be some arbitrary "gray area" around which it's unclear whether the two distributions are categorically different or merely dimensionally different.
I agree that the "bimodalness" of a distribution is a continuous thing. But, "bimodalness" itself is at best a crude proxy for "taxonicness". Take the flu example above --- as Scott mentions toward the end of that example, if you actually look at a plot of flu symptoms, you don't see two peaks, so that "having the flu" appears to be a non-taxonic thing. Of course, "having the flu" almost certainly /is/ taxonic, and we'd see that if we plotted "density of influenza virus particles" or something like that instead. There really is some nearly-binary latent variable.
And in your constructed example, the same is true. You can make the distribution unimodal, but it's still the case that there is a binary latent variable. It just so happens that you've failed to see it.
So... I worry that that's what's happening with CCFI. For schizophrenia, for instance, people seem to believe (I know nothing) that it's taxonic. That means that the CCFI measure was just "looking at the wrong plot" (either literally or metaphorically, since I dunno how CCFI works), and that on a better plot, a beautiful bimodal distribution would become visible.
While I don't have time to read the whole thing now, I think this is a helpful part from the introduction of the paper Scott linked to, to begin to build an intuition for how this process works:
To reduce the subjectivity of taxometric analysis, and thereby to
address each of the problems this entailed, Ruscio, Ruscio, and
Meron (2007) introduced a technique to produce comparison
graphs using parallel analyses of artificial categorical and dimensional data. These artificial data reproduced important characteristics of the empirical data (e.g., sample size, number of variables,
If you're statistically inclined, CCFI just uses Root mean squared residuals to determine the "error" between the observed distribution and these two theoretical distributions.
"These two fit values are then combined into the CCFI:
CCFI RMSRd ⁄ (RMSRd RMSRc) (2)
CCFI values range from 0 (strongest support for dimensional structure, obtained when RMSRd 0 and RMSRc 0) to 1 (strongest
support for categorical structure, obtained when RMSRc 0 and
RMSRd 0). A value of .50 is ambiguous (obtained when
The actual binary here is what Scott mentioned about the difference between flu and height. A person with flu is infected with influenza virus. That's a binary hidden variable. If we can't measure it directly or don't know whether it exists, all of these statistical tests on (possibly) correlated attributes we do know exist and can measure are attempts to infer the presence of the actual hidden binary variable.
To some extent, it does just come down to whether this is a useful way of thinking, though. Presumably a lot of people have at least one active influence virus cell inside of whatever skin/world boundary we consider to be within their body, but only at some level of viral load sufficient to overwhelm immune response long enough to manifest symptoms do we consider that person to "have the flu."
Remembering Scott's classic categories are made for man, this only really matters to the extent it changes treatment plans. Knowing infectious diseases are caused by germs means we can treat them by performing some intervention that either kills the germs directly or aids the immune system itself in doing so. If we don't know the underlying cause or whether there even is one, we can only treat the symptoms.
I immediately noted that there seemed to be a discontinuity in the CCFI figure - while it is continuous over certain ranges, there seemed to be a jump in the middle. Is this just an artifact of what was represented? Or, is there some meaning behind it?
Psychological constructs in general are just low-dimensional approximations of complex, high-dimensional processes. The relevant question is not "are they real?", but "are they useful?".
For a similar discussion, see section "Realist intuitions impede progress in psychology" on page 4 here: https://psyarxiv.com/xj5uq
This is a conventional take which doesn't even attempt to grapple with the true complexities of the issue. The question is not whether current diagnoses are dimensional or categorical but rather whether they exist as meaningful separate diseases at all. And most data points suggest the answer is no, that the current system is a joke. A nosology useful to clinicians for efficient collegial
communicate but with no benefit - and often harm - to the patient.
Mentioning riches as an example of a dimensional variable is apt because it appears to be as useful a variable as depression in understanding human beings (I.e. not). That's because a) it's unreliable - most people's wealth fluctuates, often quite drastically, over the course of their lives. And of course b) it doesn't actually exist - money is a social construct.
When we talk about wealth what are we really attempting to get at? The variable that scientists - and particularly epidemiologists - have found most approximates that is socioeconomic status, which takes into account education, profession.and economic resources.
Depression more than likely is but one pillar of a larger, actually useful category - perhaps "internalizing disorder". Or a more accurate system might blow up the whole thing and not even use the heterogeneous DSM concept of depression at all.
Any system must deal seriously not only with the current in-vogue biological factors, but also must account for culture and time bound disorders and the drastically different rates of recovery of mental illnesses depending on where one is (i.e. westernized vs non westernized regions). When outcomes for schizophrenia are better in sub saharan africa than the US, something is wrong.
Perhaps depression is comparable to pain. 'Pain' is also not a valid diagnosis, but merely a symptom, even though you can treat that symptom with pain killers. A person who is in pain because his leg is broken, needs treatment for a broken leg, not merely treatment for pain, although pain treatment can be temporarily helpful.
Yet a person who is in pain due to cancer, isn't helped with a splint...
Some people may be depressed because their regulation system works poorly. Others may have shitty lives and see no prospect of changing that. These are as similar as a broken bone and cancer.
---
And I agree that context matters a lot too. In fact, disorders are often defined based on dysfunction, so societal inclusion and acceptance can be the difference between something being regarded as a disorder or not. If the government likes to torture people and a decent subset of society celebrates torturers as heroes, a pathological desire to torture can be fully acceptable, if it is channeled in the right way.
Your first point is apt. Much work in the sociology of mental disorder argues just that. Once the DSM in it's infinite wisdom decided to go etiologically agnostic it introduced this issue. In DSM 5 it does try to limit this: "An expectable or
culturally approved response to a common stressor or loss,
such as the death of a loved one, is not a mental disorder."
"Expected or culturally approved response" is a notable qualifier and seems to more reflect capitalism's need for an infinitely malleable population without inconveniently deep desires or attachments than an underlying reality. So, in other words, a form of intellectual tokenism to cultural/contextual factors.
On the second point, again DSM 5 attempts to avoid this, particularly in light of past disasters like the classification of homosexuality as a mental illness. It added the qualification that the syndrome must cause the individual distress, or in old school language be "ego-dystonic". Although there are exceptions to this, notably OCD and many of the personality disorders. Not to mention cases where individuals are committed to mental institutions against their will. So, contradictions abound, there is no unified framework or understanding, just a patchwork quilt marrying the economic interests of the "healers", the legitimation of suffering and moral absolution needs of the population, and the social control interests of those in power.
Don’t forget that someone can be in acute distress, but not agree (either fairly reasonably, as judged by a group of ten average bystanders) or unreasonably (because it will be easier for the aliens to find him there, so they can keep beaming mind control rays at them), that being in a psychiatric hospital offers a good possible solution to their distress.
Also, at least here in Canada, it’s extremely difficult to get someone committed to a psychiatric hospital. They basically have to be sitting in Emerg with a loaded gun in their lap, explaining clearly who they will kill before killing themselves, or one day away from a heart attack because they’ve starved themselves so badly. The involuntary commitment orders are also short and hard to renew.
And like all attempts to deal with complex problems using the legal system, there are big advantages to this, as well as big. disadvantages. It does, though, greatly reduce the use of such measures as a method of social control. Valium for miserable middle class housewives in the 50s was much more effective.
Isn't OCD an anxiety disorder and expressly ego dystonic? There's a separate, basically "Conscientiousness up to 11" condition they call obsessive-compulsive personality disorder, OCPD.
Weirdly, the latest DSM revisions put OCD (along with hoarding) into their own section, took them out of anxiety disorders. Doesn't make any sense to me, as while OCD clearly has some of its own brain weirdness going on, the commonality of using behaviour to avoid/try to reduce anxiety (while actually feeding it, sigh) is there. In the case of OCD and hoarding, the anxiety is around the obsessive thoughts, and the avoidance is avoidance of DOUBT (did I actually turn off the stove properly? might I need this one day?)
My understanding is that those with OCD symptoms are particularly likely as compared to, say, hoarding or agoraphobia to not have a problem with it. Even if the latter 2 don't seek treatment, upon being asked they will generally admit it's problematic. But there are case studies of ocd where individuals will design their entire lives around these rituals in highly disruptive and costly (time or otherwise) ways that any observer will consider batshit crazy, but they are fine with it. The case studies generally emerge from them being seen for something else, and this will come up.
Having said all of that, I don't have any particularly deep knowledge of ocd, so I may be missing something. Personality disorders are the more hallmark examples of ego-syntonic, so it may be safer to stick with that.
Either way it's a problematic area. Telling someone with every flu symptom they don't have the flu if they don't believe it and/or if they don't have a problem with puking all day is problematic, but so is the nonconsensual shoving of stigmatic labels by powerful "helpers" onto the deviant.
The APA wants desperately to maintain the appearance of neutrality by medicalizing everything, but the truth is there is no escaping the moral dimensions of human behavior. Such questions can only be avoided to our detriment.
I've been under the impression that there's two obsessive-compulsive disorders - OCD which is an ego-dystonic anxiety disorder characterized by intrusive thoughts, and Obsessive-Compulsive Personality Disorder, which is ego-syntonic and more like an orderly, conscientious personality driven beyond 11.
Yeah, one thing I wish was more discussed in the mental illness discussion is cultural context.
I have Seasonal Affective Disorder. I get sleepy and cranky and low energy in winter, and don't want to do anything. Like most with SAD, I am of Scandinavian descent. It seems likely to me that SAD is less a "disorder" in the traditional sense than it is a reasonable evolutionary defense against harsh northern winters: in ancient times, people who stayed near the fire probably did better than people who went out and played in the snow. SAD isn't something that's "wrong" with me, per se--it's a mismatch between a reasonable biological defense mechanism and the modern-day reality of having to work 9-to-5, even in winter.
This sort of mismatch, or having disorders that only occur in some cultures, or whose symptoms vary depending on culture, seems to point to a good deal of societal influence.
Very much so. There's evidence (beyond common sense) for this on multiple disorders.
Also, recent work suggests that disorders are exaggerations of natural temperaments. And a variety of temperaments is good for group survival. For example a study found that groups that contain neurotics are much more likely to survive than those without because the neurotic is always on the lookout for danger and notices it right away while more positive or laid back people would ignore or not even notice early signs of danger (i.e. smoke in the case of a fire).
But some temperaments are maladaptive to their current environment. ADHD is a prime example. This (1) is a great overview of the evo psych of hiw it used to be individually useful and this (2) recent study found that indeed adhd gene variants are declining in modern populations. One wonders what effect this will have on group survival.
Indeed. It seems pretty obvious to me that society is not set up to satisfy our physical and mental needs, which evolved around a very different way of life, but to maximize other things.
That doesn't mean that we should go back to a hunter-gatherer lifestyle, but I think that we have to recognize that fairly normal human behavior can be dysfunctional in today's society.
Of course, a good therapy for SAD is light therapy, which deceives us into thinking it is not winter.
This is helpful. I do think it strange however that you go from a nuanced complex model of causality to using an oversimplified variable on the other end. As you're aware, there's no such thing as depression. There's depression-anxiety, depression-addiction, depression-heart disease, depression-addiction-anxiety-heart disease - but alone it may as well be a big foot sighting
Why does that matter? Because it renders either false or at best misleading some of your conclusions. For example, you say that bipolar is dynamic but adhd is not. But adhd has a high rate of co-occurence with bipolar, cyclothymia and cyclothymic temperament. So are you only talking about the 2 times in history bipolar and adhd have appeared alone, or are they somehow both dynamic and not dynamic when they join forces?
I made an oopsie - it's borderline and cyclothymia, not bipolar. But the question stands as there is significant overlap in many of the listed conflicting conditions.
The taxon-dimension distinction seems important in discussions of talent; while talent varies greatly, "genius" as a truly separate category doesn't seem to exist. But many people, including Freddie there, conflate the question of whether genius is real with the question of whether talent is real.
The "as a truly separate category" caveat is important, there. I'll never be as athletic as Wilt Chamberlain, but that's true in the sense that I'll never be as rich as Jeff Bezos. Not in the sense that I'll never be as rabbit-y as a rabbit.
This has significant implications for how we should handle extreme talent. If you go digging through the links in the link I posted, you'll see various people fretting over the social implications of saying that some people are geniuses and other people are not. They're right to fret; it's healthier socially, as well as more accurate, to avoid drawing that dividing line.
"You are more talented than I am" is a better way to approach the brilliant than "you are a genius and I am not".
"By their fruits you shall know them". The outcomes achieved by some individuals is so far above others that it is silly to democratize it. Just because they are categorically different does not mean they are another species - that's a straw man.
And the minute one gives an inch in the process of thinking to frets about social implications is the minute one stops thinking with any clarity or honesty. To think is to exaggerate and to exaggerate is to polarize and to polarize has negative social implications.
But they're not so far above all others. For every incredible supergenius there are a bunch of people almost as good, and for each of those people there are a bunch of people almost as good, and so on till you reach unexceptional people.
As for the social implications, well, the facts are pretty clear so it's a good time to think about what those facts mean.
By the same reasoning, intellectual disability would not exist, although it is obvious that below a certain level of intellectual ability, you aren't really playing the same game anymore.
Some intellectual disabilities are clearly identifiable as particular things. Down's syndrome is also called trisomy 21 because it results from trisomy on the 21st chromosome. You either have that or you don't.
But yes, there are disabled people who occupy the same smooth curve as the people we call geniuses.
If our measure is IQ, then I think there will be people with acute conditions like Down's with the same score as people who are just on the low end of the bell curve without any distinct condition. Both people will be expected to have comparable academic performance, but I think those with Downs would be expected to have less ability to live independently.
Nope; the ability to live independently is not different for two people who have the same IQ, when one has Down’s and the other doesn’t. Lots of other factors at play (education and supports, demands of the surrounding society, whether there are also major physical health issues,,,)
My understanding was that Arthur Jensen found that what might be called "familial" cases of low IQ to be more capable (outside the classroom) than "organic" cases. I can't remember where I originally read that, but in this interview he says most people with IQs above 40 or 50 are "biologically normal" and just part of the bell curve's range. He also says that even with a very low IQ "showing generally good judgment in the ordinary affairs of life should rule out a diagnosis of mental retardation".
Veryvery low IQ, which we classify as intellectual disability (lowest 2% of pop, w/dig functional impairment) pretty much never occurs randomly or even by normal genetic variation.
There has to be an exceptional cause; genetic abnormalities like Down’s, fetal alcohol syndrome and other teratogens, severe neglect and isolation.... Even most people of very low IQ that’s in the ‘normal’ range have usually experienced something that actively pushes intellectual ability down. Long periods of very poor nutrition....
But the other end of the curve doesn’t seem to be about anything extraordinary besides luck; more a combo of lots of luck within normal genetic variation, lack of factors that could seriously impair that ability, and opportunity to both develop ability and to show it. Plus whatever cultural/historical moment that this person’s ability fits into well.
That lack of down-pushing factos resembles the income–happiness relation. Increased income does not make happy, it only removes causes for unhappiness. And (broadly!) around 60k/y the marginal happiness vanishes, and money shifts into a different value for life ("keeping score" in one's (aspired to?) peer group for example).
That sounds doubtful to me. If there are an enormous number of genes (plus random developmental factors) of small effect and they add up to produce a bell curve, then there will be some people at the very low end without any of those large effect factors (same with at the high end). The main reason for that not to be the case is if there are enough people with those large effect factors to fill up that 2%, and those factors are indeed so large that even getting a tails on every binomial coinflip wouldn't go down that far. My thinking had been informed by what I'd heard about people classified as retarded, with IQs at least two standard deviations below the median. In a normal distribution that would be about 2.5% of the population.
An argument I've encountered that ADHD "really is" a specific medical condition, and not just a fancy name for below-average concentration skills, is that apparently when you give ADHD medicine to a person without ADHD, it actually makes them more jittery and less able to focus -- IOW the medicine has opposite effects on people with and without ADHD. Is that true, and does the argument prove what it sets out to prove?
That would still work in a dimensional model. Like, imagine everyone has an "ADHDness" score from -10 to 10. And ADHD diagnoses are clustered in 0-10, but medication moves you 10 points in the other direction, and past -10 you get negative side effects. So someone at 5 takes medication and goes to -5, someone who starts at -7 goes to -17 which is outside the normal distribution and gives negative side effects.
This doesn't seem true. Aside from the popular trope of speed users being famously productive while high, which from my limited experience seems true, amphetamine use to get through finals week in very difficult or competitive college majors is definitely real. It may be making people more jittery, but it doesn't decrease ability to focus.
Nope, stimulants make everyone more focussed. That’s one of the reasons we love our coffee, tea and nicotine so much.
People with ADD/ADHD just need more stimulants to get the same effect (with huge differences in how much of what type how often, unrelated to symptom severity, weight, age etc). That supports the dimensional claim.
Oh, forgot the second part; anyone, ADHD or not, who takes too high a dose of stimulants will feel jittery, less focussed etc. Too high just has to be higher for people with attention problems.
This is a smart, entertaining post and I learned a lot. I was also reminded of something that I am reminded of a lot, which is that a lot of very smart people don’t really know much about addiction or at least don’t think enough about the power of words in its weird realm.
The exclamation point after “gambling addiction” I found particularly troubling, and a little snarky. Spend some time at a GA meeting and there will be no question in your mind that it’s an extremistanic not dimensional phenomenon. There is no meaningful line that connects my thrice a decade purchase of lottery tickets and gambling addiction.
My own experience and long-term observations of folks in recovery tell the same story about alcohol. There are cats and dogs and to an alcoholic alcohol is catnip, which lots of dogs might have now and again but does not lead them to massively destructive behavior. Also, sadly, while Jeff Bezos could buy enough (I suppose) ivory back scratchers to exit his personal extremistanic state, the addict has a one way ticket. Pickles cannot revert to cucumbers, etc.
Why do I bother to write this? Because, again in my experience, one of the defining features of addiction is that there is a constant internal dialogue that amounts to “abstinence is an overreaction, I can [gamble, drink, have the occasional benzo, etc.] just like everybody else.” It’s a disease that works to convince the afflicted that they are healthy. So in my view it is really dangerous to casually propagate dimensionality theories about addiction. Down that path lies an enormous chasm of pain for the addict and those around them.
I have no idea how you could analyze this mathematically without any ability to estimate parameters of the actual generating process, but there certainly is a formalism in recurrent dynamical systems whereby some diverge and some don't. The actual sensitivity to each parameter is real-valued and on a spectrum, but "diverges or not" is a strict binary nonetheless.
That seems to be what is happening with addiction. Whatever feedback loop causes behavior to either reinforce and become more extreme or rewards to deaden and repetition to get boring tends toward extremism to the extent that it spirals completely out of control in some people, while converging to some steady state short of that in others.
That is maybe missing in this kind of purely statistical analysis that dimensional traits can produce binary outcomes because "disease" is really a recurrence relation. It's a function not only of the traits we're measuring, but the state of your body at all previous points in time.
Consider professional gamblers. Consider people that participate in every available lottery. Is there ‘no meaningful line’ between their behaviour and that of addicts? You compare only your extreme to the extreme of addicts and conclude it has to be taxonomic. That’s just using anecdata as evidence.
I’m not sure what I did is meaningfully different from SA’s wealth analysis. Casual empiricism (dangerous!) to be sure. Overall point that addiction exhibits the extremistanic characteristic of modern wealth distribution stands I believe.
"And look what isn’t on here – schizophrenia, which is just a really obvious separate taxon. You know, the condition where sometimes between ages 18 and 25 for men and ages 25 to 35 or so for women, over the course of a few weeks, seemingly normal people start getting extreme hallucinations and eventually devolve into a state where they often can’t live a normal life or even speak meaningful sentences? The taxometricians are saying ah, whatever, it happens to all of us, they’re just the people who it happens to more than average?"
2) "Has the flu" in terms of medical treatment isn't categorical based on "is infected by influenza virus or not" - it's an assessment of the dimensional response to being infected/exposed, which may run the whole way from "shrugged it off without even a sniffle or headache" to "death". As a reminder, this dimensional nature of the response to covid is part of what is making it so hard to manage.
3) If your chart is showing 'gender' as being more likely dimensional than categorial, then I think your chart has serious data issues. I myself would use that as a 'sniff test'.
Overall, I agree that looking at the human condition as a spectrum in most cases is very useful, and that it's probably best to intervene only so much as necessary to, as you say, allow a person to go on with their life in a productive and pursing happiness manner. Whether this is best money, or medical (procedure/chemical) treatment, or coaching into personal growth...there are lots of tools.
Gender is interesting because while there are clearly binary(ish) underlying variables (does this person have a Y chromosome? Does this person have activated androgen receptors?), they’re not necessarily all that socially relevant. Like outside of “you intend to get pregnant with this person” you shouldn’t really care about the underlying variable(s).
Sort of along the lines of someone can be firmly in the “not flu” category (unambiguously negative PCR test), but their symptoms strongly indicate “should stay home from work” then there’s no real issue with allowing them to stay home.
In most cases where you have a reason to care, what you care about are the actual secondary sex characteristics, not the underlying cause. If you're hiring a server for Hooter's, you're not really concerned whether an applicant has two X chromosomes, just that an applicant has visible large breasts and a vaguely feminine upper body, regardless of how they were generated.
I'm not even sure you really care when reproducing. At best, sex is a proxy measure of reproductive capacity as well, since a person can be unable to participate in whatever their half of the process would have been for reasons other than "wrong sex."
> this has another implication: stimulants shouldn’t be thought of as magic bullets that “cure” “ADHD” by fixing the underlying cause, in the same way that Tamiflu cures the flu by blocking flu viruses. They should be thought of as things that affect the underlying stew of variables that cause ADHD in some helpful way.
I don't think this is right. Conceptually, we should be able to say that, among the many dimensions along which we can measure a person, some of them are, by virtue of extreme or unfortunately-combined values, causing ADHD in that person.
And some of them are being modified by the expression of ADHD -- instead of being causes, they are among its effects.
The point of medication is to relieve a problem, such as an inability to see things. You can do that by removing a cause of the problem, and leaving the uncaused effect to disappear naturally (we can call this approach "laser eye surgery"), or you can do it by removing the effect while not doing anything about the cause. (We can call that approach "glasses".)
I had the impression that stimulants are viewed more as altering a symptom of ADHD than as affecting its causes.
I'm curious as to how this might work when there are more than two relevant categories: for example, colds also produce flu-ish symptoms, and the presence of another lump in the middle would move it away from the bimodal setup. I may have to look into this.
Minor nitpick, but you should probably make better figures than the hand-drawn ones on your website, even if the axes are completely 'symbolic' and only serve to prove a qualitative point. It'd look more professional.
Funnily enough, I really liked the hand drawn graphs - especially the rabbit/human one. In terms of communicating the idea it was nigh on perfect (for me..)
Now do the same thing with traditional US denominations for race and you'll understand why it is seen rejected as a biological construct by the overwhelming majority of geneticists and population scientists.
Is it really rejected by the "overwhelming majority of geneticists"? My understanding is that they've never had any problem using the term with other species, but there are political issues with applying it to humans. It is the case that race is not a Platonic discrete category, and is (at most) a much fuzzier and less fundamental category than sex.
> or you’ll get disillusioned and radicalized and start saying all psychiatry is fake.
This is about where I am.
My own experience with trying to get diagnoses and treatment for depression and ADHD for myself and for my kids has been super-frustrating. I know two young men who were diagnosed early with ADHD who later went through a smorgasbord of different diagnoses; one ended up as bi-polar and the other as autistic. My sense is of psychiatrists looking at clouds and saying "methinks it is like a weasel".
Add in the fact that you have to pay $1000s to each cloud-watcher before they can identify the right weasel and the fact that the next cloud-watcher will almost certainly tell you that the previous one was full of shit and it's hard to have confidence in the industry as a whole.
I wonder if, perhaps, this is why so many of us are eager to sign up with Scott's practice. At least Scott is aware of the uncertainty in the field. I fear the unwarranted certainty that so many doctors speak with most of all.
Exactly. It seems to me that psychiatry would be better off if they dropped the pretense that they are capable of diagnosing and instead, adopt a more experimental mindset, like this:
- Based on the symptoms, I think that there is a 60% chance that the patient has X, 30% they have Y and 10% something else.
- Let's do a treatment for X.
- It didn't work, so now I think that there is a 60% chance of Y, 20% of X and 20% something else.
- Let's try a treatment for Y.
- That didn't work either, so let's update to 30% X, 30% Y and 40% something else.
- Let's try a less common treatment for X.
- Hey, that worked, so only now I diagnose the patient with X.
Come to Canada, where the health system doesn’t require a diagnosis for the MD/clinic/medication to get paid for, where docs rarely get sued, and few people treat MDs like gods and then expect them to act like gods, and you’ll find a lot of practitioners who work approximately like that.
A lot of people have already identified the seemingly arbitrary deciding line between "dimensional" and "taxon" but it seems to me like there is a little question-begging in the other direction too.
Scott lists the criteria for various conditions, but the very existence of both the conditions and the criteria is, itself, down to some questionable statistical shenanigans.
Before asking whether depression is a categorical thing or a dimensional thing, shouldn't we be asking whether depression is a thing at all? And is it categorically a different thing than ADHD or bipolar? Or did they all just arise from more multi-variate cloud-staring?
This is a good point, because while people’s experiences of these ‘disorders’ are quite different, there’s a lot of overlap, co-morbidity and a lot of treatments that work for multiple, supposedly different, disorders.
I may have to use the "Jeff Bezos of absent-mindedness" line at some point. But beyond that, this is a helpful way of looking at something I've been thinking about on my own account for a while. (Though it would have helped if I hadn't read it on the Lorien website earlier.)
I wonder to what extent these 'objective' categories are just artifacts.
For example, imagine that angriness is a normal distribution, but psychiatrists don't actually test how angry someone is, but they consistently ask the question whether the person beats their partner. People who do are diagnosed with IED, those who do not, aren't.
What if anger is just a normal-distribution, where most people express this in societally acceptable ways, like posting angry screeds on Twitter? What if beating your partner has high societal and relationship costs, which result in high threshold costs. In other words, there is little cost to beating your partner more if you have done so before, but a high cost if you never did it before. This would then tend to result in an artificial dichotomy, that reflects external conditions, rather than the person being diagnosed.
The IED diagnoses would then seem meaningful, because it correctly identifies a 'real category' of people who beat their partner a lot (one of two clear bumps on a graph), but in reality, this is in largely part due to strong disapproval of partner-beating by society and most partners.
If you were to measure anger by number of angry tweets, you might find something close to a normal distribution, so then IED would suddenly no longer seem like a real category.
IED has never seemed like a real category to most people who work in mental health. Except in rare situations of significant brain damage, where the person truly has little/no control.
My criteria is always; does this person ´lose it’ only on people who are smaller, weaker, more vulnerable, who have less power than them? Only in situations where their reputations/career prospects will not be harmed if the victim stays quiet? Or when intoxicated? Then it’s not IED. Which leaves very very few people with IED.
I've been interested in a related topic recently: suppose there's a condition that's truly taxonic, but we live in a world with diagnostic fads and Szaszian malingering. Would we be able to find which people have the real condition?
Think back to the 1990s when every other young girl with vaguely negative body image was tagged with an "anorexia" label. Might this cause anorexia to be seen as dimensional when it's actually taxonic?
I can sort of see why autism might be taxometric. My wife has autism. She's extremely high-functioning and I'm weird enough that an outsider wouldn't necessarily see a huge difference between us, but from the inside, there definitely is. There's basically a social processing module that she's missing. Stuff that to me is trivially obvious to the point that I have no clue how to explain it because everyone just gets it is completely baffling to her. She does a splendid job dealing with social situations despite this, but it's definitely a difference. Likewise with the sensory sensitivities, which I basically don't have.
(Of course, this is just one anecdote, and may not generalize.)
Beyond the distinction between categorical - continuous distribution, there is also a more fine grained scheme, to which you allude, in which the "continuous" category is split into two sub-types: those with long and those with short tails. Short tailed distributions (e.g. the normal or exponential distribution) have a well defined scale (the standard deviation for the normal distribution) which allows you to say whether an individual is average or exceptional, even though the distribution is continuous. Height is an example. For long tails, i.e. power laws, you don't have such a measuring stick - they are "scale free". For example, wealth is power-law distributed: for any 10 people of net worth $x, there is one person of net worth $10x - this makes it much harder to define "exceptional cases" than in the case of normally distributed attributes. Here's my question: which "continuous" psychiatric conditions are long, and which are short tailed?
One place that categorical thinking (about ADHD) has real-world consequences is in academic accommodations. If a doctor signs off that you that you pass the bar for ADHD, you get 50% extra time on all exams, no questions asked. If you're not quite at the bar, nothing. As a professor, I've responded to this arbitrariness by trying to make exams less time-sensitive, but not with perfect success.
If ADHD is dimensional and prescribing medication is a matter of risks and benefits, why do we only prescribe it either EVERY DAY or not at all? Some people would like to have it available to take once a week, for, say, their most tedious task. What are the very serious risks that outweigh that need, assuming they have no history of addiction or heart problems?
I tried to look up the negative effects of taking adderall but they all talk about it as if it's totally different for people who do and do not "have ADHD".
Lots of people take their stimulants as needed, including fiddling with the dosage and with whether/when to take another dose.
And lots of MDs know this and are fine with it. If you are prescribed 30 Vyvanse 50 mg, 30 20 mg, and 30 methylphenidate 10 mg per month (as my son is), your doc knows you’re using it prn. Even if the scrip and the bottle don’t say that.
Scott, I'm reading the brief primer, but not seeing addressed why they choose these methods over normal cluster analysis, which is typically what you'd do when trying to decide whether some category is "real" or not statistically. Is it just because they have low-dimensional data? That doesn't seem like a good reason, since that makes cluster analysis even more interpretable if you can actually plot the clusters. "Within group variance is less than between group variance" at least seems more principled and intuitive than "CFFI is greater than 0.5."
They do actually directly address, just not until the end of the long article. They don't address it in much depth, but rather refer you to other articles. I think this one (https://tpb.psy.ohio-state.edu/papers/beauchaine 2003.pdf) seemed to contain the best explanation, but I'm still not satisfied.
Effectively, the complaint is that use of a clustering algorithm will always yield clusters even along purely dimensional taxa, and there is no way of knowing exactly how many clusters to yield. The reason I'm not satisfied is that presents a good reason not to use cluster analysis to discover taxa, but that isn't what I was asking. I was wondering what reason they have not to use a form of cluster analysis as the test for whether a taxa is categorical or not. That is, don't use a clustering algorithm to automatically discover statistically valid categories, but given you already have categories and a way to construct a distance function over the space of measured symptoms, just test whether between group variance is greater than within group variance along that distance given those categories as groups.
Minor nitpick, Scott uses Taleb's terminology incorrectly. Bezos doesn't live in Extremistan. Wealth is in Extremistan, while height is in Mediocristan.
Mediocristan is where you find all the nice normal distributions which look like Bell Curves. Extremistan is where you find distributions with really long tails (power law type stuff).
As I said it's a minor nitpick, but you say "Jeff Bezos lives in Extremistan" Taleb's point is that we all live in Extremistan. And that this has changed recently. That Bezos is not separated from us by his great wealth, that he does not live in a country different from ours, but that we are separated from our ancestors. That, as you point out, this is why our instincts about wealth are so wrong, because we are built for a time when someone couldn't be 5 orders of magnitude wealthier than everyone else.
By saying Bezos lives in Extremistan you imply that we don't and that is Taleb's whole point, that we do, and we don't realize it.
Another good analogy with height is that, theoretically, there's nothing _wrong_ with a short man; but, practically, he's generally going to struggle in life in our current social milieu. In the same way, there may be nothing inherently wrong with someone who struggles concentrating (maybe they're just not interested in the subjects of the current social milieu), but they'll struggle "fitting in". This might be a more tempered way of looking at the often strange spiritual implications of psychology and psychiatry rather than going full Szasz.
Another version of this: Imagine a society where basketball was extremely important, so that your ability to perform well on the court between the ages of 5 and 18 was the most important thing in determining your future success. There's nothing wrong with being short, but on average, taller people will do much, much better than shorter people at basketball, even if there are plenty of tall people who are also not that great at basketball and some Muggsy Bogues-types who are incredible in spite of their lack of height.
Now, imagine that society develops a pill that will make you taller. For people who are very short, it makes life much easier, as it can bring them up to average height. Even a Muggsy Bogues, who can succeed without taking it, would still benefit from it. But at a certain point, you get diminishing returns. Someone who is 6'6" and bad at basketball will not benefit much from being 6'9"--the height isn't the issue.
So there will be guidelines, particularly if there are negative side effects to the pill, but there will also be exceptions. In that case, you may say "As a general rule, a man needs to be under 5'6" to get the pill." A doctor may decide it's not worth it for Muggsy, but it is worth it for someone who is 5'7" but really struggling with basketball. But you would never give it to someone who is 6'1". Knowing that height is a spectrum and that the line between "short" and "tall" is in some sense arbitrary doesn't mean that there isn't an actual, quantifiable problem that needs to be overcome, and that's what's important here.
Great extension, although the idea I'm exercised about is the negative stigma of all of these psychological "problems". Whereas with height, there is very little benefit (maybe for horse jockeys), whereas psychological "problems" may, in some cases, provide benefit such as creativity, artistry, etc. Beyond side effects of these pills, I think there should be some trepidation on the part of the doctor and potentially some agency on the part of the pill taker.
Do you imagine that pill takers have no agency? On what planet? And that most MDs experience no trepidation about this stuff?
People SEEK help with their psych problems because they cause distress/dysfunction. Not because someone put them in a box that says ‘disordered - to treat’.
Sorry, I should have written "and potentially more agency". Agency isn't an isolated thing: if someone is constantly told that they have a "problem", any agency they do have may be distorted. This of course gets into deep and complicated philosophical and cultural questions about defining problematic behavior, what makes people feel they have a problem, and when something really is a problem which is enough to risk negative effects of any psychological treatments (pharmacological or not).
The classic example, of course, is that the DSM used to categorize being gay as a disorder. The methodology they used to undo this change -- extreme public pressure -- isn't very re-assuring.
I just wish that these philosophical issues were more openly discussed and wrestled with.
I would add that the standard, one-size-fits-all, schooling model is neither a natural environment nor a necessary one (there are many alternative schools that allow for self-paced, competency based, or even self-directed education). Yet many children are "diagnosed" with various conditions because "behaving in school" is regarded as a necessary norm. I've run alternative schools for decades and it is routine for me to see students with various diagnoses, medications, and treatments transfer to a more personalized environment and do just fine without the "medications." Their parents had sought out the professional help because the child did not fit into standard schooling. Outside the standard schooling model they were able to learn (sometimes quite rapidly) without being pathologized. Psychiatry is de facto based on unexamined scolianormative premises.
There's a classical logic reason to deny that there is a difference between categorical traits and dimensional ones. Take ADHD for example. If it is dimensional, then there will be cases where you want to say of someone that they are not ADHD, but they are not not ADHD either. They sit in the vague borderlands, with some ADHD symptoms, but not the full suite, or they don't have them very severely. Well, according to the rule of double negation, "being not not ADHD" = "being ADHD". From the preceding reasoning, it follows that the person is both ADHD and not ADHD, which is a contradiction. Since this reasoning will work with all dimensional/non-taxonic traits ("rich", "tall", etc.), it follows that no trait is truly dimensional. They are all categorical/taxonic. Now, it may be a permanent limitation on human knowledge that we can never know the precise boundary between being ADHD and not being ADHD, but there must be such a boundary. If you think, hey, let's just give up classical logic and say there are propositions with truth-value gaps, that leads to problems too. One of these is how to fix the boundary between propositions with truth values and those without without just replicating the whole vagueness problem all over again. Plus it seems, as my Dad would say, like too much sugar for a nickel.
From what I gather the RDoc framework (https://pubmed.ncbi.nlm.nih.gov/26845519/) is an attempt to steer psychiatric/psychological research in the direction of more dimensionality and away from categorization. I would think the advent of digital phenotyping and behavior tracking afforded by apps/bands would enable greater granularity of behavior/symptoms in this regard
A problem here is that many of the drugs that psychiatrists prescribe are controlled substances, so you need clear guidelines to avoid prosecution. Of course there's an obvious solution - stop controlling substances - but in the actual world.
The end reminds me of a conversation I had with Thomas Szasz many years ago. I asked how mental illness could be only a metaphorical "illness" if people who are not functional become functional by taking psychiatric medications. He said, "Do you know anyone who can't function without cigarettes? Would you say they suffer from a nicotine deficiency?" A similarly pragmatic POV.
The level of ‘not functioning’ without cigarettes is far far less impairing and far shorter term than that of someone who cannot function without medics for a bipolar disorder or schizophrenia.
And nobody is saying (at least nowadays) that the meds for such serious mental illness are fulfilling some kind of deficiency.
So this argument is not a valid one now, if it ever was.
The point was not to advance Szasz's argument (which I believe was always part intentionally provocation) but to note the consonance of Szasz's comment with Scott's pragmatism in looking at whether the patient's life can be improved rather than trying to validate their inclusion in a category or to settle the question of the true etiology--biological or behavioral--of mental illness.
I don't think you are properly following out the logic of your argument. You start with flu because we have an unambiguous test, infection with the influenza organism, that shows it to be categorical, you either do have it or don't. If the various statistical tests show it instead to be a continuum, that's evidence not that it is a continuum but that they are insufficiently powerful to tell. That's a straightforward Bayesian argument, starting with a very strong prior, itself based on direct evidence, that people either do have flu or don't.
In the case of gender we again have a test, indeed two tests with almost perfect overlap, genetics and structure, that divides the population into two categories that cover almost everyone. If the statistical tests that were used fail to identify it as category rather than continuum, that's evidence not that it's a continuum but that the tests are sometimes insufficiently powerful to tell. It follows from that that the failure of the tests to identify schizophrenia as categorical doesn't mean it isn't categorical. Indeed, if you have other strong evidence that it is, it gives you another strong reason to lower your confidence that the tests give the right answer.
One could, I suppose, try to avoid that conclusion by saying that what they are measuring is gender, not sex, and it isn't defined by genetics or structure. That's like saying that what you are looking for is not infection with the influenza virus but symptoms of flu. But in both cases, that amounts to throwing away strong evidence — the existence of an unambiguous categorical difference that correlates with the symptoms being observed. How, after all, do you decide what the symptoms of male or female gender are, other than by observing their correlation with other symptoms of the same gender? So how can it make sense to throw out XX/XY genetics, which correlate pretty strongly with m/f gender?
There is a third possibility, that the test can't detect flu is categorical because the symptoms being measured are too weakly correlated with the presence of virus. That doesn't indicate a problem with the statistical test itself but with the data.
That is likely what is going on with gender, where they're measuring something like adherence to social norms that doesn't correlate as strongly with chromosomes as actual secondary sex characteristics and calling that gender, but honestly, who knows? It's a meta-analysis and every study could have been measuring something different.
Not sure if the figure style has a particular pedogogical purpose, but here are some less pixelated versions you are free to use, Scott (and I can fiddle with them further if they don't match the existing ones properly).
Ed Tufte (an absolute madman/madlad of figure design) once advised me to use Gill for figure text, and although I disagree with him on a lot, that's been my default ever since.
Hard to argue with Tufte! But the point of comic sans is to emulate hand-drawn letters, which is what I think would fit the style that Scott is going for with these charts. Namely, "this isn't real data, I'm just sketching this to make a point".
Interesting analysis. In order to make it more comprehensive, I'd add the concept of a threshold effect. We see these different types of systems, where reaching a certain threshold in a continuous variable system has a dramatically different effect than any value below that threshold.
The action potential in a neuron is a classic example, where a slightly lower intracellular voltage doesn't trigger the neuron to fire, but then once the threshold is reached a complex series of events unfolds. Another example is phosphorylation of the rb protein, which requires a certain threshold to be reached to trigger the cell cycle. Below-threshold rb phosphorylation gives you no cell division. Once the threshold is reached, the cell will divide.
The gender thing is cute, but what does it actually mean? Some people are saying that if the test doesn't show gender as taxonic then it's obviously bunk. That's certainly true if they've done the test properly, with at least one factor indicating biological sex. But what if they haven't (as seems to be the case)? Does that mean they're measuring some kind of "gender minus sex"? Should we expect that to be taxonic?
That is my assumption, that they have focused on the psychological side of gender. What I find interesting is if - assuming dimensionality of that trait - most people might be able to play roles of both genders and transsexuality means just male-bodied person with personality heavily skewed towards female (or vice versa). Or in other words: is transsexuality dimensional as well?
it's interesting to think about a difference between absolute and relative categories, sort of complicates the relationship between the dimensional and the categorical.
rabbits and humans are categorically distinct in relation to one another and according to specific criteria. but if you abstract either term from the relation, the categorical definition says virtually nothing about the thing it defines (ie. a certain weight or what have you).. its Diogenes with the chicken..
relative categories are pragmatic constructions which are highly unstable, misinterpretable because of their contingency, hence the aforementioned example. the problem is that, qua the terms of the definition, the relatively defined category can belong to a larger set of things that share the qualities by which it is defined (again, size, shape, weight, whatever) -- whence comes the possibility of some equivocal identification. the relative category can inadvertently create a new dimensionality consisting of the vague objects falling under it (especially if empirical conditions are not ideal).
an absolute category, by contrast, would need to be defined according to terms which do not and could not make something falling under it a member of some more-general set (of arbitrarily non-rabbitish things, or what have you).
and with an absolute or singular definition it need not be a matter of either/or in terms of diagnosis, or even both/and.. it's a matter of necessarily belonging to an absolute category to a contingent degree (which of course could still be 100%). so i suppose the absolute category diagnoses according to singular intensity rather than a bi- or multi-valent belonging in this or that category.
> My guess is most professionals, and an overwhelming majority of laymen, are actually confused on this point, and this messes them up in a lot of ways.
Thank you for writing this. This had annoyed me a lot, back in the school.
Many professors seemed to confuse the map with the territory, although they might have used confusing languages just for convenience' sake.
Regardless, such confusion have propagated to fellow students, and the vicious cycle continues.
Many physical diseases involving complex diagnostic criteria seemed to share similar proneness for confusion.
This kind of reasoning should be taught at med schools.
> I’ll grant them pedophilia – it really does seem like people either are or aren’t pedophiles and there’s something weird and specific going on there.
Total aside to your main point, but (speaking as one myself) I'm not sure if this is true. Certainly I know people with varying levels of attraction, people who are attracted to both children and adults but more to one or the other, people who only realized later in life that they are attracted to children, etc. I think this one could easily turn out to be dimensional.
In other notes, thank you for not conflating pedophiles with child molesters.
I think your comment about there being a lot of variation and the claim that pedophilia might be categorical are not necessarily inconsistent. The question here is: for some observable trait like level of attraction to children, does it looks like there is a bimodal distribution or a unimodal one? It could turn out to statistically look like two populations even if within each population there is lots of variation and even if the bell curves for the populations overlap somewhat (like the flu). And, on the other hand, it could look like one population with a long tail (like hypertension).
Ah, thank you. You're right that the distribution might be bimodal - maybe it's even most likely that it's bimodal - but I feel like we don't have enough information to know.
I've seen at least some evidence for more of a spectrum. I've talked to people with varying levels of attraction: some who could see kids as "cute" but were not motivated sexually, some who had attraction to kids but not as strong as to adults, all the way to those who (like me) are only attracted to kids. There are also plenty of adults who abuse kids but are not themselves pedophiles (according to measures of attraction from penile response to pictures of children). This is typically attributed to a crime of opportunity, or power dynamics, but I wonder if there isn't some attraction present, just at a lower level.
In other words, it wouldn't shock me if you get a big hump around normal adult attraction and then a tapering off, a la the graphs Scott had for hypertension or wealth. I don't know, but I think it's possible.
(All of this ignores, of course, the question of what we're even measuring. Strength of adult attraction? Child attraction? Adult attraction minus child attraction? Adult attraction divided by child attraction? etc.)
If "taxometrics" gives the wrong answer for schizophrenia and gender, shouldn't we just ignore it?
--
You suggest that for "dimensional" traits like wealth or ADHD-ness, we shouldn't expect a specific underlying cause. But extreme values of a dimensional trait seem like they might well have an underlying cause. If you ask why Jeff Bezos is so wealthy, the answer isn't, "well, you know, who can say, it's just a confluence of a bunch of small factors: he worked a bit harder than normal, his parents were a bit wealthier than normal, he saved a bit more scrupulously than most, etc., etc." No, there's one big reason, namely that he founded Amazon. Similarly, I think it's true that people at the true utter extremes of the height distribution have a single specific underlying disorder that causes them to be really really tall or short. It seems like an empirical question whether the extreme values of a dimensional trait have a specific underlying cause or not.
This seems right, but it also seems like when there are specific underlying causes (like founding a successful company), they should themselves be factors that are dimensional instead of categorical. Most people don't found any companies, so there's a big concentration at 0 companies founded, but then there are a good number of people with one small business that are just barely scraping by (think freelancers, ma and pa restaurants), and then a smaller number of people who founded a business with a handful of employees, or multiple small businesses, and then an even smaller number of people with... and then eventually you get to Bezos.
If, instead, founding a successful company was more like a binary distinction, you'd expect that to at least show up as at least a weak "step function" blip on the wealth distribution and make it look a bit less like a continuous.
Machine learning takes a bunch of items with labels ("rich", "not rich") and attributes ("owns more than 5 cars", "reads the New Yorker") and then comes up with a formula ("algorithm") for deciding whether an unknown item fits a label. The formula typically has no explanation (it might have a confidence value for a decision), but there are ways of giving a partial explanation of how it works (e.g., fitting a decision tree to the formula).
The DSM criteria sound like a simplified version of machine learning. And, as we know, machine learning used without care can have all kinds of problems; for example, built-in bias because wrong attributes were chosen or the attributes are correlated with other things that were ignored, such as gender or ethnicity.
Classification models like the ones you are talking about don't actually output a 0 or a 1 for a given input, they output a value in the range [0,1]. If you want to treat the model output as a binary classification, you have to set some arbitrary cut-off point, like 0.5.
Interesting but spoilt by muddle headed thinking about 'schizophrenia'. There is a vast literature stretching over thirty years, most of which has nothing to do with taxometrics, which supports the continuum model. Moreover, something that has been overlooked is that the diagnosis groups together a collection of symptoms which researchers have increasingly recognised may have nothing to do with each other, so its possible that some are taxonic (I have my suspicions about hallucinations) but some are not. I carried out a very large taxometric study of paranoid symptoms and the findings wholey supported a continuum model: Elahi, A., Perez Algorta, G., Varese, F., McIntyre, J. C., & Bentall, R. P. (2017). Do paranoid delusions exist on a continuum with subclinical paranoia? A multi-method taxometric study. Schizophrenia Research, 190, 77-81. doi:10.1016/j.schres.2017.03.022
My understanding, as a layman, is that the high correlation between the symptoms is why they're all put under the schizophrenia label (although Scott noted pervasive issues of that sort can undermine the idea of diagnosed mental diseases distinct from symptoms https://slatestarcodex.com/2016/12/14/ssc-journal-club-mental-disorders-as-networks/ ) and that GWAS studies support the idea that they all have a common cause.
Neither of these is correct. Factor analytic studies consistently yield a five factor solution for psychosis: positive symptoms, negative symptoms, depression, mania and cognitive disorganisation. The idea that 'schizophreia' is not one thing and that there are dimensions of psychopathology is pretty mainstream these days. As for genes, GWAS studies have not yielded any genes of major effect and it is now accepted that psychosis is highly polygenic (consistent with a continuum model) and that there is huge genetic overlap between different diagnoses.
Your first point is a solid response to my ignorance. The second is another story. I myself elsewhere in this thread brought up how I had though psychosis resembled certain forms of acute mental retardation and not a continuum like intelligence, and that Greg Cochran told me I was wrong because of GWAS. "Highly polygenic" doesn't undermine the notions of having a "common cause" any more than IQ being highly polygenic undermines the general intelligence factor. If different symptoms are correlated with different sets of genes (i.e five sets for the five factors), that would suggest separate causes.
Having worked with a lot of people with social anxiety and some with paranoid delusions and some with schizophrenia, I have to say; definitely a continuum for paranoia.
Let us not forget that even the most ‘’classic’ symptoms like hearing voices are not uncommon, usually at a less-distressing, less intrusive level, in many people when depressed or under a lot of stress.
But this is a symptom that is rarely asked about, when the person is high-functioning. Hell, if you’re white, middle to upper class, well-educated and not raving, you’ll probably be diagnosed as ‘depression with psychotic symptoms’ rather than schizophrenic, no matter what the progression and dominance of symptoms say. I ‘be seen it happen more than once, to the patient’s detriment.
I actually tried making that argument about schizophrenia to Greg Cochran, and he replied that GWAS studies really do support the notion that it's just the extreme end of broad variation, like mental retardation:
I really do like this piece in general. I am a physician and I also am an individual with high functioning ASD. My problem is with the final paragraph. Language and the meanings assigned to words is a highly variable thing, but as someone with ASD, my "feeling" is that terminology such as "a person with ASD" is much less binary/dualistic than "ASD person." Describing me as "a person with ASD" at least makes me feel like I am on a continuum that includes everybody else. Not that the way I as an individual feel about it is all that important. Just introducing a perspective.
Quite a few people who prefer "autistic person" to "person with autism" do so because they see their ASD as an essential part of their being. And that kind of essentialism troubles me, particularly in light of questions over whether ASD actually exists. Of course, the symptoms, in their immense variety, exists; the question is whether "ASD" is really a useful theoretical construct in explaining those symptoms. Lynn Waterhouse's 2013 book "Rethinking Autism: Variation and Complexity" argues that the answer is "No" – in her view, "autism" is a research dead-end, and we are only going to move forward if we abandon the concept – still research the symptoms and causes, but give up the idea that some unifying concept of "autism" is useful in understanding them. She and her coauthors argue that "The ASD diagnosis has blocked the discovery of valid biological variation in neurodevelopmental social impairment" – https://www.researchgate.net/publication/318463805_The_ASD_diagnosis_has_blocked_the_discovery_of_valid_biological_variation_in_neurodevelopmental_social_impairment – maybe one day the research community will listen to her and we'll actually wave the concept of ASD/autism goodbye, and replace it with a bunch of different concepts instead. What will people who have identified with the concept as part of their essence do when that finally happens? And I think, fear of political pushback from those people is part of why the research community is reluctant to listen to her (and other authors who say similar things).
I do understand your comments and largely agree with them. I can say with certainty that my "diagnosis" was both a blessing and a curse. It provided a very clear understanding for me (but especially for my spouse) of the things that were problematic for me for many years (I am now 52) while at the same time provided an unfortunate "veil" behind which to hide for a time. My self-aware struggle of working through those details over the last 7 years has been exceptionally valuable, and I have emerged from it with a greater sense of wholeness and an understanding of humanity in general, and so in that regard, I am thankful for the entire episode. I think it can absolutely be true that an ASD diagnosis is simply cornering someone (defining an absolute to someone or something that is simply on the the spectrum of normal or standard human characteristics) into a category of dysfunction when really they are simply at a different place of normality. I also agree that the political push-back can be exceptionally severe and often hinders the progress of good science. My point was simply in the way the actual language can be interpreted very differently by those with varying experiences. Thank you for the solid discussion.
It really feels like this linguistic distinction has very little to do with whether autism is a taxon or not and more to do with whether it is considered your defining characteristic or not. When you use the phrase, "person with autism", it's normally because the autism is relevant to the context. "Autistic person" or just "autistic" tends to be thrown around even when the autism is totally irrelevant.
Like, imagine that a newspaper is listing a set of people who had been killed in a natural disaster and that list reads, "...Scott Siskind, a well-known science blogger from Oakland; Steve Thomas, an AI-safety activist from Mountain View; Douglas Lewis, an autistic man from wherever-you-are-from..."
It doesn't really matter whether these classifications are taxonic. How active do you have to be before you are an activist? How many people need to know you before you are well-known? However, the way they are used infers that they are defining. That may be ok if it is that person themselves who wishes to be defined by their autism. It really isn't ok when it is somebody else doing the defining.
It's not really clear to me that what taxometrics is measuring is well-defined. We could of course *define* categorical properties to be ones that pass MAXCOV or some other test, but if we reduce categoricity to that, it's not clear why we should care about it. So what does it mean to "neatly, objectively separate into different groups"?
One answer would be "conceptually dividing things into these discrete categories is the right way to think about them". Spelled out like that it should be pretty clear that this can depend on a lot of things other than the statistical properties of the dataset, but I suspect that this interpretation is a big part of why taxometrics feel like they're telling us something important.
Another possibility would be "the process which generates the observed data significantly involves a discrete random variable". I see two problems with this one. First is that it's not really testable: we can get similar distributions by means of very different underlying processes. For example, if we have a variable X distributed according to a standard normal distribution, then arctan(100X) will be highly bimodal, and if our observables are three different noisy measures of arctan(100X), they'll pass the MAXCOV test, and I'm pretty sure that they or something very similar would pass any other statistical test of categoricity as well*, even though no discrete variables were involved in the process.
The other problem with characterizing categoricity as "the process which generates the observed data significantly involves a discrete random variable" is that the physical processes which actually produce the data are not the same sort of thing as the mathematical models we use to think about them. With a mathematically defined process for generating a random variable, we can say "look, right there, on line 3, there's a discrete random variable", but the physical process isn't always going to have some specific location of the variable that we could point to. If there's a specific gene or something, that's pretty clear-cut, but often there isn't. And when there isn't, whether or not there's a discrete variable involved is a property of the *model*, not the world, and we might get different answers depending on what model we use and how granular it is. For example, you talked about "having the flu" as a binary categorical property, and certainly under many situations it's appropriate to model it as a discrete random variable. But a more detailed model might look at viral count and antibody count as two real variables which change continuously over time. Or something like that; I know very little about immunology. But I'm pretty sure you can't tie it to something as physically unambiguous as "are there more than zero viruses in your body" because someone who fully recovered from the flu and has antibodies shouldn't be classified as infected if they inhale a few viruses.
Maybe these problems have been resolved somewhere in the taxometric literature, but I'm not seeing them addressed here or in the linked primer, and they seem pretty fundamental.
*because arctan(cX) converges in distribution to a coin flip between pi/2 and -pi/2 as c goes to infinity, so statistical tests shouldn't be able to distinguish it from the discrete case for large enough c
Time for the meta question! Is the distinction between taxonic and non-taxonic traits itself taxonic or non-taxonic? What would the CCFI distribution look like for lots of different traits?
There's a tasty and tempting irony in taxometrics. The field says: "Turns out many of these supposed disorders are actually traits that are non-taxonic." Then one is tempted to say "I'm going to care deeply about which traits end up in the binary bins of taxonic or non-taxonic!"
This kind of side-steps the really important question of "when and why do seemingly smooth distributions give rise to important and distinct taxa?"
The answer to this question is nearly always, "there are self-reinforcing effects going on and the taxa are divided by the point in the distribution where the variable will grow over time to where it will shrink".
So your income graph may look perfectly smooth, but there are nevertheless two distinct taxa in people who are living hand-to-mouth, who will see stagnating or declining incomes over time and people who are investing surplus income in future income generation, who will see income growing over time.
Similarly, disease infectiousness may be a continuous spectrum, but there is a big division at r = 1 between diseases that will die out after a few people have been sick and those that will become pandemic.
It feels like many (if not most) mental illnesses have this kind of flavor. The distinction between a person who is depressed and one who is merely miserable is not really how miserable they feel. The distinction is whether that misery compounds itself over time until they cannot get out of bed (and are then miserable about the fact they have not gotten out of bed) or whether it decays naturally as they switch to happier activities to make themselves feel better. Treatments, too, tend to focus on breaking cycles, not really shifting the set point.
It's ironic that this is missed in the article, because your example of the most clear taxon in Psychology is mostly defined by its instability. If your schizophrenics had been unable to speak meaningful sentences since childhood, would you be quite so convinced that they were not just at the long tail of the language development spectrum?
By this distinction, depression, addiction, anxiety, schizophrenia, bipolar disorder, etc. would likely be distinct taxa categorized by the point where they become unstable. ADHD and autism would probably be somewhat arbitrary lines drawn on a distribution.
In short, taxometrics doesn't seem well-validated as a statistical technique. Unlike most statistical techniques one sees in practice, it neither has backing from strong mathematical theory, nor from the "real-world stress test" of a large number of people independently using it on different problems. That doesn't mean it *couldn't* work, but feels like it has a closer family resemblance to "algorithms I personally invent for personal projects that seem to work OK" than "anything you might see used by eg Andrew Gelman in a paper."
Separately, I'm unsure it makes sense to apply it in psychiatric patient samples, even if the idea makes sense in some other contexts. From the post:
> After all that, you still have the data you have, which in psychiatric contexts will be sampled from the general population in a very non-uniform way.
> The idea makes sense in an idealized world where your research sample is drawn randomly from the population of All Possible Humans. But psychiatric samples are very unlike that. You can try to remedy that by introducing some control people from the general population, but then you’re introducing a two-category structure into the data (controls vs. patients)!
When I was in college I was depressed so I went to the doctor; they had me fill out a questionnaire and based on my answers decided I wasn't really depressed and basically told me to get over it. One of many experiences that really put me off seeking medical help :(
Could someone please do a meta-analysis of Comparison Curve Fit Index studies to determine if 'taxonicity' and 'dimensionality' are separate categories or just different points on a continuous spectrum?
First reaction; YES! So much what I’ve been thinking and teaching and explaining to patients for years.
Then so no no no; eating disorders and substance abuse as categorical? This mistake arises because psychiatrists (and most MDs and most hospital-based psychologists, the ones who do most of the research) only meet the most severe cases, the ones who haven’t managed to stop by themselves or with the help/push of concerned friends, families, employers, AA etc. (BTW, for those most severe cases, there’s very high co-morbidity with early trauma and/or personality disorders. Both also dimensional.)
I’m betting the researchers doing the studies that led to those results in the meta-analysis only included people severe enough to seek/ be brought to professional treatment. Plus we often don’t ask about these issues, unless it’s part of the presenting problem.
Scott, go find the research on how many people have ‘sub-clinical’ ED, alcohol abuse, etc. How many people are ‘overly careful’ about what they eat or how trim they stay, or who binge, but not to the point their teeth are rotting. How many have a year or two or three of drinking or drugging enough to start wreaking some havoc. How many manage to pull themselves back from the brink. To ‘fix themselves’, alone or with the help of a school counsellor, an EAP provider..... to start a virtuous cycle that leads them to a much better place. Without ever talking to their GP about it or seeing a psychiatrist.
"This mistake arises because psychiatrists (and most MDs and most hospital-based psychologists, the ones who do most of the research) only meet the most severe cases."
> I’ll grant them pedophilia – it really does seem like people either are or aren’t pedophiles and there’s something weird and specific going on there.
As a carrier of this trait, I'm conflicted about this myself.
On one hand, I'm definitely able to fall in love, have sex, and form emotional attachment with adults. I've had a reasonably full love life but none of my lovers ever were under the age of consent. Right now I am happily married with kids (and yes, my wife knows all about me).
On the other hand, I feel definitely binary about my sexual attractions. There are many adult females that are about as attractive to me as a crocodile. For an attraction to be possible, I need to see some hard-to-define childishness in demeanor that doesn't depend much on age but that most adult women (and even some children) totally lack.
So, if I define myself as someone sexually attracted to children (i.e. a binary category with a legal cutoff), then I am on a spectrum: I can experience attraction on both sides of the cutoff. But if I define myself as one attracted a certain personality/appearance trait, which is itself a spectrum, then I am binary: if you don't have this trait I have zero interest.
I believe when people talk about autism spectrum, they are talking about a different thing than taxonometrics. What they are saying is that there are multiple ways to be autistic, and all autistic vary a lot on their presentation of autism. They are trying to dispel the popular image of autism as Rain Man, or Sheldon Cooper. This is entirely compatible with autism being its own taxa, with some fuzzyness in the border, just like some people may have the flu, but no or few simptons, or not have the flu but have some flu-like simptons.
Anedoctly, I've seen activists saying, precisely this, that autism is a spectrum, but some people are clearly in the spectrum and some are clearly out.
It sort of seems like the psychiatric profession should move away from the notion of 'diagnosis'. Diagnosis is fundamentally a verb for categorizing. Perhaps it'd be more appropriate to think of things in terms of scores. Patients take a depression test, which gives them a 0-100% depression score, and then you can define ranges of that score that indicate the value of clinical intervention. Functionally that's sort of already what's happening, but re-framing it in this way seems like it might be a better epistemic map projection.
Reading this as a physician, I feel suddenly struck by how much of medicine may actually be comprised of things-more-like-height.
Hypertension, as mentioned, is a classic example, but I feel like actually the more closely you look at various health conditions, the less they independently exist as discrete things in the world.
A few examples;
Diabetes (type 2) - basically like high blood pressure. we use arbitrary cut-offs of certain Hba1c measures. The fact that ‘pre-diabetes’ is a diagnosis in itself is telling.
Dementia - very much a spectrum, we use scoring systems, ‘mild cognitive impairment’ being a diagnosis ‘before’ you reach a score “bad enough” to have dementia.
Heart attack - on a spectrum with stable and unstable angina. Yes we have various measures to determine how likely it is that part of the heart muscle is damaged (ECG changes, blood test markers, again arbitrary cut-offs) - but part of your heart muscle dying is not really something that does or doesn’t happen. Suppose 5 myocytes died because your heart was under strain temporarily? - not a heart attack.
Even infections - it’s not really as simple as ‘is this virus or bacteria present in X body system?’ - if you culture somebody’s nasal cavity, or poo, or skin, you will often grow bacteria, and these are not infections. One of the key defining criteria of a pneumonia is whether or not you can see an area of infection on a chest x-ray - again, this is obviously not yes or no.
I think extremely few things really exist in a discrete way (aside from genetic disorders controlled by a single gene, which seem to be an unusual case). We make up categories to describe continuous variables in a way which is most helpful for deciding when to use different treatments. Seems equally true to me for most mental and physical health conditions.
I feel like this missed a good opportunity to make another supporting point: Jeff Bezos only makes $81k/yr salary. (Everything else he has was likely fundraised by sales of AMZN stock to people looking to own small fractions of Amazon... probably 9-figures some years, but probably near 0 some other years. And it also would include a lot of people who are technically broke. Point being, categories are difficult, and easy to manipulate.)
Wonderful text, thanks a lot. There's even a new section in the DSM in which they want to make numbers out of all these complicated diagnoses, I think it's called "emerging theories and models". My colleagues like this a lot. Nice terminology for something that is probably mostly driven by convenience.
In the old days, there were complex psychiatric diagnoses, categorical, and the psychiatrist spent quite some time finding out the problem. The problem: you cannot run the nice parametric statistics, you need proper numbers.
So, rating scales were developed, Hamilton rating scale for depression, anxiety, and so on. The ratings were made by psychiatrists, and they needed to take classes to learn how to do it properly. The problem: it takes so much time. Imagine a randomized study with 200 participants, nobody has time to perform 200 interviews.
Then, more and more questionnaires were invented (the nice term for this is: "patient-reported outcomes"). Beck depression inventory, GAD-7 is also a questionnaire. When I ask my students in class, how do you want to measure X, they almost surely respond: "With a questionnaire". Using questionnaires, the researcher can save a lot of time because the patient is diagnosing himself or herself. More than 20 on BDI -> moderate depression (I don't remember the exact figure). No psychiatrist needed for this diagnosis. And since clinical studies are often collaborative, and every collaborater has a pet scale, many questionnaires were put on the table of the patient. The problem: piles of paper forms that no one wants to type into the computer.
Then, the internet came and everyone bought a smartphone. Nowadays, the patient receive a link to an ever-growing pile of online questionnaires, which you cannot escape until you have clicked on the last of, say, 500 questions. I have seen studies in which, according to my calculations, patients spent hours of with filling out online forms. One of the phd students involved in such projects told me that many patients just put a cross in the middle category because the online forms are way too long. There's also a nice orwellian word for this nightmare: "measurement-based care".
One more funny thing is that there are scientific guidelines from the regulatory authorities in medicine (EMA, FDA) that actually limit the use of all this. E.g., the need for a "primary outcome" in a clinical study, which prevents you from collecting 20 variables and choosing the one that shows most pretty results. E.g., the EMA guideline for patient-reported outcomes in oncology that says, at most 20 min for questionnaire. E.g., the EMA guideline for depression that tells the researchers to do blinded assessment using rating scales. I am digressing, sorry.
There is actually a quite sophisticated "representational theory of measurement" by Krantz, Suppes, Tversky, Luce. The theory was developed to enable measurement even in the absence of concatenation operations such as putting rods together so that the length adds up, or putting two objects in the same pane so that the weight is the sum of the two. In the social sciences, such concatenations don't exist, and Krantz et al.'s theory can be very helpful here to establish an interval scale. But the theory is complicated, so no one makes use of it, neither the proponents nor the opponents of the dimensional approach. Instead, the meaning of a scale is mostly established by its name. If the name of a scale is Novaco Anger Scale, it obviously measures anger. Add a few correlations with other "instruments", and claim that your scale is "valid".
One more funny thing: I think the whole measurement hype in psychology started with intelligence; and early intelligence test were made for diagnosing mental abilities in children. More recently (1980ies onwards), Falmagne and Doignon developed so-called knowledge structures for qualitative assessment of skills, so dancing plus singing is not equal to 2. This stuff is more and more used in e-learning systems like ALEKS that some of our children have to do homework with. In education, they noticed that one cannot make numbers out of everything.
Once I asked my psychotherapist about my diagnosis. His response: "Why would you want to know? I only use it for the health insurance."
I am fervently interested in whether or not you (and others here) have opinions on so-called "positive psychology". For the uninitiated, positive psych is a comparatively recent (1960s or so) effort to use science to understand mental wellness instead of mental illness. In the nutshell explanation I usually use, it's the difference between fixing a blown knee versus training to break the 4-minute mile.
Most of the pos psych stuff promoted (and I do mean promoted) to layman is suspiciously indistinguishable from self-help snake-oil (keep a gratitude journal! don't let failures get you down! develop a growth mindset!), with the caveat that it is, by and large, snake-oil that appears to have, on average, replicable results - per its own (questionable IMO) measures - when people buy into it.
A lot of it is sold (and I do mean sold) as preventative medicine, but I think it fits great with my 10-minutes-old understanding of this taxometric distinction. If most people are not so much afflicted by a mental disease as they are uncomfortable or disabled due to their position out on the tail vis-à-vis anxiety levels, it makes sense that sometimes mental health-oriented boosters /could/ help just as much as, or more than, mental disease-oriented corrections.
The evidence is chaotic soup served with statistical smoke-and-mirrors, but with my methodological background, I've blamed it mostly on early commitment to suboptimal (proxy) measures - not so much where you draw the line between tall/short, but whether or not the yardstick is remotely objective or validly measuring the phenomenon you say it is. Now I'm going to be turning over in my head also whether or not it's a case of: "My guess is most professionals, and an overwhelming majority of laymen, are actually confused on this point, and this messes them up in a lot of ways."
Homelessness is probably categorical enough that "person experiencing homelessness" may be more appropriate than "homeless person" if you care just about sending the right signal.
(Since it takes more bits to explain disagreement than to indicate agreement, and positive reinforcement is useful when true, please take my disagreement here to indicate that any portion I _haven't_ disagreed with is a portion that I agree with.)
You say that "I think a lot of people still want psychiatry to deliver the single [cause of a given psychiatric phenomenon]. It’s not going to be able to do that." I don't think the fact that a given phenomenon is dimensional means that this is impossible; I would read it as meaning that the root cause must also be dimensional. To massively oversimplify the brain, let's say that all other things being equal an increase of X% in the average activity of one's Anxiety Gland produces an X% increase in one's reported anxiety levels, and that all medications which affect anxiety are ultimately things that have an impact of reducing Anxiety Gland activity by some amount. (The stuff that can impact the activity levels of the Anxiety Gland may be complex and multivariate, but I don't think this is different from categorical issues - if there are developmental failsafes so that N out of M mostly independent processes have to fail in order to produce a Categorically Abnormal Anxiety Gland, otherwise the development of a Normal Anxiety Gland is an attractor state, I'd still call Categorical Abnormality of the Anxiety Gland the "single cause", especially if it was what could be affected by interventions.) This would still be a single cause; it would just be a single dimensional cause.
You also say that "If most mental disorders are dimensional variation rather than taxa, that kind of makes the DSM look pretty silly, doesn’t it?...All of this is predicated on the idea that [there are] specific thing[s] called [disorders] that you either do or don’t have." I think another way to regard the DSM, or at least what an idealized DSM could be, is a manual of best practices for tradeoffs which are codified as acceptable at arbitrary cutoffs, much like your hypothetical Sanders tax plan is an arbitrary cutoff made for practical purposes. If a patient has more than X% excess Quality, then the profession regards it as reasonable to experiment with certain interventions which fall under the banner of "Interventions for Excess Quality Disorder", but below that cutoff they think it's not worth the risk.
In this case, it would be good and necessary to renegotiate the definitions of Excess Quality Disorder as new information came up, even if "Excess Quality Disorder" is an arbitrary cutoff. Let's say that new research comes in indicating that Intervention A for mild Excess Quality Disorder is more harmful than previously expected; in that case we might move the boundaries of Excess Quality Disorder to reflect that we want to be more careful with it. Or maybe we discover that while our cutoff was X%, people with (0.8 * X)% excess Quality have a reduction in quality of life greater than we previously thought, so we move the boundaries in the other direction. In this case, "Excess Quality Disorder" is perhaps an inferior category to "Eligible for Intervention {A,B...Z}", but may be worth using for convenience, communication, or research.
Autism, like height and other dimensional traits are influenced by 100s or more genes, each with a small influence up or down. So traits that are influenced by relatively few genes a larger amount each should be more categorical, e.g. schizophrenia (if my impression of schizophrenia is correct).
One challenge I've personally experienced with definitions for psychiatric diagnoses that are based on multiple dimensions is that people tend to attribute all the (categorical) symptoms to people with only enough of them to fit the definition.
My experience is with autism, or at least autism-spectrum disorders. People are diagnosed with autism based on possessing characteristics such as problems with social interaction and communication, and repetitive behaviour or restricted interests (think: Rain Man). My son was diagnosed as "on the spectrum" at a young age. This meant that teachers and other professionals would assume he had all the most common characteristics, whereas in fact he had only a few, and this meant their approach was often not appropriate at all.
This happens all over the place, of course: it's the problem of "natural kinds". All instances of Democrats, ice creams, and churches are not alike in their categories on all dimensions. Politics is often a difficult thing not least because it forces hard demarcations where in reality they're fuzzy (I vote for party X because it's X or Y, not because I believe everything that X profess to believe).
We cannot carve the world at its joints, because they're in our mind rather than in the world. The same is, perhaps unsurprisingly, true of the mind itself.
Thanks for the fine exegesis. I have practiced psychiatry for many a year. DSM III came out when I was in medical school. It sought to make psychiatric diagnosis, which was vague and overly influence by psychoanalytic theory, more objective, but using description and taking away theory. It was felt essential to make psychiatry a legitimately medical specialty, and at the time it was hailed as a triumph. Alas, they threw out the baby with the bathwater. All of the useful tools of personal history, development, personality and temperament were junked. But whatever has been gained from categories makes it harder to treat patients as individuals. (Just ask the insurance company flunkies who rule over the prior authorization domain, and decide how many sessions and which medications are "medically necessary.") DSM IV and V made matters even worse. Not only are the debates about where the cutoffs are for a disorder inane, political considerations have tainted and even overwhelmed whatever medical legitimacy the descriptive categories might have had.
I have long been reconciled that my profession will never be as objective as brain surgery or cardiology. No matter how you dress it up, psychiatry is as much art as science, and I like it that way. As much I look forward to advances of neuroscience and pharmacology, the DSM ain't science, and Big Data tells a lot of Big Fibs.
I appreciated the argument on person-centred language. I've not seen this argument brought up in this way vs "recovery oriented" language. From a medical model it probably makes more sense, particularly when charting, to not use person-centered language.
I’m surprised to hear that narcissistic personality disorder is generally considered by psychiatrists to be categorical rather than dimensional. I’d love to learn more here.
It intuitively seems like people vary on a spectrum in terms of how selfish, egotistical, etc. they are. A lot of people certainly seem to have subclinical levels of narcissism.
Is it that narcissistic personality disorder is something radically different from the personality trait normally referred to as narcissism?
I liked the mention of extremistan. It made me wonder—
*Are* the distributions of psychological variables (e.g. anxiety) fat-tailed (e.g. power law distributed instead of bell curves)? If so, that would maybe be relevant to whether and why people underestimate how anxious GAD people can be, etc.
This is really interesting, but as someone who has ADHD, the idea that ADHD specifically is dimensional seems to directly contradict my experiences. The "symptoms" that get ADHD noticed and diagnosed tend to look like just having an unusual amount of trouble paying attention, the way Jeff Bezos has an unusual amount of money, but there's a slew of other things that have no reason to correlate with ADHD the way they do unless we consider them side effects of an underlying categorical difference.
If I just have an unusual amount of trouble concentrating, why does Adderall make me sleepy? Why does fidgeting help me think? Why are boredom and the perception of failure almost physically painful, in ways that confuses my non-ADHD friends when I describe them? Why do I share these traits with my roommate, who doesn't have difficulty concentrating at all, but has enough symptoms of hyperactive-type ADHD to also get a diagnosis? Why is there enough of a correlation between hyperactivity and inattention that the combined type is even recognized?
There's no reason inattention would correlate with these other traits without an underlying cause. A non-ADHD person who had a short attention span probably wouldn't also fall asleep after three cups of coffee or cry because they got mildly criticized at work.
I suspect some of the confounding findings have to do with the selection of variables that are included in the analysis and how they distribute through the general population in realms unrelated to the ‘condition’ being investigated. I don’t have the time to think through the implications, but further study of the efficacy of the statistical method for separating behavioral disorders is definitely warranted.
Having thought about this statistical method some more I wonder whether it could be used as a tool to improve our ability to diagnose different conditions. For example, if you add or drop certain diagnostic criteria, do you raise or lower the category score. If the criterium lowers the score, perhaps it shouldn’t be included in the diagnostic criteria.
tl;dr: A secret variable does exist, but you can't read it. [we might be in the future, though]
You can't avoid false negatives, but in many cases, you can definitely be certain that you don't have a false positive.
[according to Dr. Russel Barkley, who is a famous ADHD researcher]
That is not quite right. There actually is such a variable and it can be 1.
ADHD is brain damage in five specific affected brain regions, that predictably results in a 30% delay of executive functions for your age. In 2/3rds of the cases, this is genetically determined.
And there are also acquired cases, where it's known that strep-bacteria causes an autoimmune overreaction that causes that brain damage.
And yes, ADHD is highly comorbid with other things. And yes, SCT might be another attention disorder, that's separate from it, is not as treatable (yet) and less well understood.
[and having SCT implies 50% chance of having ADHD as well]
And yes, other kinds of brain damage also can lead you to present with ADHD symptoms.
And all of the above is not universally known or accepted in psychiatric practice.
But ADHD is actually a taxon.
The variable exists and you might not be able to reliably say that someone is a 0.
[unless you find some other disease or environmental cause...... like a kid playing Fortnite all day in school, which is an epidemic in its own right]
After all, the space between the variable=1 population bump and the majority of the bell to its left is not empty.
BUT...... you can and should be quite certain sometimes, that you do have "the real deal" in front of you, by looking at the parents or grandparents and seeing them have it as well.
Also seeing the "paradoxical stimulant effect" (stimulants usually don't make you calmer) would provides evidence for a "1", as well.
source:
excellent playlist "30 essential ideas you should know about ADHD" by Dr. Barkley on recent research into ADHD:
I agree with the observations you cite, but not with your conclusions. "The space between 0 and 1 is not empty, but at 1 you can be certain to have the real deal" (hope I paraphrased correctly) could be said about any psychiatric condition, even if their neural substrates might look less specific than what we know about ADHD so far. You could actually say that about intelligence ("If someone shows to be very smart, had smart parents and a brain that's different so-and-so, you can be certain to have the real deal").
Ah, been a year since I wrote that. Had to figure out, what I was on about myself first.
And then reread the post to remember what Scott was on about, so I hope I'm doing myself justice :)
So "being smart" is not a taxon, since IQ is dimensional.
If there was a gene that always puts you in the 120 to 140 range, no matter what, then that would be a gene that makes you smart. It would be a "fundamental hidden generator" for being 120-140 smart and a Taxon in its own right. But the 120 to 140 range itself would not be a taxon.
There probably are neurological substrate differences for IQ, but they great many "fundamental hidden generators".
ADHD meaning the thing that causes the statistically-visible (but not individually detectable!) brain-differences also has a "fundamental hidden generator".
But there are other things that can often/sometimes look like ADHD, but are something else. SCT or depression (though the latter would be a botched diagnosis probably, but diagnosing stuff is still hard).
So if you see a kid with ADHD symptoms, but no parents have it and they don't react paradoxically to stimulants? Maybe it's still ADHD. But keep more of an open mind, if something else might fit better. And if you find SCT, you can quickly accept that as a sole cause and possibly dismiss ADHD.
If they do have relatives who fit the ADHD type and they do react paradoxically to stimulants? Well, then you have enough evidence to be quite confident that they indeed have ADHD. Sure, you can look for other stuff too. But even if you find SCT, you'd assume first that it's a comorbidity instead of being the sole cause for the pathological behaviour. And keep treating the ADHD.
Even though ADHD is a taxon (has a "fundamental hidden generator", cause brain averages being the cause act as one), we don't really know whether this is the case for SCT.
In the end, the recommended drug regime is not too different between the two.
So I think, the psychiatrist would have to be extremely detail-oriented and knowledgeable to notice this. I don't think Scott does.
And it's also possible, that this distinction is proven enough yet, that it should be standard practice. (and partly that's politics)
It might not even matter, because you pretty much cycle thru the same drugs and stop when you find something that works. It matters only with which drugs you'd want to try first, AFAIR.
Hey, sorry, hadn't looked at the date and for some reason your comment showed up at the top for me, but thanks for replying anyway!
IQ is dimensional. What prevents us from conceiving ADHD as dimensional, as an "ADHDness"? It seems to be that attention deficits come on a wide spectrum of severity and, as you mentioned, can have different causes. I am highly doubtful that we have the diagnostic instruments necessary to reliably differentiate all these conditions, which of course doesn't disprove that there might be a "fundamental hidden generator" for what we call ADHD, but which makes it difficult to find said generator.
What I'm effectively saying is, not just is Scott not extremely detail-oriented and knowledgeable to notice this, nobody is, because the necessary knowledge doesn't exist.
If it finally does exist, I see two ways this could end up in our psychiatry books:
1.) Either we identify distinct subtypes of brain disorders that each get their own names, perhaps under an umbrella term like "disorders with attention deficits", similar what you are already doing with "ADHD" and "SCT", though I don't think a single one of those subtypes should be called ADHD, because they'd all share some elements of what we now call ADHD, or
2.) We understand it as something like "ADHDness" and treat it like a dimensional construct like intelligence.
Whether we lean towards 1) or 2) would not just depend on the evidence, but also an what kind of granularity we want / is helpful for helping people. (Heck, on the same basis we might even identify "Taxons" of intelligence if we janked up our granularity / resolution ABSURDLY high)
In the end I agree with you that, as things stand right now, we have to rely on trial and error anyway.
It's been a while since I viewed this. And I do not know what the current state of research is. When I wrote this a year ago, I might have been able to argue this confidently. And would have cared, because this ADHD-info and the taxon-definition was pretty fresh for me then.
Now I don't really wanna.
Irrelevant for me personally, whether it's a taxon or not.
Concern about the height example: what if there is a height gene H which can be 0/1. Suppose both H=0 and H=1 lead to unimodal (Gaussian?) phenotype height distributions. If you have a mixture model of this reality then the overall population's height distribution could be unimodal (Gaussian) as well? How can you distinguish this reality from the reality where gene H doesn't exist?
Some of this terminology seems useful for talking about consciousness (which I suppose is a sort of psychiatric condition); there’s obviously a useful distinction between humans and algae, but trying to pin down an exact dividing line proves difficult, especially when you entertain thought experiments like removing one neuron at a time from a brain. Lots of debates about e.g. animal consciousness seem possible to phrase in terms of the shape of this graph. See also the Sorites Paradox.
Sorites Paradox
1,000,000 grains is a heap.
If 1,000,000 grains is a heap then 999,999 grains is a heap.
So 999,999 grains is a heap.
If 999,999 grains is a heap then 999,998 grains is a heap.
So 999,998 grains is a heap.
If ...
... So 1 grain is a heap.
My take on that has always been that while categories such as "heap" are not *necessarily* defined with objective cutoff points, if it makes sense to define it anywhere, it'd be the point where the grains/articles of object are stacked in a pyramidal or conical configuration. So the fewest possible grains of sand that could constitute a "heap" would be four- three arranged in a triangle and one on top. In practice, unless you arrange them very carefully, with tweezers or such, four grains are unlikely to constitute a heap, because if you're pouring them onto a surface, you should expect it to take a lot more than four grains before any of them achieve a configuration more than one layer deep.
How many layers does your pyramidal configuration need to count as a heap?
I feel like this misses the point. The common parlance of 'heap' does not include any definitions about pyramidal configurations or anything else. I believe the truest definition of "heap" is anything that pattern-matches to a heap for most people.
Sorite's paradox is pointing out that there's no 'correct' cutoff for these categories along a spectrum. Which is exactly what Scott was pointing out.
> The common parlance of 'heap' does not include any definitions about pyramidal configurations or anything else.
Probably not pyramids per se... however it is not unreasonable to expect a 'heap' to involve things heaped on top of each other, which do look like that in minimal form. As suggested in their bottom line, the point is that a single layer is certainly not a heap.
But you're also right, the point is a reference to a paradox about a Greek word, and it has no obligation to work anything like the English word 'heap' we translate it with; if that's a property of 'σωρός' that's lost in translation we can still understand the idea being represented.
Two grains can be a heap if one grain is laid with its pointy side on top of the broad side of the other grain.
(If you squish them together a bit, two grains can even be a stack!)
Does anyone ever have to distinguish between a heap and a non-heap?
No, but they may have to distinguish between diagnosing someone with hypertension and not diagnosing someone with hypertension. :)
Category boundaries exist but are fuzzy. No, there's no fixed number of grains we'll all agree on as a cutoff for using the word, "heap," but you could probably define a numerical metric of "heapness" and we'd mostly agree on its shape. There would be a minimum of 0 heapness at 0 grains, and maybe another 0 heapness at "enough grains to form a black hole, or at least enough to become spherical under its own gravity." There would be a maximum, determined by combining many people's judgments, maybe somewhere near human height.
This also applies to many "alignment charts" or discussions of "what is a sandwich, really?"
I think this arises when you take a dimension and apply it to a category. Heaps of sand isn't really an issue as you don't treat a heap of sand any different from one grain less than a heap of sand, but in medicine there are dimension disorders with categorical treatment options, like gets the drugs/diagnosis or not, gets hospitalised/outpatient/nothing re treatment. I really annoys me when this is done for no reason, like with tax and govt transfers. There is no reason you need the bands since computers were invented we don't need the simplification of the math, you could just have a formula where the tax you pays go up faster percentage wise than your total income does. It could asymptote or have an s shape or whatever, it would need highscholl maths only, but with the bands people keep getting welfare cliffs and getting worked up when there income pops into a new band or the bands shift.
Linguist's perspective here.
The simplest way to define the semantics of "heap" is to treat it as some function mapping entities in the world to (True, False): some things are heaps and some things aren't (you could add a third category called "Underspecified" or something, but this doesn't help much because you run into the same pardox at the boundary between True and Underspecified).
Given this background, there are a few approaches to "solving" the paradox:
1) Allow for uncertainty: even if "X is a heap" is treated as being something that "is" True or False for each pile of grains, language users who are asked "is it a heap?" will, as Bayesians, have different degrees of confidence that the answer is "yes", from 0% (definitely not a heap) to 100% (definitely a heap). It is maintained that objects are either heaps or not heaps, but knowledge of which category they fall into can only be known approximately. In this formulation, an observer could rationally be 80% confident that a particular pile of grains is a heap--perhaps even once they have all relevant information available to them.
2) Reject that "heap" is function that maps entities to (True, False), and treat it as a function that maps from entities to the range [0:1], just as you might for scalar adjectives like "full" or "dark". Piles of grains range from being 0% heapish to 100% heapish. In this formulation, an observer might be 100% confident that a particular pile of grains is 80% heapish.
3) Both of the above at the same time. Heapishness is scalar as in (2) AND knowledge about heapishness of a particular pile is only ever approximate. In this formulation, an observer might be 80% sure that a particular pile is at least 90% heapish, and simultaneously 90% sure that a particular pile is at least 80% heapish.
4) Define meaning entirely in terms of usage, instead of the other way around: "is a heap" is literally the same thing as "speakers tend to declare that it is a heap when talking about it (assuming cooperative, sane, competent speech)." It is meaningless to decide whether things " really are" heaps: instead, we only ever decide--a real-world practical decision--whether in a particular moment we would like to declare (to ourselves or others, and possibly in the context of a philosophical debate) that something is a heap, or to declare that it is not a heap, or to not make any statement at all as to its heaphood (which is by far the most common decision). Our choice of behavior (and thus whether or not it "is" a "heap") will be determined in some complex way by the number of grains along with many other contextual and psychosocial factors. In this formulation, if across history nobody ever spoken or thought about whether a particular pile is a heap or not, the question of whether it is a heap or not is literally meaningless.
For all of these, the relationship between number of grains of sand and heapishness, or certainty of heaphood, or likelihood of someone calling it a "heap", is probably something like a sigmoid function or "s-curve". You could if you wanted to find the number of grains where the y value is exactly 50%, but there's nothing particularly interesting about that number of grains, and the exact number will be affected by other factors like the color of the sand, who the observer is, how much coffee they had that day, and so on.
Personally I find (4) the most interesting, as it implies that the "meanings" of words are not dictionary-like definitions, but are real physical processes extended in space and time, encompassing the grains of sand themselves, light, our sensory organs and nervous systems, our cognition and memory, children's learning of language, and our moment-to-moment motivations for wanting to use language at all. Whether or not something will (or "should") be called a "heap" becomes the same sort of question as whether or not you will (or "should") put ketchup on your burrito, or drive to Seattle, or commit suicide--and just as complicated to answer.
With consciousness in particular, an obvious-to-me conclusion is that some people are more conscious than others. Since that *sounds* so bad, you might also say that the same person can be more or less conscious at different times (excluding the obvious: sleep).
Consciousness could very well be categorical. What if we define it, for example, as "are you thinking about yourself?." Then, you either are or are not conscious at any particular point in time.
If that's your definition, there are definitely some people out there who are waaaay too conscious for my taste.
Very minor nitpick: hypertension guidelines have changed, and AHA defines stage 1 hypertension as SBP ≥130‐139 mm Hg or DBP ≥80‐89 mm Hg
Thanks, fixed.
(I think my father has some sort of strong opinion that this change was wrong and might have written an article about it somewhere, but I shouldn't be giving false information just out of family loyalty)
Oh, it's very arbitrary and probably will just result in more people using antihypertensives without increasing survival rates, but I guess the AHA sees value in scaring more people to take care of their cardiovascular health. European guidelines still use the 140 SBP cutoff
I suspect that the Number-Needed-to-Harm drops significantly with these aggressive hypertension definitions, especially as I see them being adhered to in cohorts where judgement should *definitely* be on person-centred basis i.e elderly care (without knowing the exact prevalence, my priors lean towards more elderly die from orthostatic syncopes and subsequent neck of femur fractures due to aggressive antihypertensive treatment than die from a SBP of 140-150...)
Scott would it be oversimplifying to say mental illness is on a spectrum and diagnoses are at best a way to communicate the cluster of symptoms?
I would say that diagnoses are on a spectrum too.
That was Freud's radical insight long ago, which the DSM initially rejected but is now slowly backing away from.
The problem is that the arbitrary cut off brushes under the table the suffering and impairment of those with subclinical manifestations - which is often similar to that over the threshold (1).
Once you admit dimensions, retaining simple categories is problematic. Particularly if one takes into account the absurd levels of mental illness co-occurence. If most with the flu also have a cold (removing the virus from the equation) - and a few with the flu have mad cows disease or strep throat or something else - and no one "in the wild" has just the flu - is the flu a separate meaningful disease?
After a while everything begins to blur and you're left with something like a p factor or some version of "problems of living". Which is likely for the best. We live in a world deeply hostile to any biologically sane way of life. Until we deal with that, we're just hacking at a never-ending stream of branches.
(1) https://www.sciencedirect.com/science/article/abs/pii/S0165178118305171
This was such a well-written article. I wish all doctors were this good at math. It would really help them make better decisions for their patients.
Does this article really signal proficiency in math? It mostly seems like it's arguing for a more useful way to think about categories vs spectrums. The most "mathy" parts are the statistical tests but Scott doesn't really explain how they work or what exactly they are measuring.
Understanding that sometimes numbers represent a measure of discrete categories and sometimes they represent a point on a spectrum is an important part of moving past a layman's concept of math, and seeing as MDs generally do a bare minimum of math (its nurses who transform a dose into an actual injection or rate) IMO this is raising the bar.
It's interesting that the most abstract form of math is category theory and category theory is, well, all categorical. Something either is or isn't an object of a category and two objects either are or are not linked by an arrow. Category theory subsumes all of math. Bartosz Milewski in his youtube course asks the question whether this reveals something ontological about the universe, or whether this merely reveals something about the way our brain work (he things it's the latter). If we are constrained by the structure of the brain to think categorically, rather than dimensionally, this sure does reveal why the human race is so plagued with tribalism.
Hey, aspiring category theorist and amateur mathematician here. I know this is entirely tangential to the discussion, but I don't agree with you on this. Certainly the definitions of what makes something "a category" are categorical (in the sense of the word used elsewhere in this thread), but that's true of literally every definition in math. If you don't specify exactly what your terms mean, then you can't expect other mathematicians to understand them in the same sense you do, and you can't write any formal proofs using those terms.
Tangentially, I'd also argue that category theory as it is practiced is not nearly as "categorical" as you are making it out to be; nobody ever asks questions like "is such-and-such an object in C?", and rarely do they ask questions like "is there an arrow X -> Y in C?" or even "is C a category?" -- they're much less interesting than questions like:
- "what properties does the category C have?" (e.g. does it have finite limits, finite colimits, infinite limits/colimits, a monoidal structure, a cartesian closed structure, is it a topos?)
- "what do these properties tell us about the internal structure of C?" (e.g. if C is cartesian closed, we can think of C as a C-enriched category)
- "can we infer properties of C from how C is related to other categories?" (e.g. adjoint functors preserving limits/colimits, adjoint functor theorems)
- "if we know what C is like, what does that tell us about other categories built out of C?" (e.g. slice category of a topos is a topos)
etc. I don't really know how to classify these kinds of results on a categorical/dimensional axis, they feel more like "building up a picture of what the field looks like" than "deciding whether something does or does not fit into Bucket X".
I'll leave the questions about the structure of the human brain or why humans are plagued with tribalism to someone who is more of an expert on those matters.
(I'm a long time reader of SSC, this is my first time posting! Apologies if this post is deemed unnecessary; but I hope it is both truthful and kind.)
I would call it mathematical (or statistical) literacy more than proficiency. Tragically even basic literacy is vanishingly rare.
My (non medical) PhD program long ago seems in retrospect to have been 3-4 years of dissecting peer-reviewed! articles in important! journals to diagnose where the authors violated assumptions, waved their hands, misrepresented their own data, and cherry-picked findings.
I work professionally in empirical studies now, and struggle constantly with colleagues and decision-makers who read the abstract (or only the title) and think so-and-so has been proven beyond dispute. (See also: problems with "systematic reviews" and "meta-analyses".) It is a huge problem with respect to policy & societal health/wellbeing (cf. the 'rona).
I don't think the article shows advanced Maths skills on Scott's part, but it does (as well as being extremely well written) show Scott's ability to communicate conceptual ideas - including mathamatical ones - with clarity and wit.
Scott himself has claimed numerous times he is bad at math. Of course bad by his standard is still above average, and more indicating that his math SAT section was below 600. He just worked his ass off to be statistically literate enough to understand scientific studies, even if he can't do any complicated math. This shows that nearly any doctor that took the time and effort to learn statistics, could understand this. There is just no incentive for an average doctor to put this effort in.
Well, if my doctor recommends something and I find a study that contradicts his advice, then it is not easy to have a conversation about the data with him. This has been true with all doctors I have seen through life, for myself or family members. Recent example, a discussion on hormone replacement therapy and blood pressure. They simply reassert their original recommendation. It just seemed like Scott here would be different and welcome a deep discussion.
In my experience, most doctors are working under intense time pressure, and are basing their recommendations on whatever it says on UpToDate. They may or may not be able to engage with you on the substance of the article you bring to the table. However, making a recommendation that is not supported by UpToDate (or whatever set of guidelines informs their practice) opens them to liability when you suffer a harm.
Well, but if it is so rule-based, a doctor could be replaced by expert-systems software, right?
Matching a diagnosis with a treatment is definitely rule-based. I'm not asserting that this is a desirable feature of the current system, just trying to provide some context for why you might be having frustrating experiences with doctors.
"My guess is most professionals, and an overwhelming majority of laymen, are actually confused on this point, and this messes them up in a lot of ways."--how much of this is just reification as a crutch for computational efficiency given limited time/energy/attention?
The thought processes you are moving away from are simpler than the ones you are moving toward, and docs are pressed for time. Likewise, laypeople are mostly probably trying to make decisions about their lives with framings like 'I think that man may be a narcissist so I probably won't go out on a date with him'
The reifications have costs but also benefits and I'm glad you're digging deeper in your practice and inquiry. I worry somewhat about unintended consequences when categorical terms for dimensional characteristics escape the clinical setting and make their way into the ambient construct stew
As a side note, there are common categories in use for wealth like HNW, VHNW, UHNW, but they certainly don't capture the upper-end variation around someone like Bezos (for whom even 'billionaire' is off by orders of magnitude...)
I agree on a purely computational level categorical processes are similar, but practically they can be much harder. I know doctors who really obsess over whether a patient meets the criteria for bipolar, because they really need treatment, so they try to ask questions in a bunch of ways to figure out if a full manic episode that meets the necessary number of criteria really lasted three whole days or not. Whereas I just kind of get a gestalt impression that they were obviously bipolar, then treat them.
I would suspect it has less to do with computational complexity and more to do with communicational complexity, ie categorical diagnoses are easier to talk about and explain and teach, and therefore most people hear about these things in a categorical paradigm most of the time.
The next time someone asks me about my mental health I’ll feel tempted to tell them that I’m “the Jeff Bezos of absentmindedness”. For a while now I’ve intuitively been moving away from the taxonometric definitions of mental illness so it is nice to read something that really goes into the math of it. Even in the cases where there is a definitive “reason” for the mental illnesses listed in the study, like the flu virus for the flu, it usually seems like it’s either some kind of traumatic brain injury (difficult to reverse for now) or something genetic (impossible to reverse fo now) so holding out for a magic bullet is implausible... It’s all symptom management. But symptom management is often what can help someone get over the arbitrary-feeling “line” between “Person doing poorly” and “Person doing well”!
Thank you for this excellent article. I found the concept of a "resident of Extremistan" to be an excellent phrase for describing someone like myself. I fall into the 2% or less in seven major categories, including autism spectrum and bipolar disorder.
I just signed up here as a founding member after Jonathan V. Last at The Bulwark gave a recommendation.
Statistical question / hypothesis regarding substance use disorder:
Many analytic methods don't deal well with massing at 0 and/or 1 (whatever the boundary condition is). There are large proportion of the population who are teetotalers, and a small proportion of the population of drinkers drive a significant amount of alcohol consumption. I assume (probably incorrectly) that many substances have similar distributions of use per capita/time.
Question - wouldn't this bimodal distribution drive taxonicity in statistical analyses? Despite this, substance use is not cleanly divided in the clinical context where substance use is 1) comorbid, 2) often a coping mechanism, 3) not necessarily problematic.
It seems like language is biased towards categorical thinking - either you choose to use a word or you don't. You need to know from context that it's not what people really mean, that tallness is dimensional. Sometimes it's tricky to hint at dimensionality without being overly vague.
Yeah. I once tried to make a conlang, and one of the things I planned to include was a variety of "intensity modifiers" that let you turn adjectives like "red" into more nuanced constructions like "very red", "kind of red", "arguably red", "reminiscent of red things", "more red than you would think, given what it is", and so on, in order to address this very issue.
it's a decent test for an AI, to see if it understands that. Like if you give a GPT-3 chatbot a height and ask it to tell you "tall or not tall" I wonder how it does
Yes, isn't greater and greater specificity what language has always aspired to achieve? This is OT, but I've been trying to figure out if I'm turning into a cranky old maven who can't stand to see language evolve, or if we are indeed witnessing a rather remarkable period in history in which we are collectively demanding less and less specificity from it.
Social media is the most obvious catalyst for new expressions, but it also heartily embraces sloppiness of execution, asking consumers to intuit emotional meaning from fuzzy group reactions to imprecision. Is there any consensus about whether everyone who enjoys over-using the word "literally" is doing so with tongue in cheek or out of ignorance? Regardless, what is one to do when one really needs a word like literally? Do we have to say "literally literally," since "literally" now has a new cheeky/ignorant definition?
Scott calls the term IED an "acronym," while I always thought it was an "initialism"-- but now I see the dictionaries are allowing the broader definition, which I guess simply means not enough people care about maintaining specificity in this particular category. But I'm getting the feeling the loss of specificity is snowballing these days, like the melting of the polar ice caps. And we're already suffering some of the political consequences of this cultural evolution. Or maybe I'm just becoming a cranky old fart.
This would make an interesting new topic in DataSecretsLox. Here, I'm afraid, it has hit an already almost dead thread, and you'll get not much of a response. There are some smart (sometimes grumpy, but on solid grounds one can learn from!) old men over there (apology to everyone misrepresented!), as could be seen in the discussions around computer interfaces, so as crosspost should be worth it.
*a* crosspost. Why, oh, why is there not way to edit?!??
I think language isn't geared toward specificity. English especially seems to offer vagueness as a benefit. I think of "love" and its thousand plus meanings, or all the other words that have different meanings (another example being hot meaning temperature or spiciness).
Vagueness allows for tentative communication with plausible deniability (there was a discussion of this on SSC once, re flirtation, IIRC), and the everyday diplomacy based on it.
Hence the existence of a spectrum from scientific use of language (where every term comes with a well-referenced definition, in extremis: calculus) to fuzzy … let's call it 'sounding out of an emotional or affective resonance'.
Language does all that. We are the ones to be aware of what to expect/utter in what situation; and a misinterpretation of the situation tends to backfire in every way, from comical to meh to tragedy.
And yes, there is some human-rabbit overlap in sizes.
https://www.catersnews.com/stories/animals/meet-the-worlds-biggest-easter-bunny-and-his-brood/
Answering the important questions here.
my takeaway is that if I catch a flu then I will be telling everyone to stay away from me, for I am a Flu Person
A Person of Flu.
Lol
Is “person with autism” really misguiding? I mean, we already have and use terms such as “people of color”, or “people of size” and I don't think anyone really assumes those are binary categories.
I think the preposition is important here: "of" vs "with".
If you say "person with color" it actually sounds kind of offensive, which I think reinforces Scott's point
I'm a person with mostly pink color, especially if I've been in the sun recently.
For what it's worth, a lot of autistic people reject "person-first" language, though for different reasons than Scott suggests in the post. The problem with "person with autism" (they argue) is not so much that it's reifying autism as a clear category, but that it's presenting autism was something separable from oneself. At least that's how I understand it; my experience in the field is fairly limited.
"People of size" is, at least, quite contentious, and I think this is one of the reasons for that.
"people of X" are in practice used to draw sharp categorical differences - color at least is. of size is probably more fat activists adopting general critical social justice lingo to get legitimacy for their campaign of destigmatizing slow murder.
“People of color” is a special case IMO. It’s a way to describe a non-white person without implying that white is some kind of default or ideal. And while “colored person” might seem to be a reasonable analog of “white person”, it has too much cultural baggage.
I think it does still imply that white is the default. It's also sort of like taking Lothrop Stoddard's view of race and concluding "That's basically right, just flip the normative rankings".
Babies are basically bunnies. Small, young, dumb, cute.
1. Why is CCFI of 0.5 chosen as the border between categorical and dimensional? In other words, it seems "being categorical" or "being dimensional" is itself dimensional - is this true?
2. Question about your practice (ignore if inappropriate) - comparing the post here and on your site, I see you've kept the personal tone, which surprised me. Did you get any feedback from patients/non-SSC-readers about the content there? It might be too soon to know, of course.
You're right, I don't understand CCFI well but I think the 0.5 is arbitrary.
I laughed out loud at at this (#1). Fantastic point.
This is a great point (Scott Lawrence makes the same observation below, and his comments are also worth reading) but I think it's worth being careful to delineate the map and the territory. CCFI is a model. Even though a cutoff of 0.5 is arbitrary (so the model suffers from the problem of the heap) it doesn't follow that the distinction *out there in the world* is dimensional. It could be that "being categorical" or "being dimensional" is categorical, but given a particular case, we have to make a guess based on a dimensional scale because we don't have enough dimensions of data to fully separate the categories. Presumably the 0.5 hyper-parameter has worked reasonably well in the past for delineating cases like the flu.
Ah, that's a good clarification, thanks.
I wonder if the positive feedback loop of addiction makes it categorical. "Propensity to become addicted to cigarettes" could be dimensional, but "is currently addicted to cigarettes" (or "has ever been addicted to cigarettes") could be more like separate categories, because it means "consumed enough nicotine for the positive feedback loop to kick in." How much that positive feedback loop affects you varies, but that's like variance in the strength of the flu which makes the "has flu" lump wider than the "doesn't have flu" lump.
Maybe also relevant that "how much nicotine would it take to set off the positive feedback loop" and "how strongly will the positive feedback loop affect you if it gets triggered" are strongly correlated (I imagine) as two aspects of "propensity to become addicted to cigarettes." So the people who are more strongly affected by that positive feedback loop are also more likely to have triggered it (since that takes less nicotine for them).
My personal impression of autism is that it's both. Aspergers seems to me to be more dimensional, whereas low-functioning Autism (for lack of a better term) seems more taxonic.
I dont have any particular study to back this up, its just more of a result of all the stuff I have read about Autism. Its probably also influenced by my belief that it might be wrong (for social reasons) to lump the two together into one diagnosis.
Why do psychologists think that autism and Asperger's syndrome are etiologically related anyway?
I think the major problem is that Aspergers is a syndrome, the causes are barely understood, and people whose symptoms are right in the middle do exist.
But still, to me it feels like having an unable-to-walk syndrome which includes everything from sprained ankles to loss of legs.
They are unable to come up with criteria that distinguish high-functioning autism from Asperger, but also high-functioning autism from low-functioning autism. That's why they gave it one label in the newest DSM.
In the past, the criteria for distinguishing HFA from Aspergers was based on history – if there was a delay in developing functional language, then HFA; if there was no delay in developing functional language, then Aspergers. That criteria worked about as well as any other criteria in the DSM does – sure, there were practical difficulties (history of childhood language development isn't always available for adults, the parents may no longer be around, and even if they are, their memories of decades ago may be imperfect), and as always there are problems with unclear boundaries (timing of functional language development is a smooth continuum), but nothing that rises to the level of "unable to come up with criteria". Honestly, I don't think the DSM-5 authors actually had a very good justification for many of their decisions, and I think those who criticise their decisions are in the right.
And if difficulties reliably distinguishing Aspergers from HFA justify merging the two conditions, well there are also difficulties reliably distinguishing ADHD from ASD. (A number of studies demonstrate the substantial overlap between the two conditions, where to draw the line between them varies from clinician to clinician, and the line has moved over time.) So if it is difficult to reliably distinguish ASD from ADHD, should we merge them?
It can also be difficult to reliably distinguish autism spectrum disorders from schizophrenia symptom disorders. In adults, they can present with quite similar symptoms. The most important way to distinguish them is look at history – if the symptoms were present in childhood, that suggests ASD; if they weren't, that suggests SSD. So, the distinction is based on history – fundamentally the same as the HFA vs Aspergers distinction was. If that's a justification for merging HFA with Aspergers, maybe it is about time we merged the autism spectrum and the schizophrenia spectrum too?
One of the things I love about this blog is how you pull meaningful conclusions that have fascinating real-world implications out of math that goes over my head (but is still interesting to read an analysis of). I went into this one taking a gamble that it would be interesting to me, and hit pay dirt at the end. Cheers :) and again, welcome back!!
At this point is I just assume anything. Scott writes will end up being interesting
Has someone does the analysis to determine whether psychiatric disorders themselves split into two taxa of taxonic and non-taxonic, or if they lie on a spectrum between the two?
This was exactly my thought. If you look at the CCFI figure, it really doesn't look like the distinction between taxonic and non-taxonic is itself taxonic --- it's more of a continuum.
Which... it /can't/ be, right? Either there's a binary hidden variable or there isn't. That's the strong intuition that goes with this distinction. So one of two things is true. Either that's wrong, and the distinction between taxonic and non-taxonic is itself pretty worthless, and we should acknowledge that everything has aspects of both. Or, the fact that CCFI fails to pick up on the obviously taxonic distinction between taxonic and non-taxonic is a hint that hey, maybe this isn't a very reliable measure.
To rephrase: the thing CCFI measures appears to be non-taxonic. Is that a really bad proxy for a taxonic thing, or is taxonicness itself a continuum?
I think taxonocity is going to be measured along a continuum. Warning: this is hyper simplified.
You could create a bimodal distribution with no overlap, to represent two distinct taxons, and then use a distance function to quantify the average distance a point in peak A and a point in peak B.
If you move those two peaks closer to each other, the distance function would decrease along a continuum even if you never actually intersected the distributions at all.
Now let's say you actually begin to combine the two distributions on the plot. At first, there are still two obvious different peaks (with some overlap as Scott pointed out). At some point these distributions would be largely indistinguishable and there would be some arbitrary "gray area" around which it's unclear whether the two distributions are categorically different or merely dimensionally different.
I agree that the "bimodalness" of a distribution is a continuous thing. But, "bimodalness" itself is at best a crude proxy for "taxonicness". Take the flu example above --- as Scott mentions toward the end of that example, if you actually look at a plot of flu symptoms, you don't see two peaks, so that "having the flu" appears to be a non-taxonic thing. Of course, "having the flu" almost certainly /is/ taxonic, and we'd see that if we plotted "density of influenza virus particles" or something like that instead. There really is some nearly-binary latent variable.
And in your constructed example, the same is true. You can make the distribution unimodal, but it's still the case that there is a binary latent variable. It just so happens that you've failed to see it.
So... I worry that that's what's happening with CCFI. For schizophrenia, for instance, people seem to believe (I know nothing) that it's taxonic. That means that the CCFI measure was just "looking at the wrong plot" (either literally or metaphorically, since I dunno how CCFI works), and that on a better plot, a beautiful bimodal distribution would become visible.
While I don't have time to read the whole thing now, I think this is a helpful part from the introduction of the paper Scott linked to, to begin to build an intuition for how this process works:
To reduce the subjectivity of taxometric analysis, and thereby to
address each of the problems this entailed, Ruscio, Ruscio, and
Meron (2007) introduced a technique to produce comparison
graphs using parallel analyses of artificial categorical and dimensional data. These artificial data reproduced important characteristics of the empirical data (e.g., sample size, number of variables,
marginal distributions, correlation matrices; Ruscio & Kaczetow,
2008), and they could be analyzed using the same procedural
implementation as the empirical data. This yields taxometric
graphs for data of known categorical and dimensional structure,
holding everything else constant. Rather than relying on generalpurpose prototypes, investigators could obtain comparison graphs
tailored to the data and analysis plan in a particular study. This
circumvented the first two problems, using a small number of
prototypes for idealized data conditions that had been analyzed
using just one procedural implementation.
The other two problems were addressed by developing the
comparison curve fit index (CCFI). The CCFI is an objective
measure of the extent to which the results for the empirical data are
a closer match to those for the artificial categorical or dimensional
comparison data.
If you're statistically inclined, CCFI just uses Root mean squared residuals to determine the "error" between the observed distribution and these two theoretical distributions.
"These two fit values are then combined into the CCFI:
CCFI RMSRd ⁄ (RMSRd RMSRc) (2)
CCFI values range from 0 (strongest support for dimensional structure, obtained when RMSRd 0 and RMSRc 0) to 1 (strongest
support for categorical structure, obtained when RMSRc 0 and
RMSRd 0). A value of .50 is ambiguous (obtained when
RMSRc RMSRd)."
The actual binary here is what Scott mentioned about the difference between flu and height. A person with flu is infected with influenza virus. That's a binary hidden variable. If we can't measure it directly or don't know whether it exists, all of these statistical tests on (possibly) correlated attributes we do know exist and can measure are attempts to infer the presence of the actual hidden binary variable.
To some extent, it does just come down to whether this is a useful way of thinking, though. Presumably a lot of people have at least one active influence virus cell inside of whatever skin/world boundary we consider to be within their body, but only at some level of viral load sufficient to overwhelm immune response long enough to manifest symptoms do we consider that person to "have the flu."
Remembering Scott's classic categories are made for man, this only really matters to the extent it changes treatment plans. Knowing infectious diseases are caused by germs means we can treat them by performing some intervention that either kills the germs directly or aids the immune system itself in doing so. If we don't know the underlying cause or whether there even is one, we can only treat the symptoms.
I immediately noted that there seemed to be a discontinuity in the CCFI figure - while it is continuous over certain ranges, there seemed to be a jump in the middle. Is this just an artifact of what was represented? Or, is there some meaning behind it?
For those like me who read the version of this post on Lorien: the only major addition for ACX is section III.
Psychological constructs in general are just low-dimensional approximations of complex, high-dimensional processes. The relevant question is not "are they real?", but "are they useful?".
For a similar discussion, see section "Realist intuitions impede progress in psychology" on page 4 here: https://psyarxiv.com/xj5uq
This is a conventional take which doesn't even attempt to grapple with the true complexities of the issue. The question is not whether current diagnoses are dimensional or categorical but rather whether they exist as meaningful separate diseases at all. And most data points suggest the answer is no, that the current system is a joke. A nosology useful to clinicians for efficient collegial
communicate but with no benefit - and often harm - to the patient.
Mentioning riches as an example of a dimensional variable is apt because it appears to be as useful a variable as depression in understanding human beings (I.e. not). That's because a) it's unreliable - most people's wealth fluctuates, often quite drastically, over the course of their lives. And of course b) it doesn't actually exist - money is a social construct.
When we talk about wealth what are we really attempting to get at? The variable that scientists - and particularly epidemiologists - have found most approximates that is socioeconomic status, which takes into account education, profession.and economic resources.
Depression more than likely is but one pillar of a larger, actually useful category - perhaps "internalizing disorder". Or a more accurate system might blow up the whole thing and not even use the heterogeneous DSM concept of depression at all.
Any system must deal seriously not only with the current in-vogue biological factors, but also must account for culture and time bound disorders and the drastically different rates of recovery of mental illnesses depending on where one is (i.e. westernized vs non westernized regions). When outcomes for schizophrenia are better in sub saharan africa than the US, something is wrong.
See:
https://www.nature.com/articles/d41586-020-00922-8
https://www.researchgate.net/publication/267383152_Counterflows_for_mental_well-being_What_high-income_countries_can_learn_from_Low_and_middle-income_countries
https://wchh.onlinelibrary.wiley.com/doi/pdf/10.1002/pnp.461
Perhaps depression is comparable to pain. 'Pain' is also not a valid diagnosis, but merely a symptom, even though you can treat that symptom with pain killers. A person who is in pain because his leg is broken, needs treatment for a broken leg, not merely treatment for pain, although pain treatment can be temporarily helpful.
Yet a person who is in pain due to cancer, isn't helped with a splint...
Some people may be depressed because their regulation system works poorly. Others may have shitty lives and see no prospect of changing that. These are as similar as a broken bone and cancer.
---
And I agree that context matters a lot too. In fact, disorders are often defined based on dysfunction, so societal inclusion and acceptance can be the difference between something being regarded as a disorder or not. If the government likes to torture people and a decent subset of society celebrates torturers as heroes, a pathological desire to torture can be fully acceptable, if it is channeled in the right way.
Your first point is apt. Much work in the sociology of mental disorder argues just that. Once the DSM in it's infinite wisdom decided to go etiologically agnostic it introduced this issue. In DSM 5 it does try to limit this: "An expectable or
culturally approved response to a common stressor or loss,
such as the death of a loved one, is not a mental disorder."
"Expected or culturally approved response" is a notable qualifier and seems to more reflect capitalism's need for an infinitely malleable population without inconveniently deep desires or attachments than an underlying reality. So, in other words, a form of intellectual tokenism to cultural/contextual factors.
On the second point, again DSM 5 attempts to avoid this, particularly in light of past disasters like the classification of homosexuality as a mental illness. It added the qualification that the syndrome must cause the individual distress, or in old school language be "ego-dystonic". Although there are exceptions to this, notably OCD and many of the personality disorders. Not to mention cases where individuals are committed to mental institutions against their will. So, contradictions abound, there is no unified framework or understanding, just a patchwork quilt marrying the economic interests of the "healers", the legitimation of suffering and moral absolution needs of the population, and the social control interests of those in power.
Don’t forget that someone can be in acute distress, but not agree (either fairly reasonably, as judged by a group of ten average bystanders) or unreasonably (because it will be easier for the aliens to find him there, so they can keep beaming mind control rays at them), that being in a psychiatric hospital offers a good possible solution to their distress.
Also, at least here in Canada, it’s extremely difficult to get someone committed to a psychiatric hospital. They basically have to be sitting in Emerg with a loaded gun in their lap, explaining clearly who they will kill before killing themselves, or one day away from a heart attack because they’ve starved themselves so badly. The involuntary commitment orders are also short and hard to renew.
And like all attempts to deal with complex problems using the legal system, there are big advantages to this, as well as big. disadvantages. It does, though, greatly reduce the use of such measures as a method of social control. Valium for miserable middle class housewives in the 50s was much more effective.
Isn't OCD an anxiety disorder and expressly ego dystonic? There's a separate, basically "Conscientiousness up to 11" condition they call obsessive-compulsive personality disorder, OCPD.
Weirdly, the latest DSM revisions put OCD (along with hoarding) into their own section, took them out of anxiety disorders. Doesn't make any sense to me, as while OCD clearly has some of its own brain weirdness going on, the commonality of using behaviour to avoid/try to reduce anxiety (while actually feeding it, sigh) is there. In the case of OCD and hoarding, the anxiety is around the obsessive thoughts, and the avoidance is avoidance of DOUBT (did I actually turn off the stove properly? might I need this one day?)
Yet another argument for dimensionality.
My understanding is that those with OCD symptoms are particularly likely as compared to, say, hoarding or agoraphobia to not have a problem with it. Even if the latter 2 don't seek treatment, upon being asked they will generally admit it's problematic. But there are case studies of ocd where individuals will design their entire lives around these rituals in highly disruptive and costly (time or otherwise) ways that any observer will consider batshit crazy, but they are fine with it. The case studies generally emerge from them being seen for something else, and this will come up.
Having said all of that, I don't have any particularly deep knowledge of ocd, so I may be missing something. Personality disorders are the more hallmark examples of ego-syntonic, so it may be safer to stick with that.
Either way it's a problematic area. Telling someone with every flu symptom they don't have the flu if they don't believe it and/or if they don't have a problem with puking all day is problematic, but so is the nonconsensual shoving of stigmatic labels by powerful "helpers" onto the deviant.
The APA wants desperately to maintain the appearance of neutrality by medicalizing everything, but the truth is there is no escaping the moral dimensions of human behavior. Such questions can only be avoided to our detriment.
I've been under the impression that there's two obsessive-compulsive disorders - OCD which is an ego-dystonic anxiety disorder characterized by intrusive thoughts, and Obsessive-Compulsive Personality Disorder, which is ego-syntonic and more like an orderly, conscientious personality driven beyond 11.
Yeah, one thing I wish was more discussed in the mental illness discussion is cultural context.
I have Seasonal Affective Disorder. I get sleepy and cranky and low energy in winter, and don't want to do anything. Like most with SAD, I am of Scandinavian descent. It seems likely to me that SAD is less a "disorder" in the traditional sense than it is a reasonable evolutionary defense against harsh northern winters: in ancient times, people who stayed near the fire probably did better than people who went out and played in the snow. SAD isn't something that's "wrong" with me, per se--it's a mismatch between a reasonable biological defense mechanism and the modern-day reality of having to work 9-to-5, even in winter.
This sort of mismatch, or having disorders that only occur in some cultures, or whose symptoms vary depending on culture, seems to point to a good deal of societal influence.
Very much so. There's evidence (beyond common sense) for this on multiple disorders.
Also, recent work suggests that disorders are exaggerations of natural temperaments. And a variety of temperaments is good for group survival. For example a study found that groups that contain neurotics are much more likely to survive than those without because the neurotic is always on the lookout for danger and notices it right away while more positive or laid back people would ignore or not even notice early signs of danger (i.e. smoke in the case of a fire).
But some temperaments are maladaptive to their current environment. ADHD is a prime example. This (1) is a great overview of the evo psych of hiw it used to be individually useful and this (2) recent study found that indeed adhd gene variants are declining in modern populations. One wonders what effect this will have on group survival.
(1) https://pubmed.ncbi.nlm.nih.gov/9401328/
(2) https://www.nature.com/articles/s41598-020-65322-4
Indeed. It seems pretty obvious to me that society is not set up to satisfy our physical and mental needs, which evolved around a very different way of life, but to maximize other things.
That doesn't mean that we should go back to a hunter-gatherer lifestyle, but I think that we have to recognize that fairly normal human behavior can be dysfunctional in today's society.
Of course, a good therapy for SAD is light therapy, which deceives us into thinking it is not winter.
I might not have made it clear enough that this is post 1 in a series. You can find an early version of post 2 at https://lorienpsych.com/2020/11/11/ontology-of-psychiatric-conditions-dynamic-systems/ and see if it addresses some of your concerns.
This is helpful. I do think it strange however that you go from a nuanced complex model of causality to using an oversimplified variable on the other end. As you're aware, there's no such thing as depression. There's depression-anxiety, depression-addiction, depression-heart disease, depression-addiction-anxiety-heart disease - but alone it may as well be a big foot sighting
Why does that matter? Because it renders either false or at best misleading some of your conclusions. For example, you say that bipolar is dynamic but adhd is not. But adhd has a high rate of co-occurence with bipolar, cyclothymia and cyclothymic temperament. So are you only talking about the 2 times in history bipolar and adhd have appeared alone, or are they somehow both dynamic and not dynamic when they join forces?
I made an oopsie - it's borderline and cyclothymia, not bipolar. But the question stands as there is significant overlap in many of the listed conflicting conditions.
This reminds me of a semi-recent post from Freddie DeBoer, on genius.
https://fredrikdeboer.com/2020/11/29/2049/
The taxon-dimension distinction seems important in discussions of talent; while talent varies greatly, "genius" as a truly separate category doesn't seem to exist. But many people, including Freddie there, conflate the question of whether genius is real with the question of whether talent is real.
"doesn't seem to exist".
Can't measure ≠ doesn't exist.
And “doesn’t correlate very strongly with easily-measured things”
The "as a truly separate category" caveat is important, there. I'll never be as athletic as Wilt Chamberlain, but that's true in the sense that I'll never be as rich as Jeff Bezos. Not in the sense that I'll never be as rabbit-y as a rabbit.
This has significant implications for how we should handle extreme talent. If you go digging through the links in the link I posted, you'll see various people fretting over the social implications of saying that some people are geniuses and other people are not. They're right to fret; it's healthier socially, as well as more accurate, to avoid drawing that dividing line.
"You are more talented than I am" is a better way to approach the brilliant than "you are a genius and I am not".
"By their fruits you shall know them". The outcomes achieved by some individuals is so far above others that it is silly to democratize it. Just because they are categorically different does not mean they are another species - that's a straw man.
And the minute one gives an inch in the process of thinking to frets about social implications is the minute one stops thinking with any clarity or honesty. To think is to exaggerate and to exaggerate is to polarize and to polarize has negative social implications.
But they're not so far above all others. For every incredible supergenius there are a bunch of people almost as good, and for each of those people there are a bunch of people almost as good, and so on till you reach unexceptional people.
As for the social implications, well, the facts are pretty clear so it's a good time to think about what those facts mean.
By the same reasoning, intellectual disability would not exist, although it is obvious that below a certain level of intellectual ability, you aren't really playing the same game anymore.
Some intellectual disabilities are clearly identifiable as particular things. Down's syndrome is also called trisomy 21 because it results from trisomy on the 21st chromosome. You either have that or you don't.
But yes, there are disabled people who occupy the same smooth curve as the people we call geniuses.
I was just referring to low IQ, without using any of the naughty words.
If our measure is IQ, then I think there will be people with acute conditions like Down's with the same score as people who are just on the low end of the bell curve without any distinct condition. Both people will be expected to have comparable academic performance, but I think those with Downs would be expected to have less ability to live independently.
Nope; the ability to live independently is not different for two people who have the same IQ, when one has Down’s and the other doesn’t. Lots of other factors at play (education and supports, demands of the surrounding society, whether there are also major physical health issues,,,)
My understanding was that Arthur Jensen found that what might be called "familial" cases of low IQ to be more capable (outside the classroom) than "organic" cases. I can't remember where I originally read that, but in this interview he says most people with IQs above 40 or 50 are "biologically normal" and just part of the bell curve's range. He also says that even with a very low IQ "showing generally good judgment in the ordinary affairs of life should rule out a diagnosis of mental retardation".
https://www.unz.com/isteve/here-s-my-upi-article-on-that-supreme-court
Veryvery low IQ, which we classify as intellectual disability (lowest 2% of pop, w/dig functional impairment) pretty much never occurs randomly or even by normal genetic variation.
There has to be an exceptional cause; genetic abnormalities like Down’s, fetal alcohol syndrome and other teratogens, severe neglect and isolation.... Even most people of very low IQ that’s in the ‘normal’ range have usually experienced something that actively pushes intellectual ability down. Long periods of very poor nutrition....
But the other end of the curve doesn’t seem to be about anything extraordinary besides luck; more a combo of lots of luck within normal genetic variation, lack of factors that could seriously impair that ability, and opportunity to both develop ability and to show it. Plus whatever cultural/historical moment that this person’s ability fits into well.
That lack of down-pushing factos resembles the income–happiness relation. Increased income does not make happy, it only removes causes for unhappiness. And (broadly!) around 60k/y the marginal happiness vanishes, and money shifts into a different value for life ("keeping score" in one's (aspired to?) peer group for example).
That sounds doubtful to me. If there are an enormous number of genes (plus random developmental factors) of small effect and they add up to produce a bell curve, then there will be some people at the very low end without any of those large effect factors (same with at the high end). The main reason for that not to be the case is if there are enough people with those large effect factors to fill up that 2%, and those factors are indeed so large that even getting a tails on every binomial coinflip wouldn't go down that far. My thinking had been informed by what I'd heard about people classified as retarded, with IQs at least two standard deviations below the median. In a normal distribution that would be about 2.5% of the population.
You might find these interesting.
"Complexity perspectives on behaviour change interventions"
https://mattiheino.com/2020/10/19/besp/
Youtube Channel: "Complex systems in behavioural sciences"
https://www.youtube.com/channel/UCR9nYEjzOCzQLjxDgKo0EZA
An argument I've encountered that ADHD "really is" a specific medical condition, and not just a fancy name for below-average concentration skills, is that apparently when you give ADHD medicine to a person without ADHD, it actually makes them more jittery and less able to focus -- IOW the medicine has opposite effects on people with and without ADHD. Is that true, and does the argument prove what it sets out to prove?
That would still work in a dimensional model. Like, imagine everyone has an "ADHDness" score from -10 to 10. And ADHD diagnoses are clustered in 0-10, but medication moves you 10 points in the other direction, and past -10 you get negative side effects. So someone at 5 takes medication and goes to -5, someone who starts at -7 goes to -17 which is outside the normal distribution and gives negative side effects.
This doesn't seem true. Aside from the popular trope of speed users being famously productive while high, which from my limited experience seems true, amphetamine use to get through finals week in very difficult or competitive college majors is definitely real. It may be making people more jittery, but it doesn't decrease ability to focus.
Nope, stimulants make everyone more focussed. That’s one of the reasons we love our coffee, tea and nicotine so much.
People with ADD/ADHD just need more stimulants to get the same effect (with huge differences in how much of what type how often, unrelated to symptom severity, weight, age etc). That supports the dimensional claim.
Oh, forgot the second part; anyone, ADHD or not, who takes too high a dose of stimulants will feel jittery, less focussed etc. Too high just has to be higher for people with attention problems.
Clearly we need a meta-meta-analysis to determine whether taxonicity is a categorical or a dimensional concept.
If you use the same methodology to determine if amputation is dimensional, how does it fare?
This is a smart, entertaining post and I learned a lot. I was also reminded of something that I am reminded of a lot, which is that a lot of very smart people don’t really know much about addiction or at least don’t think enough about the power of words in its weird realm.
The exclamation point after “gambling addiction” I found particularly troubling, and a little snarky. Spend some time at a GA meeting and there will be no question in your mind that it’s an extremistanic not dimensional phenomenon. There is no meaningful line that connects my thrice a decade purchase of lottery tickets and gambling addiction.
My own experience and long-term observations of folks in recovery tell the same story about alcohol. There are cats and dogs and to an alcoholic alcohol is catnip, which lots of dogs might have now and again but does not lead them to massively destructive behavior. Also, sadly, while Jeff Bezos could buy enough (I suppose) ivory back scratchers to exit his personal extremistanic state, the addict has a one way ticket. Pickles cannot revert to cucumbers, etc.
Why do I bother to write this? Because, again in my experience, one of the defining features of addiction is that there is a constant internal dialogue that amounts to “abstinence is an overreaction, I can [gamble, drink, have the occasional benzo, etc.] just like everybody else.” It’s a disease that works to convince the afflicted that they are healthy. So in my view it is really dangerous to casually propagate dimensionality theories about addiction. Down that path lies an enormous chasm of pain for the addict and those around them.
I have no idea how you could analyze this mathematically without any ability to estimate parameters of the actual generating process, but there certainly is a formalism in recurrent dynamical systems whereby some diverge and some don't. The actual sensitivity to each parameter is real-valued and on a spectrum, but "diverges or not" is a strict binary nonetheless.
That seems to be what is happening with addiction. Whatever feedback loop causes behavior to either reinforce and become more extreme or rewards to deaden and repetition to get boring tends toward extremism to the extent that it spirals completely out of control in some people, while converging to some steady state short of that in others.
That is maybe missing in this kind of purely statistical analysis that dimensional traits can produce binary outcomes because "disease" is really a recurrence relation. It's a function not only of the traits we're measuring, but the state of your body at all previous points in time.
Agree entirely.
Me too!
I agree, and had the same reaction to the exclamation point after gambling addiction.
Consider professional gamblers. Consider people that participate in every available lottery. Is there ‘no meaningful line’ between their behaviour and that of addicts? You compare only your extreme to the extreme of addicts and conclude it has to be taxonomic. That’s just using anecdata as evidence.
I’m not sure what I did is meaningfully different from SA’s wealth analysis. Casual empiricism (dangerous!) to be sure. Overall point that addiction exhibits the extremistanic characteristic of modern wealth distribution stands I believe.
"And look what isn’t on here – schizophrenia, which is just a really obvious separate taxon. You know, the condition where sometimes between ages 18 and 25 for men and ages 25 to 35 or so for women, over the course of a few weeks, seemingly normal people start getting extreme hallucinations and eventually devolve into a state where they often can’t live a normal life or even speak meaningful sentences? The taxometricians are saying ah, whatever, it happens to all of us, they’re just the people who it happens to more than average?"
["yes" chad image goes here]
1) Median household income in the article is off by nearly 100% ($63k in 2019) (https://www.census.gov/library/publications/2020/demo/p60-270.html)
2) "Has the flu" in terms of medical treatment isn't categorical based on "is infected by influenza virus or not" - it's an assessment of the dimensional response to being infected/exposed, which may run the whole way from "shrugged it off without even a sniffle or headache" to "death". As a reminder, this dimensional nature of the response to covid is part of what is making it so hard to manage.
3) If your chart is showing 'gender' as being more likely dimensional than categorial, then I think your chart has serious data issues. I myself would use that as a 'sniff test'.
Overall, I agree that looking at the human condition as a spectrum in most cases is very useful, and that it's probably best to intervene only so much as necessary to, as you say, allow a person to go on with their life in a productive and pursing happiness manner. Whether this is best money, or medical (procedure/chemical) treatment, or coaching into personal growth...there are lots of tools.
1) Scott was using median individual income, not household income.
Still off: https://dqydj.com/average-median-top-individual-income-percentiles/
Gender is interesting because while there are clearly binary(ish) underlying variables (does this person have a Y chromosome? Does this person have activated androgen receptors?), they’re not necessarily all that socially relevant. Like outside of “you intend to get pregnant with this person” you shouldn’t really care about the underlying variable(s).
Sort of along the lines of someone can be firmly in the “not flu” category (unambiguously negative PCR test), but their symptoms strongly indicate “should stay home from work” then there’s no real issue with allowing them to stay home.
Can you unpack this a little? Is your take along the lines of "sexual differences only impact reproduction"?
In most cases where you have a reason to care, what you care about are the actual secondary sex characteristics, not the underlying cause. If you're hiring a server for Hooter's, you're not really concerned whether an applicant has two X chromosomes, just that an applicant has visible large breasts and a vaguely feminine upper body, regardless of how they were generated.
I'm not even sure you really care when reproducing. At best, sex is a proxy measure of reproductive capacity as well, since a person can be unable to participate in whatever their half of the process would have been for reasons other than "wrong sex."
> this has another implication: stimulants shouldn’t be thought of as magic bullets that “cure” “ADHD” by fixing the underlying cause, in the same way that Tamiflu cures the flu by blocking flu viruses. They should be thought of as things that affect the underlying stew of variables that cause ADHD in some helpful way.
I don't think this is right. Conceptually, we should be able to say that, among the many dimensions along which we can measure a person, some of them are, by virtue of extreme or unfortunately-combined values, causing ADHD in that person.
And some of them are being modified by the expression of ADHD -- instead of being causes, they are among its effects.
The point of medication is to relieve a problem, such as an inability to see things. You can do that by removing a cause of the problem, and leaving the uncaused effect to disappear naturally (we can call this approach "laser eye surgery"), or you can do it by removing the effect while not doing anything about the cause. (We can call that approach "glasses".)
I had the impression that stimulants are viewed more as altering a symptom of ADHD than as affecting its causes.
I'm curious as to how this might work when there are more than two relevant categories: for example, colds also produce flu-ish symptoms, and the presence of another lump in the middle would move it away from the bimodal setup. I may have to look into this.
Minor nitpick, but you should probably make better figures than the hand-drawn ones on your website, even if the axes are completely 'symbolic' and only serve to prove a qualitative point. It'd look more professional.
I think the point of hand drawing them was to illustrate that these were not real numbers and graphs
Funnily enough, I really liked the hand drawn graphs - especially the rabbit/human one. In terms of communicating the idea it was nigh on perfect (for me..)
Now do the same thing with traditional US denominations for race and you'll understand why it is seen rejected as a biological construct by the overwhelming majority of geneticists and population scientists.
Is it really rejected by the "overwhelming majority of geneticists"? My understanding is that they've never had any problem using the term with other species, but there are political issues with applying it to humans. It is the case that race is not a Platonic discrete category, and is (at most) a much fuzzier and less fundamental category than sex.
> or you’ll get disillusioned and radicalized and start saying all psychiatry is fake.
This is about where I am.
My own experience with trying to get diagnoses and treatment for depression and ADHD for myself and for my kids has been super-frustrating. I know two young men who were diagnosed early with ADHD who later went through a smorgasbord of different diagnoses; one ended up as bi-polar and the other as autistic. My sense is of psychiatrists looking at clouds and saying "methinks it is like a weasel".
Add in the fact that you have to pay $1000s to each cloud-watcher before they can identify the right weasel and the fact that the next cloud-watcher will almost certainly tell you that the previous one was full of shit and it's hard to have confidence in the industry as a whole.
I wonder if, perhaps, this is why so many of us are eager to sign up with Scott's practice. At least Scott is aware of the uncertainty in the field. I fear the unwarranted certainty that so many doctors speak with most of all.
Exactly. It seems to me that psychiatry would be better off if they dropped the pretense that they are capable of diagnosing and instead, adopt a more experimental mindset, like this:
- Based on the symptoms, I think that there is a 60% chance that the patient has X, 30% they have Y and 10% something else.
- Let's do a treatment for X.
- It didn't work, so now I think that there is a 60% chance of Y, 20% of X and 20% something else.
- Let's try a treatment for Y.
- That didn't work either, so let's update to 30% X, 30% Y and 40% something else.
- Let's try a less common treatment for X.
- Hey, that worked, so only now I diagnose the patient with X.
Hanson (Elephant in the Brain) would probably say that the pretense is the point for most people.
Come to Canada, where the health system doesn’t require a diagnosis for the MD/clinic/medication to get paid for, where docs rarely get sued, and few people treat MDs like gods and then expect them to act like gods, and you’ll find a lot of practitioners who work approximately like that.
A lot of people have already identified the seemingly arbitrary deciding line between "dimensional" and "taxon" but it seems to me like there is a little question-begging in the other direction too.
Scott lists the criteria for various conditions, but the very existence of both the conditions and the criteria is, itself, down to some questionable statistical shenanigans.
Before asking whether depression is a categorical thing or a dimensional thing, shouldn't we be asking whether depression is a thing at all? And is it categorically a different thing than ADHD or bipolar? Or did they all just arise from more multi-variate cloud-staring?
This is a good point, because while people’s experiences of these ‘disorders’ are quite different, there’s a lot of overlap, co-morbidity and a lot of treatments that work for multiple, supposedly different, disorders.
I may have to use the "Jeff Bezos of absent-mindedness" line at some point. But beyond that, this is a helpful way of looking at something I've been thinking about on my own account for a while. (Though it would have helped if I hadn't read it on the Lorien website earlier.)
I wonder to what extent these 'objective' categories are just artifacts.
For example, imagine that angriness is a normal distribution, but psychiatrists don't actually test how angry someone is, but they consistently ask the question whether the person beats their partner. People who do are diagnosed with IED, those who do not, aren't.
What if anger is just a normal-distribution, where most people express this in societally acceptable ways, like posting angry screeds on Twitter? What if beating your partner has high societal and relationship costs, which result in high threshold costs. In other words, there is little cost to beating your partner more if you have done so before, but a high cost if you never did it before. This would then tend to result in an artificial dichotomy, that reflects external conditions, rather than the person being diagnosed.
The IED diagnoses would then seem meaningful, because it correctly identifies a 'real category' of people who beat their partner a lot (one of two clear bumps on a graph), but in reality, this is in largely part due to strong disapproval of partner-beating by society and most partners.
If you were to measure anger by number of angry tweets, you might find something close to a normal distribution, so then IED would suddenly no longer seem like a real category.
IED has never seemed like a real category to most people who work in mental health. Except in rare situations of significant brain damage, where the person truly has little/no control.
My criteria is always; does this person ´lose it’ only on people who are smaller, weaker, more vulnerable, who have less power than them? Only in situations where their reputations/career prospects will not be harmed if the victim stays quiet? Or when intoxicated? Then it’s not IED. Which leaves very very few people with IED.
I've been interested in a related topic recently: suppose there's a condition that's truly taxonic, but we live in a world with diagnostic fads and Szaszian malingering. Would we be able to find which people have the real condition?
Think back to the 1990s when every other young girl with vaguely negative body image was tagged with an "anorexia" label. Might this cause anorexia to be seen as dimensional when it's actually taxonic?
Some people claim anorexia is a culture-bound syndrome. I'm not sure which side this favours if true.
I can sort of see why autism might be taxometric. My wife has autism. She's extremely high-functioning and I'm weird enough that an outsider wouldn't necessarily see a huge difference between us, but from the inside, there definitely is. There's basically a social processing module that she's missing. Stuff that to me is trivially obvious to the point that I have no clue how to explain it because everyone just gets it is completely baffling to her. She does a splendid job dealing with social situations despite this, but it's definitely a difference. Likewise with the sensory sensitivities, which I basically don't have.
(Of course, this is just one anecdote, and may not generalize.)
Beyond the distinction between categorical - continuous distribution, there is also a more fine grained scheme, to which you allude, in which the "continuous" category is split into two sub-types: those with long and those with short tails. Short tailed distributions (e.g. the normal or exponential distribution) have a well defined scale (the standard deviation for the normal distribution) which allows you to say whether an individual is average or exceptional, even though the distribution is continuous. Height is an example. For long tails, i.e. power laws, you don't have such a measuring stick - they are "scale free". For example, wealth is power-law distributed: for any 10 people of net worth $x, there is one person of net worth $10x - this makes it much harder to define "exceptional cases" than in the case of normally distributed attributes. Here's my question: which "continuous" psychiatric conditions are long, and which are short tailed?
One place that categorical thinking (about ADHD) has real-world consequences is in academic accommodations. If a doctor signs off that you that you pass the bar for ADHD, you get 50% extra time on all exams, no questions asked. If you're not quite at the bar, nothing. As a professor, I've responded to this arbitrariness by trying to make exams less time-sensitive, but not with perfect success.
If ADHD is dimensional and prescribing medication is a matter of risks and benefits, why do we only prescribe it either EVERY DAY or not at all? Some people would like to have it available to take once a week, for, say, their most tedious task. What are the very serious risks that outweigh that need, assuming they have no history of addiction or heart problems?
I tried to look up the negative effects of taking adderall but they all talk about it as if it's totally different for people who do and do not "have ADHD".
I often prescribe it as needed and I think a lot of other people do too.
Lots of people take their stimulants as needed, including fiddling with the dosage and with whether/when to take another dose.
And lots of MDs know this and are fine with it. If you are prescribed 30 Vyvanse 50 mg, 30 20 mg, and 30 methylphenidate 10 mg per month (as my son is), your doc knows you’re using it prn. Even if the scrip and the bottle don’t say that.
Scott, I'm reading the brief primer, but not seeing addressed why they choose these methods over normal cluster analysis, which is typically what you'd do when trying to decide whether some category is "real" or not statistically. Is it just because they have low-dimensional data? That doesn't seem like a good reason, since that makes cluster analysis even more interpretable if you can actually plot the clusters. "Within group variance is less than between group variance" at least seems more principled and intuitive than "CFFI is greater than 0.5."
I don't understand the statistics involved well enough to answer this, but I'd be interested in hearing from someone who does.
They do actually directly address, just not until the end of the long article. They don't address it in much depth, but rather refer you to other articles. I think this one (https://tpb.psy.ohio-state.edu/papers/beauchaine 2003.pdf) seemed to contain the best explanation, but I'm still not satisfied.
Effectively, the complaint is that use of a clustering algorithm will always yield clusters even along purely dimensional taxa, and there is no way of knowing exactly how many clusters to yield. The reason I'm not satisfied is that presents a good reason not to use cluster analysis to discover taxa, but that isn't what I was asking. I was wondering what reason they have not to use a form of cluster analysis as the test for whether a taxa is categorical or not. That is, don't use a clustering algorithm to automatically discover statistically valid categories, but given you already have categories and a way to construct a distance function over the space of measured symptoms, just test whether between group variance is greater than within group variance along that distance given those categories as groups.
Minor nitpick, Scott uses Taleb's terminology incorrectly. Bezos doesn't live in Extremistan. Wealth is in Extremistan, while height is in Mediocristan.
Mediocristan is where you find all the nice normal distributions which look like Bell Curves. Extremistan is where you find distributions with really long tails (power law type stuff).
I was using Bezos as a symbol of wealth, you agree wealth is in Extremistan and follows a power law, where are we disagreeing?
As I said it's a minor nitpick, but you say "Jeff Bezos lives in Extremistan" Taleb's point is that we all live in Extremistan. And that this has changed recently. That Bezos is not separated from us by his great wealth, that he does not live in a country different from ours, but that we are separated from our ancestors. That, as you point out, this is why our instincts about wealth are so wrong, because we are built for a time when someone couldn't be 5 orders of magnitude wealthier than everyone else.
By saying Bezos lives in Extremistan you imply that we don't and that is Taleb's whole point, that we do, and we don't realize it.
Another good analogy with height is that, theoretically, there's nothing _wrong_ with a short man; but, practically, he's generally going to struggle in life in our current social milieu. In the same way, there may be nothing inherently wrong with someone who struggles concentrating (maybe they're just not interested in the subjects of the current social milieu), but they'll struggle "fitting in". This might be a more tempered way of looking at the often strange spiritual implications of psychology and psychiatry rather than going full Szasz.
Another version of this: Imagine a society where basketball was extremely important, so that your ability to perform well on the court between the ages of 5 and 18 was the most important thing in determining your future success. There's nothing wrong with being short, but on average, taller people will do much, much better than shorter people at basketball, even if there are plenty of tall people who are also not that great at basketball and some Muggsy Bogues-types who are incredible in spite of their lack of height.
Now, imagine that society develops a pill that will make you taller. For people who are very short, it makes life much easier, as it can bring them up to average height. Even a Muggsy Bogues, who can succeed without taking it, would still benefit from it. But at a certain point, you get diminishing returns. Someone who is 6'6" and bad at basketball will not benefit much from being 6'9"--the height isn't the issue.
So there will be guidelines, particularly if there are negative side effects to the pill, but there will also be exceptions. In that case, you may say "As a general rule, a man needs to be under 5'6" to get the pill." A doctor may decide it's not worth it for Muggsy, but it is worth it for someone who is 5'7" but really struggling with basketball. But you would never give it to someone who is 6'1". Knowing that height is a spectrum and that the line between "short" and "tall" is in some sense arbitrary doesn't mean that there isn't an actual, quantifiable problem that needs to be overcome, and that's what's important here.
Great extension, although the idea I'm exercised about is the negative stigma of all of these psychological "problems". Whereas with height, there is very little benefit (maybe for horse jockeys), whereas psychological "problems" may, in some cases, provide benefit such as creativity, artistry, etc. Beyond side effects of these pills, I think there should be some trepidation on the part of the doctor and potentially some agency on the part of the pill taker.
Do you imagine that pill takers have no agency? On what planet? And that most MDs experience no trepidation about this stuff?
People SEEK help with their psych problems because they cause distress/dysfunction. Not because someone put them in a box that says ‘disordered - to treat’.
Sorry, I should have written "and potentially more agency". Agency isn't an isolated thing: if someone is constantly told that they have a "problem", any agency they do have may be distorted. This of course gets into deep and complicated philosophical and cultural questions about defining problematic behavior, what makes people feel they have a problem, and when something really is a problem which is enough to risk negative effects of any psychological treatments (pharmacological or not).
The classic example, of course, is that the DSM used to categorize being gay as a disorder. The methodology they used to undo this change -- extreme public pressure -- isn't very re-assuring.
I just wish that these philosophical issues were more openly discussed and wrestled with.
I would add that the standard, one-size-fits-all, schooling model is neither a natural environment nor a necessary one (there are many alternative schools that allow for self-paced, competency based, or even self-directed education). Yet many children are "diagnosed" with various conditions because "behaving in school" is regarded as a necessary norm. I've run alternative schools for decades and it is routine for me to see students with various diagnoses, medications, and treatments transfer to a more personalized environment and do just fine without the "medications." Their parents had sought out the professional help because the child did not fit into standard schooling. Outside the standard schooling model they were able to learn (sometimes quite rapidly) without being pathologized. Psychiatry is de facto based on unexamined scolianormative premises.
There's a classical logic reason to deny that there is a difference between categorical traits and dimensional ones. Take ADHD for example. If it is dimensional, then there will be cases where you want to say of someone that they are not ADHD, but they are not not ADHD either. They sit in the vague borderlands, with some ADHD symptoms, but not the full suite, or they don't have them very severely. Well, according to the rule of double negation, "being not not ADHD" = "being ADHD". From the preceding reasoning, it follows that the person is both ADHD and not ADHD, which is a contradiction. Since this reasoning will work with all dimensional/non-taxonic traits ("rich", "tall", etc.), it follows that no trait is truly dimensional. They are all categorical/taxonic. Now, it may be a permanent limitation on human knowledge that we can never know the precise boundary between being ADHD and not being ADHD, but there must be such a boundary. If you think, hey, let's just give up classical logic and say there are propositions with truth-value gaps, that leads to problems too. One of these is how to fix the boundary between propositions with truth values and those without without just replicating the whole vagueness problem all over again. Plus it seems, as my Dad would say, like too much sugar for a nickel.
From what I gather the RDoc framework (https://pubmed.ncbi.nlm.nih.gov/26845519/) is an attempt to steer psychiatric/psychological research in the direction of more dimensionality and away from categorization. I would think the advent of digital phenotyping and behavior tracking afforded by apps/bands would enable greater granularity of behavior/symptoms in this regard
A problem here is that many of the drugs that psychiatrists prescribe are controlled substances, so you need clear guidelines to avoid prosecution. Of course there's an obvious solution - stop controlling substances - but in the actual world.
The end reminds me of a conversation I had with Thomas Szasz many years ago. I asked how mental illness could be only a metaphorical "illness" if people who are not functional become functional by taking psychiatric medications. He said, "Do you know anyone who can't function without cigarettes? Would you say they suffer from a nicotine deficiency?" A similarly pragmatic POV.
The level of ‘not functioning’ without cigarettes is far far less impairing and far shorter term than that of someone who cannot function without medics for a bipolar disorder or schizophrenia.
And nobody is saying (at least nowadays) that the meds for such serious mental illness are fulfilling some kind of deficiency.
So this argument is not a valid one now, if it ever was.
The point was not to advance Szasz's argument (which I believe was always part intentionally provocation) but to note the consonance of Szasz's comment with Scott's pragmatism in looking at whether the patient's life can be improved rather than trying to validate their inclusion in a category or to settle the question of the true etiology--biological or behavioral--of mental illness.
I don't think you are properly following out the logic of your argument. You start with flu because we have an unambiguous test, infection with the influenza organism, that shows it to be categorical, you either do have it or don't. If the various statistical tests show it instead to be a continuum, that's evidence not that it is a continuum but that they are insufficiently powerful to tell. That's a straightforward Bayesian argument, starting with a very strong prior, itself based on direct evidence, that people either do have flu or don't.
In the case of gender we again have a test, indeed two tests with almost perfect overlap, genetics and structure, that divides the population into two categories that cover almost everyone. If the statistical tests that were used fail to identify it as category rather than continuum, that's evidence not that it's a continuum but that the tests are sometimes insufficiently powerful to tell. It follows from that that the failure of the tests to identify schizophrenia as categorical doesn't mean it isn't categorical. Indeed, if you have other strong evidence that it is, it gives you another strong reason to lower your confidence that the tests give the right answer.
One could, I suppose, try to avoid that conclusion by saying that what they are measuring is gender, not sex, and it isn't defined by genetics or structure. That's like saying that what you are looking for is not infection with the influenza virus but symptoms of flu. But in both cases, that amounts to throwing away strong evidence — the existence of an unambiguous categorical difference that correlates with the symptoms being observed. How, after all, do you decide what the symptoms of male or female gender are, other than by observing their correlation with other symptoms of the same gender? So how can it make sense to throw out XX/XY genetics, which correlate pretty strongly with m/f gender?
There is a third possibility, that the test can't detect flu is categorical because the symptoms being measured are too weakly correlated with the presence of virus. That doesn't indicate a problem with the statistical test itself but with the data.
That is likely what is going on with gender, where they're measuring something like adherence to social norms that doesn't correlate as strongly with chromosomes as actual secondary sex characteristics and calling that gender, but honestly, who knows? It's a meta-analysis and every study could have been measuring something different.
Not sure if the figure style has a particular pedogogical purpose, but here are some less pixelated versions you are free to use, Scott (and I can fiddle with them further if they don't match the existing ones properly).
https://drive.google.com/drive/folders/1a6yBkVez10cnSMMLgw-DW-ksY5Dj94BB?usp=sharing
Good to have you back.
Nicely done! There are tools to xkcd-ify plots like these, which might be the style Scott is going for. Eg, https://www.dropbox.com/s/4x48pbt3pjnvz2v/xkcd-style-example.png?raw=1 (it would be improved further by using comic sans as the font (he says, non-ironically))
Ed Tufte (an absolute madman/madlad of figure design) once advised me to use Gill for figure text, and although I disagree with him on a lot, that's been my default ever since.
Hard to argue with Tufte! But the point of comic sans is to emulate hand-drawn letters, which is what I think would fit the style that Scott is going for with these charts. Namely, "this isn't real data, I'm just sketching this to make a point".
Or maybe https://en.wikipedia.org/wiki/ITC_Kristen I guess?
Interesting analysis. In order to make it more comprehensive, I'd add the concept of a threshold effect. We see these different types of systems, where reaching a certain threshold in a continuous variable system has a dramatically different effect than any value below that threshold.
The action potential in a neuron is a classic example, where a slightly lower intracellular voltage doesn't trigger the neuron to fire, but then once the threshold is reached a complex series of events unfolds. Another example is phosphorylation of the rb protein, which requires a certain threshold to be reached to trigger the cell cycle. Below-threshold rb phosphorylation gives you no cell division. Once the threshold is reached, the cell will divide.
Regarding autism, the plots that nostalgebraist quotes to argue agains Baron-Cohen's theory at https://nostalgebraist.tumblr.com/post/164069138209/in-lieu-of-a-longer-post-ive-been-planning-to look to me like there is something taxonic going on here (the green ones in Act 2).
The gender thing is cute, but what does it actually mean? Some people are saying that if the test doesn't show gender as taxonic then it's obviously bunk. That's certainly true if they've done the test properly, with at least one factor indicating biological sex. But what if they haven't (as seems to be the case)? Does that mean they're measuring some kind of "gender minus sex"? Should we expect that to be taxonic?
That is my assumption, that they have focused on the psychological side of gender. What I find interesting is if - assuming dimensionality of that trait - most people might be able to play roles of both genders and transsexuality means just male-bodied person with personality heavily skewed towards female (or vice versa). Or in other words: is transsexuality dimensional as well?
it's interesting to think about a difference between absolute and relative categories, sort of complicates the relationship between the dimensional and the categorical.
rabbits and humans are categorically distinct in relation to one another and according to specific criteria. but if you abstract either term from the relation, the categorical definition says virtually nothing about the thing it defines (ie. a certain weight or what have you).. its Diogenes with the chicken..
relative categories are pragmatic constructions which are highly unstable, misinterpretable because of their contingency, hence the aforementioned example. the problem is that, qua the terms of the definition, the relatively defined category can belong to a larger set of things that share the qualities by which it is defined (again, size, shape, weight, whatever) -- whence comes the possibility of some equivocal identification. the relative category can inadvertently create a new dimensionality consisting of the vague objects falling under it (especially if empirical conditions are not ideal).
an absolute category, by contrast, would need to be defined according to terms which do not and could not make something falling under it a member of some more-general set (of arbitrarily non-rabbitish things, or what have you).
and with an absolute or singular definition it need not be a matter of either/or in terms of diagnosis, or even both/and.. it's a matter of necessarily belonging to an absolute category to a contingent degree (which of course could still be 100%). so i suppose the absolute category diagnoses according to singular intensity rather than a bi- or multi-valent belonging in this or that category.
> My guess is most professionals, and an overwhelming majority of laymen, are actually confused on this point, and this messes them up in a lot of ways.
Thank you for writing this. This had annoyed me a lot, back in the school.
Many professors seemed to confuse the map with the territory, although they might have used confusing languages just for convenience' sake.
Regardless, such confusion have propagated to fellow students, and the vicious cycle continues.
Many physical diseases involving complex diagnostic criteria seemed to share similar proneness for confusion.
This kind of reasoning should be taught at med schools.
> I’ll grant them pedophilia – it really does seem like people either are or aren’t pedophiles and there’s something weird and specific going on there.
Total aside to your main point, but (speaking as one myself) I'm not sure if this is true. Certainly I know people with varying levels of attraction, people who are attracted to both children and adults but more to one or the other, people who only realized later in life that they are attracted to children, etc. I think this one could easily turn out to be dimensional.
In other notes, thank you for not conflating pedophiles with child molesters.
I think your comment about there being a lot of variation and the claim that pedophilia might be categorical are not necessarily inconsistent. The question here is: for some observable trait like level of attraction to children, does it looks like there is a bimodal distribution or a unimodal one? It could turn out to statistically look like two populations even if within each population there is lots of variation and even if the bell curves for the populations overlap somewhat (like the flu). And, on the other hand, it could look like one population with a long tail (like hypertension).
Ah, thank you. You're right that the distribution might be bimodal - maybe it's even most likely that it's bimodal - but I feel like we don't have enough information to know.
I've seen at least some evidence for more of a spectrum. I've talked to people with varying levels of attraction: some who could see kids as "cute" but were not motivated sexually, some who had attraction to kids but not as strong as to adults, all the way to those who (like me) are only attracted to kids. There are also plenty of adults who abuse kids but are not themselves pedophiles (according to measures of attraction from penile response to pictures of children). This is typically attributed to a crime of opportunity, or power dynamics, but I wonder if there isn't some attraction present, just at a lower level.
In other words, it wouldn't shock me if you get a big hump around normal adult attraction and then a tapering off, a la the graphs Scott had for hypertension or wealth. I don't know, but I think it's possible.
(All of this ignores, of course, the question of what we're even measuring. Strength of adult attraction? Child attraction? Adult attraction minus child attraction? Adult attraction divided by child attraction? etc.)
If "taxometrics" gives the wrong answer for schizophrenia and gender, shouldn't we just ignore it?
--
You suggest that for "dimensional" traits like wealth or ADHD-ness, we shouldn't expect a specific underlying cause. But extreme values of a dimensional trait seem like they might well have an underlying cause. If you ask why Jeff Bezos is so wealthy, the answer isn't, "well, you know, who can say, it's just a confluence of a bunch of small factors: he worked a bit harder than normal, his parents were a bit wealthier than normal, he saved a bit more scrupulously than most, etc., etc." No, there's one big reason, namely that he founded Amazon. Similarly, I think it's true that people at the true utter extremes of the height distribution have a single specific underlying disorder that causes them to be really really tall or short. It seems like an empirical question whether the extreme values of a dimensional trait have a specific underlying cause or not.
This seems right, but it also seems like when there are specific underlying causes (like founding a successful company), they should themselves be factors that are dimensional instead of categorical. Most people don't found any companies, so there's a big concentration at 0 companies founded, but then there are a good number of people with one small business that are just barely scraping by (think freelancers, ma and pa restaurants), and then a smaller number of people who founded a business with a handful of employees, or multiple small businesses, and then an even smaller number of people with... and then eventually you get to Bezos.
If, instead, founding a successful company was more like a binary distinction, you'd expect that to at least show up as at least a weak "step function" blip on the wealth distribution and make it look a bit less like a continuous.
Machine learning takes a bunch of items with labels ("rich", "not rich") and attributes ("owns more than 5 cars", "reads the New Yorker") and then comes up with a formula ("algorithm") for deciding whether an unknown item fits a label. The formula typically has no explanation (it might have a confidence value for a decision), but there are ways of giving a partial explanation of how it works (e.g., fitting a decision tree to the formula).
The DSM criteria sound like a simplified version of machine learning. And, as we know, machine learning used without care can have all kinds of problems; for example, built-in bias because wrong attributes were chosen or the attributes are correlated with other things that were ignored, such as gender or ethnicity.
Classification models like the ones you are talking about don't actually output a 0 or a 1 for a given input, they output a value in the range [0,1]. If you want to treat the model output as a binary classification, you have to set some arbitrary cut-off point, like 0.5.
Just an FYI, but tamiflu (ostelamivir) barely works at all: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4904189
Irrelevant nitpicking of the highest order but I think your figure for average rabbit weight is low by 2-3lbs.
Interesting but spoilt by muddle headed thinking about 'schizophrenia'. There is a vast literature stretching over thirty years, most of which has nothing to do with taxometrics, which supports the continuum model. Moreover, something that has been overlooked is that the diagnosis groups together a collection of symptoms which researchers have increasingly recognised may have nothing to do with each other, so its possible that some are taxonic (I have my suspicions about hallucinations) but some are not. I carried out a very large taxometric study of paranoid symptoms and the findings wholey supported a continuum model: Elahi, A., Perez Algorta, G., Varese, F., McIntyre, J. C., & Bentall, R. P. (2017). Do paranoid delusions exist on a continuum with subclinical paranoia? A multi-method taxometric study. Schizophrenia Research, 190, 77-81. doi:10.1016/j.schres.2017.03.022
My understanding, as a layman, is that the high correlation between the symptoms is why they're all put under the schizophrenia label (although Scott noted pervasive issues of that sort can undermine the idea of diagnosed mental diseases distinct from symptoms https://slatestarcodex.com/2016/12/14/ssc-journal-club-mental-disorders-as-networks/ ) and that GWAS studies support the idea that they all have a common cause.
Neither of these is correct. Factor analytic studies consistently yield a five factor solution for psychosis: positive symptoms, negative symptoms, depression, mania and cognitive disorganisation. The idea that 'schizophreia' is not one thing and that there are dimensions of psychopathology is pretty mainstream these days. As for genes, GWAS studies have not yielded any genes of major effect and it is now accepted that psychosis is highly polygenic (consistent with a continuum model) and that there is huge genetic overlap between different diagnoses.
Your first point is a solid response to my ignorance. The second is another story. I myself elsewhere in this thread brought up how I had though psychosis resembled certain forms of acute mental retardation and not a continuum like intelligence, and that Greg Cochran told me I was wrong because of GWAS. "Highly polygenic" doesn't undermine the notions of having a "common cause" any more than IQ being highly polygenic undermines the general intelligence factor. If different symptoms are correlated with different sets of genes (i.e five sets for the five factors), that would suggest separate causes.
Having worked with a lot of people with social anxiety and some with paranoid delusions and some with schizophrenia, I have to say; definitely a continuum for paranoia.
Let us not forget that even the most ‘’classic’ symptoms like hearing voices are not uncommon, usually at a less-distressing, less intrusive level, in many people when depressed or under a lot of stress.
But this is a symptom that is rarely asked about, when the person is high-functioning. Hell, if you’re white, middle to upper class, well-educated and not raving, you’ll probably be diagnosed as ‘depression with psychotic symptoms’ rather than schizophrenic, no matter what the progression and dominance of symptoms say. I ‘be seen it happen more than once, to the patient’s detriment.
Oh, forgot, also helps in the situation I’ve mentioned if you’re either female or a male much older than is typical for a first episode.
Scott, on the topic of autism, have you read this paper and what do you think of it? https://link.springer.com/article/10.1007/s40489-016-0085-x
We published a letter related to this topic:
Schizophrenia does not represent the extreme of a normally distributed trait
https://www.cambridge.org/core/journals/psychological-medicine/article/letter-to-the-editor-schizophrenia-does-not-represent-the-extreme-of-a-normally-distributed-trait/263DD068942ABE41AD84A500417B8C3E
I actually tried making that argument about schizophrenia to Greg Cochran, and he replied that GWAS studies really do support the notion that it's just the extreme end of broad variation, like mental retardation:
https://twitter.com/TeaGeeGeePea/status/1328943170957275139
I really do like this piece in general. I am a physician and I also am an individual with high functioning ASD. My problem is with the final paragraph. Language and the meanings assigned to words is a highly variable thing, but as someone with ASD, my "feeling" is that terminology such as "a person with ASD" is much less binary/dualistic than "ASD person." Describing me as "a person with ASD" at least makes me feel like I am on a continuum that includes everybody else. Not that the way I as an individual feel about it is all that important. Just introducing a perspective.
Quite a few people who prefer "autistic person" to "person with autism" do so because they see their ASD as an essential part of their being. And that kind of essentialism troubles me, particularly in light of questions over whether ASD actually exists. Of course, the symptoms, in their immense variety, exists; the question is whether "ASD" is really a useful theoretical construct in explaining those symptoms. Lynn Waterhouse's 2013 book "Rethinking Autism: Variation and Complexity" argues that the answer is "No" – in her view, "autism" is a research dead-end, and we are only going to move forward if we abandon the concept – still research the symptoms and causes, but give up the idea that some unifying concept of "autism" is useful in understanding them. She and her coauthors argue that "The ASD diagnosis has blocked the discovery of valid biological variation in neurodevelopmental social impairment" – https://www.researchgate.net/publication/318463805_The_ASD_diagnosis_has_blocked_the_discovery_of_valid_biological_variation_in_neurodevelopmental_social_impairment – maybe one day the research community will listen to her and we'll actually wave the concept of ASD/autism goodbye, and replace it with a bunch of different concepts instead. What will people who have identified with the concept as part of their essence do when that finally happens? And I think, fear of political pushback from those people is part of why the research community is reluctant to listen to her (and other authors who say similar things).
I do understand your comments and largely agree with them. I can say with certainty that my "diagnosis" was both a blessing and a curse. It provided a very clear understanding for me (but especially for my spouse) of the things that were problematic for me for many years (I am now 52) while at the same time provided an unfortunate "veil" behind which to hide for a time. My self-aware struggle of working through those details over the last 7 years has been exceptionally valuable, and I have emerged from it with a greater sense of wholeness and an understanding of humanity in general, and so in that regard, I am thankful for the entire episode. I think it can absolutely be true that an ASD diagnosis is simply cornering someone (defining an absolute to someone or something that is simply on the the spectrum of normal or standard human characteristics) into a category of dysfunction when really they are simply at a different place of normality. I also agree that the political push-back can be exceptionally severe and often hinders the progress of good science. My point was simply in the way the actual language can be interpreted very differently by those with varying experiences. Thank you for the solid discussion.
It really feels like this linguistic distinction has very little to do with whether autism is a taxon or not and more to do with whether it is considered your defining characteristic or not. When you use the phrase, "person with autism", it's normally because the autism is relevant to the context. "Autistic person" or just "autistic" tends to be thrown around even when the autism is totally irrelevant.
Like, imagine that a newspaper is listing a set of people who had been killed in a natural disaster and that list reads, "...Scott Siskind, a well-known science blogger from Oakland; Steve Thomas, an AI-safety activist from Mountain View; Douglas Lewis, an autistic man from wherever-you-are-from..."
It doesn't really matter whether these classifications are taxonic. How active do you have to be before you are an activist? How many people need to know you before you are well-known? However, the way they are used infers that they are defining. That may be ok if it is that person themselves who wishes to be defined by their autism. It really isn't ok when it is somebody else doing the defining.
It's not really clear to me that what taxometrics is measuring is well-defined. We could of course *define* categorical properties to be ones that pass MAXCOV or some other test, but if we reduce categoricity to that, it's not clear why we should care about it. So what does it mean to "neatly, objectively separate into different groups"?
One answer would be "conceptually dividing things into these discrete categories is the right way to think about them". Spelled out like that it should be pretty clear that this can depend on a lot of things other than the statistical properties of the dataset, but I suspect that this interpretation is a big part of why taxometrics feel like they're telling us something important.
Another possibility would be "the process which generates the observed data significantly involves a discrete random variable". I see two problems with this one. First is that it's not really testable: we can get similar distributions by means of very different underlying processes. For example, if we have a variable X distributed according to a standard normal distribution, then arctan(100X) will be highly bimodal, and if our observables are three different noisy measures of arctan(100X), they'll pass the MAXCOV test, and I'm pretty sure that they or something very similar would pass any other statistical test of categoricity as well*, even though no discrete variables were involved in the process.
The other problem with characterizing categoricity as "the process which generates the observed data significantly involves a discrete random variable" is that the physical processes which actually produce the data are not the same sort of thing as the mathematical models we use to think about them. With a mathematically defined process for generating a random variable, we can say "look, right there, on line 3, there's a discrete random variable", but the physical process isn't always going to have some specific location of the variable that we could point to. If there's a specific gene or something, that's pretty clear-cut, but often there isn't. And when there isn't, whether or not there's a discrete variable involved is a property of the *model*, not the world, and we might get different answers depending on what model we use and how granular it is. For example, you talked about "having the flu" as a binary categorical property, and certainly under many situations it's appropriate to model it as a discrete random variable. But a more detailed model might look at viral count and antibody count as two real variables which change continuously over time. Or something like that; I know very little about immunology. But I'm pretty sure you can't tie it to something as physically unambiguous as "are there more than zero viruses in your body" because someone who fully recovered from the flu and has antibodies shouldn't be classified as infected if they inhale a few viruses.
Maybe these problems have been resolved somewhere in the taxometric literature, but I'm not seeing them addressed here or in the linked primer, and they seem pretty fundamental.
*because arctan(cX) converges in distribution to a coin flip between pi/2 and -pi/2 as c goes to infinity, so statistical tests shouldn't be able to distinguish it from the discrete case for large enough c
Time for the meta question! Is the distinction between taxonic and non-taxonic traits itself taxonic or non-taxonic? What would the CCFI distribution look like for lots of different traits?
There's a tasty and tempting irony in taxometrics. The field says: "Turns out many of these supposed disorders are actually traits that are non-taxonic." Then one is tempted to say "I'm going to care deeply about which traits end up in the binary bins of taxonic or non-taxonic!"
This kind of side-steps the really important question of "when and why do seemingly smooth distributions give rise to important and distinct taxa?"
The answer to this question is nearly always, "there are self-reinforcing effects going on and the taxa are divided by the point in the distribution where the variable will grow over time to where it will shrink".
So your income graph may look perfectly smooth, but there are nevertheless two distinct taxa in people who are living hand-to-mouth, who will see stagnating or declining incomes over time and people who are investing surplus income in future income generation, who will see income growing over time.
Similarly, disease infectiousness may be a continuous spectrum, but there is a big division at r = 1 between diseases that will die out after a few people have been sick and those that will become pandemic.
It feels like many (if not most) mental illnesses have this kind of flavor. The distinction between a person who is depressed and one who is merely miserable is not really how miserable they feel. The distinction is whether that misery compounds itself over time until they cannot get out of bed (and are then miserable about the fact they have not gotten out of bed) or whether it decays naturally as they switch to happier activities to make themselves feel better. Treatments, too, tend to focus on breaking cycles, not really shifting the set point.
It's ironic that this is missed in the article, because your example of the most clear taxon in Psychology is mostly defined by its instability. If your schizophrenics had been unable to speak meaningful sentences since childhood, would you be quite so convinced that they were not just at the long tail of the language development spectrum?
By this distinction, depression, addiction, anxiety, schizophrenia, bipolar disorder, etc. would likely be distinct taxa categorized by the point where they become unstable. ADHD and autism would probably be somewhat arbitrary lines drawn on a distribution.
I'm curious what you think of the quasi-critique I made here: https://nostalgebraist.tumblr.com/post/630848028609249280/slatestarscratchpad-i-think-ive-been-looking
In short, taxometrics doesn't seem well-validated as a statistical technique. Unlike most statistical techniques one sees in practice, it neither has backing from strong mathematical theory, nor from the "real-world stress test" of a large number of people independently using it on different problems. That doesn't mean it *couldn't* work, but feels like it has a closer family resemblance to "algorithms I personally invent for personal projects that seem to work OK" than "anything you might see used by eg Andrew Gelman in a paper."
Separately, I'm unsure it makes sense to apply it in psychiatric patient samples, even if the idea makes sense in some other contexts. From the post:
> After all that, you still have the data you have, which in psychiatric contexts will be sampled from the general population in a very non-uniform way.
> The idea makes sense in an idealized world where your research sample is drawn randomly from the population of All Possible Humans. But psychiatric samples are very unlike that. You can try to remedy that by introducing some control people from the general population, but then you’re introducing a two-category structure into the data (controls vs. patients)!
When I was in college I was depressed so I went to the doctor; they had me fill out a questionnaire and based on my answers decided I wasn't really depressed and basically told me to get over it. One of many experiences that really put me off seeking medical help :(
Could someone please do a meta-analysis of Comparison Curve Fit Index studies to determine if 'taxonicity' and 'dimensionality' are separate categories or just different points on a continuous spectrum?
I'd be curious to what extent the legal social worker professions have driven practical psychiatry toward distinctive categories.
First reaction; YES! So much what I’ve been thinking and teaching and explaining to patients for years.
Then so no no no; eating disorders and substance abuse as categorical? This mistake arises because psychiatrists (and most MDs and most hospital-based psychologists, the ones who do most of the research) only meet the most severe cases, the ones who haven’t managed to stop by themselves or with the help/push of concerned friends, families, employers, AA etc. (BTW, for those most severe cases, there’s very high co-morbidity with early trauma and/or personality disorders. Both also dimensional.)
I’m betting the researchers doing the studies that led to those results in the meta-analysis only included people severe enough to seek/ be brought to professional treatment. Plus we often don’t ask about these issues, unless it’s part of the presenting problem.
Scott, go find the research on how many people have ‘sub-clinical’ ED, alcohol abuse, etc. How many people are ‘overly careful’ about what they eat or how trim they stay, or who binge, but not to the point their teeth are rotting. How many have a year or two or three of drinking or drugging enough to start wreaking some havoc. How many manage to pull themselves back from the brink. To ‘fix themselves’, alone or with the help of a school counsellor, an EAP provider..... to start a virtuous cycle that leads them to a much better place. Without ever talking to their GP about it or seeing a psychiatrist.
"This mistake arises because psychiatrists (and most MDs and most hospital-based psychologists, the ones who do most of the research) only meet the most severe cases."
Very valid point indeed.
> I’ll grant them pedophilia – it really does seem like people either are or aren’t pedophiles and there’s something weird and specific going on there.
As a carrier of this trait, I'm conflicted about this myself.
On one hand, I'm definitely able to fall in love, have sex, and form emotional attachment with adults. I've had a reasonably full love life but none of my lovers ever were under the age of consent. Right now I am happily married with kids (and yes, my wife knows all about me).
On the other hand, I feel definitely binary about my sexual attractions. There are many adult females that are about as attractive to me as a crocodile. For an attraction to be possible, I need to see some hard-to-define childishness in demeanor that doesn't depend much on age but that most adult women (and even some children) totally lack.
So, if I define myself as someone sexually attracted to children (i.e. a binary category with a legal cutoff), then I am on a spectrum: I can experience attraction on both sides of the cutoff. But if I define myself as one attracted a certain personality/appearance trait, which is itself a spectrum, then I am binary: if you don't have this trait I have zero interest.
About autism:
I believe when people talk about autism spectrum, they are talking about a different thing than taxonometrics. What they are saying is that there are multiple ways to be autistic, and all autistic vary a lot on their presentation of autism. They are trying to dispel the popular image of autism as Rain Man, or Sheldon Cooper. This is entirely compatible with autism being its own taxa, with some fuzzyness in the border, just like some people may have the flu, but no or few simptons, or not have the flu but have some flu-like simptons.
Anedoctly, I've seen activists saying, precisely this, that autism is a spectrum, but some people are clearly in the spectrum and some are clearly out.
It sort of seems like the psychiatric profession should move away from the notion of 'diagnosis'. Diagnosis is fundamentally a verb for categorizing. Perhaps it'd be more appropriate to think of things in terms of scores. Patients take a depression test, which gives them a 0-100% depression score, and then you can define ranges of that score that indicate the value of clinical intervention. Functionally that's sort of already what's happening, but re-framing it in this way seems like it might be a better epistemic map projection.
It totally makes sense, that autism would look like the third graph in your article, the one with the flu. Autism is probably a mix of different conditions with various reasons. Some versions of autism are strongly genetically determined. There is a sperm donor, whose all ofsprings are autistic, like 100% https://www.google.com/amp/s/www.washingtonpost.com/health/the-children-of-donor-h898/2019/09/14/dcc191d8-86da-11e9-a491-25df61c78dc4_story.html%3foutputType=amp
Reading this as a physician, I feel suddenly struck by how much of medicine may actually be comprised of things-more-like-height.
Hypertension, as mentioned, is a classic example, but I feel like actually the more closely you look at various health conditions, the less they independently exist as discrete things in the world.
A few examples;
Diabetes (type 2) - basically like high blood pressure. we use arbitrary cut-offs of certain Hba1c measures. The fact that ‘pre-diabetes’ is a diagnosis in itself is telling.
Dementia - very much a spectrum, we use scoring systems, ‘mild cognitive impairment’ being a diagnosis ‘before’ you reach a score “bad enough” to have dementia.
Heart attack - on a spectrum with stable and unstable angina. Yes we have various measures to determine how likely it is that part of the heart muscle is damaged (ECG changes, blood test markers, again arbitrary cut-offs) - but part of your heart muscle dying is not really something that does or doesn’t happen. Suppose 5 myocytes died because your heart was under strain temporarily? - not a heart attack.
Even infections - it’s not really as simple as ‘is this virus or bacteria present in X body system?’ - if you culture somebody’s nasal cavity, or poo, or skin, you will often grow bacteria, and these are not infections. One of the key defining criteria of a pneumonia is whether or not you can see an area of infection on a chest x-ray - again, this is obviously not yes or no.
I think extremely few things really exist in a discrete way (aside from genetic disorders controlled by a single gene, which seem to be an unusual case). We make up categories to describe continuous variables in a way which is most helpful for deciding when to use different treatments. Seems equally true to me for most mental and physical health conditions.
"Is X dimensional or taxonic?"
"Ah, well, it's kind of in between."
ಠ_ಠ
I feel like this missed a good opportunity to make another supporting point: Jeff Bezos only makes $81k/yr salary. (Everything else he has was likely fundraised by sales of AMZN stock to people looking to own small fractions of Amazon... probably 9-figures some years, but probably near 0 some other years. And it also would include a lot of people who are technically broke. Point being, categories are difficult, and easy to manipulate.)
Duuuuuude: taxons themselves fall on a spectrum 🤯🤯🤯
Wonderful text, thanks a lot. There's even a new section in the DSM in which they want to make numbers out of all these complicated diagnoses, I think it's called "emerging theories and models". My colleagues like this a lot. Nice terminology for something that is probably mostly driven by convenience.
In the old days, there were complex psychiatric diagnoses, categorical, and the psychiatrist spent quite some time finding out the problem. The problem: you cannot run the nice parametric statistics, you need proper numbers.
So, rating scales were developed, Hamilton rating scale for depression, anxiety, and so on. The ratings were made by psychiatrists, and they needed to take classes to learn how to do it properly. The problem: it takes so much time. Imagine a randomized study with 200 participants, nobody has time to perform 200 interviews.
Then, more and more questionnaires were invented (the nice term for this is: "patient-reported outcomes"). Beck depression inventory, GAD-7 is also a questionnaire. When I ask my students in class, how do you want to measure X, they almost surely respond: "With a questionnaire". Using questionnaires, the researcher can save a lot of time because the patient is diagnosing himself or herself. More than 20 on BDI -> moderate depression (I don't remember the exact figure). No psychiatrist needed for this diagnosis. And since clinical studies are often collaborative, and every collaborater has a pet scale, many questionnaires were put on the table of the patient. The problem: piles of paper forms that no one wants to type into the computer.
Then, the internet came and everyone bought a smartphone. Nowadays, the patient receive a link to an ever-growing pile of online questionnaires, which you cannot escape until you have clicked on the last of, say, 500 questions. I have seen studies in which, according to my calculations, patients spent hours of with filling out online forms. One of the phd students involved in such projects told me that many patients just put a cross in the middle category because the online forms are way too long. There's also a nice orwellian word for this nightmare: "measurement-based care".
One more funny thing is that there are scientific guidelines from the regulatory authorities in medicine (EMA, FDA) that actually limit the use of all this. E.g., the need for a "primary outcome" in a clinical study, which prevents you from collecting 20 variables and choosing the one that shows most pretty results. E.g., the EMA guideline for patient-reported outcomes in oncology that says, at most 20 min for questionnaire. E.g., the EMA guideline for depression that tells the researchers to do blinded assessment using rating scales. I am digressing, sorry.
There is actually a quite sophisticated "representational theory of measurement" by Krantz, Suppes, Tversky, Luce. The theory was developed to enable measurement even in the absence of concatenation operations such as putting rods together so that the length adds up, or putting two objects in the same pane so that the weight is the sum of the two. In the social sciences, such concatenations don't exist, and Krantz et al.'s theory can be very helpful here to establish an interval scale. But the theory is complicated, so no one makes use of it, neither the proponents nor the opponents of the dimensional approach. Instead, the meaning of a scale is mostly established by its name. If the name of a scale is Novaco Anger Scale, it obviously measures anger. Add a few correlations with other "instruments", and claim that your scale is "valid".
One more funny thing: I think the whole measurement hype in psychology started with intelligence; and early intelligence test were made for diagnosing mental abilities in children. More recently (1980ies onwards), Falmagne and Doignon developed so-called knowledge structures for qualitative assessment of skills, so dancing plus singing is not equal to 2. This stuff is more and more used in e-learning systems like ALEKS that some of our children have to do homework with. In education, they noticed that one cannot make numbers out of everything.
Once I asked my psychotherapist about my diagnosis. His response: "Why would you want to know? I only use it for the health insurance."
I am fervently interested in whether or not you (and others here) have opinions on so-called "positive psychology". For the uninitiated, positive psych is a comparatively recent (1960s or so) effort to use science to understand mental wellness instead of mental illness. In the nutshell explanation I usually use, it's the difference between fixing a blown knee versus training to break the 4-minute mile.
Most of the pos psych stuff promoted (and I do mean promoted) to layman is suspiciously indistinguishable from self-help snake-oil (keep a gratitude journal! don't let failures get you down! develop a growth mindset!), with the caveat that it is, by and large, snake-oil that appears to have, on average, replicable results - per its own (questionable IMO) measures - when people buy into it.
A lot of it is sold (and I do mean sold) as preventative medicine, but I think it fits great with my 10-minutes-old understanding of this taxometric distinction. If most people are not so much afflicted by a mental disease as they are uncomfortable or disabled due to their position out on the tail vis-à-vis anxiety levels, it makes sense that sometimes mental health-oriented boosters /could/ help just as much as, or more than, mental disease-oriented corrections.
The evidence is chaotic soup served with statistical smoke-and-mirrors, but with my methodological background, I've blamed it mostly on early commitment to suboptimal (proxy) measures - not so much where you draw the line between tall/short, but whether or not the yardstick is remotely objective or validly measuring the phenomenon you say it is. Now I'm going to be turning over in my head also whether or not it's a case of: "My guess is most professionals, and an overwhelming majority of laymen, are actually confused on this point, and this messes them up in a lot of ways."
Or am I overly skeptical?
Homelessness is probably categorical enough that "person experiencing homelessness" may be more appropriate than "homeless person" if you care just about sending the right signal.
(Since it takes more bits to explain disagreement than to indicate agreement, and positive reinforcement is useful when true, please take my disagreement here to indicate that any portion I _haven't_ disagreed with is a portion that I agree with.)
You say that "I think a lot of people still want psychiatry to deliver the single [cause of a given psychiatric phenomenon]. It’s not going to be able to do that." I don't think the fact that a given phenomenon is dimensional means that this is impossible; I would read it as meaning that the root cause must also be dimensional. To massively oversimplify the brain, let's say that all other things being equal an increase of X% in the average activity of one's Anxiety Gland produces an X% increase in one's reported anxiety levels, and that all medications which affect anxiety are ultimately things that have an impact of reducing Anxiety Gland activity by some amount. (The stuff that can impact the activity levels of the Anxiety Gland may be complex and multivariate, but I don't think this is different from categorical issues - if there are developmental failsafes so that N out of M mostly independent processes have to fail in order to produce a Categorically Abnormal Anxiety Gland, otherwise the development of a Normal Anxiety Gland is an attractor state, I'd still call Categorical Abnormality of the Anxiety Gland the "single cause", especially if it was what could be affected by interventions.) This would still be a single cause; it would just be a single dimensional cause.
You also say that "If most mental disorders are dimensional variation rather than taxa, that kind of makes the DSM look pretty silly, doesn’t it?...All of this is predicated on the idea that [there are] specific thing[s] called [disorders] that you either do or don’t have." I think another way to regard the DSM, or at least what an idealized DSM could be, is a manual of best practices for tradeoffs which are codified as acceptable at arbitrary cutoffs, much like your hypothetical Sanders tax plan is an arbitrary cutoff made for practical purposes. If a patient has more than X% excess Quality, then the profession regards it as reasonable to experiment with certain interventions which fall under the banner of "Interventions for Excess Quality Disorder", but below that cutoff they think it's not worth the risk.
In this case, it would be good and necessary to renegotiate the definitions of Excess Quality Disorder as new information came up, even if "Excess Quality Disorder" is an arbitrary cutoff. Let's say that new research comes in indicating that Intervention A for mild Excess Quality Disorder is more harmful than previously expected; in that case we might move the boundaries of Excess Quality Disorder to reflect that we want to be more careful with it. Or maybe we discover that while our cutoff was X%, people with (0.8 * X)% excess Quality have a reduction in quality of life greater than we previously thought, so we move the boundaries in the other direction. In this case, "Excess Quality Disorder" is perhaps an inferior category to "Eligible for Intervention {A,B...Z}", but may be worth using for convenience, communication, or research.
Autism, like height and other dimensional traits are influenced by 100s or more genes, each with a small influence up or down. So traits that are influenced by relatively few genes a larger amount each should be more categorical, e.g. schizophrenia (if my impression of schizophrenia is correct).
One challenge I've personally experienced with definitions for psychiatric diagnoses that are based on multiple dimensions is that people tend to attribute all the (categorical) symptoms to people with only enough of them to fit the definition.
My experience is with autism, or at least autism-spectrum disorders. People are diagnosed with autism based on possessing characteristics such as problems with social interaction and communication, and repetitive behaviour or restricted interests (think: Rain Man). My son was diagnosed as "on the spectrum" at a young age. This meant that teachers and other professionals would assume he had all the most common characteristics, whereas in fact he had only a few, and this meant their approach was often not appropriate at all.
This happens all over the place, of course: it's the problem of "natural kinds". All instances of Democrats, ice creams, and churches are not alike in their categories on all dimensions. Politics is often a difficult thing not least because it forces hard demarcations where in reality they're fuzzy (I vote for party X because it's X or Y, not because I believe everything that X profess to believe).
We cannot carve the world at its joints, because they're in our mind rather than in the world. The same is, perhaps unsurprisingly, true of the mind itself.
Thanks for the fine exegesis. I have practiced psychiatry for many a year. DSM III came out when I was in medical school. It sought to make psychiatric diagnosis, which was vague and overly influence by psychoanalytic theory, more objective, but using description and taking away theory. It was felt essential to make psychiatry a legitimately medical specialty, and at the time it was hailed as a triumph. Alas, they threw out the baby with the bathwater. All of the useful tools of personal history, development, personality and temperament were junked. But whatever has been gained from categories makes it harder to treat patients as individuals. (Just ask the insurance company flunkies who rule over the prior authorization domain, and decide how many sessions and which medications are "medically necessary.") DSM IV and V made matters even worse. Not only are the debates about where the cutoffs are for a disorder inane, political considerations have tainted and even overwhelmed whatever medical legitimacy the descriptive categories might have had.
I have long been reconciled that my profession will never be as objective as brain surgery or cardiology. No matter how you dress it up, psychiatry is as much art as science, and I like it that way. As much I look forward to advances of neuroscience and pharmacology, the DSM ain't science, and Big Data tells a lot of Big Fibs.
I appreciated the argument on person-centred language. I've not seen this argument brought up in this way vs "recovery oriented" language. From a medical model it probably makes more sense, particularly when charting, to not use person-centered language.
I’m surprised to hear that narcissistic personality disorder is generally considered by psychiatrists to be categorical rather than dimensional. I’d love to learn more here.
It intuitively seems like people vary on a spectrum in terms of how selfish, egotistical, etc. they are. A lot of people certainly seem to have subclinical levels of narcissism.
Is it that narcissistic personality disorder is something radically different from the personality trait normally referred to as narcissism?
I liked the mention of extremistan. It made me wonder—
*Are* the distributions of psychological variables (e.g. anxiety) fat-tailed (e.g. power law distributed instead of bell curves)? If so, that would maybe be relevant to whether and why people underestimate how anxious GAD people can be, etc.
A bizarre, very minor thing: when I load this page, it says "Jan 28" as the publish date, then a second later, it switches to "Jan 27" .
This is really interesting, but as someone who has ADHD, the idea that ADHD specifically is dimensional seems to directly contradict my experiences. The "symptoms" that get ADHD noticed and diagnosed tend to look like just having an unusual amount of trouble paying attention, the way Jeff Bezos has an unusual amount of money, but there's a slew of other things that have no reason to correlate with ADHD the way they do unless we consider them side effects of an underlying categorical difference.
If I just have an unusual amount of trouble concentrating, why does Adderall make me sleepy? Why does fidgeting help me think? Why are boredom and the perception of failure almost physically painful, in ways that confuses my non-ADHD friends when I describe them? Why do I share these traits with my roommate, who doesn't have difficulty concentrating at all, but has enough symptoms of hyperactive-type ADHD to also get a diagnosis? Why is there enough of a correlation between hyperactivity and inattention that the combined type is even recognized?
There's no reason inattention would correlate with these other traits without an underlying cause. A non-ADHD person who had a short attention span probably wouldn't also fall asleep after three cups of coffee or cry because they got mildly criticized at work.
I suspect some of the confounding findings have to do with the selection of variables that are included in the analysis and how they distribute through the general population in realms unrelated to the ‘condition’ being investigated. I don’t have the time to think through the implications, but further study of the efficacy of the statistical method for separating behavioral disorders is definitely warranted.
Having thought about this statistical method some more I wonder whether it could be used as a tool to improve our ability to diagnose different conditions. For example, if you add or drop certain diagnostic criteria, do you raise or lower the category score. If the criterium lowers the score, perhaps it shouldn’t be included in the diagnostic criteria.
tl;dr: A secret variable does exist, but you can't read it. [we might be in the future, though]
You can't avoid false negatives, but in many cases, you can definitely be certain that you don't have a false positive.
[according to Dr. Russel Barkley, who is a famous ADHD researcher]
That is not quite right. There actually is such a variable and it can be 1.
ADHD is brain damage in five specific affected brain regions, that predictably results in a 30% delay of executive functions for your age. In 2/3rds of the cases, this is genetically determined.
And there are also acquired cases, where it's known that strep-bacteria causes an autoimmune overreaction that causes that brain damage.
And yes, ADHD is highly comorbid with other things. And yes, SCT might be another attention disorder, that's separate from it, is not as treatable (yet) and less well understood.
[and having SCT implies 50% chance of having ADHD as well]
And yes, other kinds of brain damage also can lead you to present with ADHD symptoms.
And all of the above is not universally known or accepted in psychiatric practice.
But ADHD is actually a taxon.
The variable exists and you might not be able to reliably say that someone is a 0.
[unless you find some other disease or environmental cause...... like a kid playing Fortnite all day in school, which is an epidemic in its own right]
After all, the space between the variable=1 population bump and the majority of the bell to its left is not empty.
BUT...... you can and should be quite certain sometimes, that you do have "the real deal" in front of you, by looking at the parents or grandparents and seeing them have it as well.
Also seeing the "paradoxical stimulant effect" (stimulants usually don't make you calmer) would provides evidence for a "1", as well.
source:
excellent playlist "30 essential ideas you should know about ADHD" by Dr. Barkley on recent research into ADHD:
https://www.youtube.com/watch?v=G2u8E5UqEHU&list=PLzBixSjmbc8eFl6UX5_wWGP8i0mAs-cvY&index=7&ab_channel=AdhdVideos
I agree with the observations you cite, but not with your conclusions. "The space between 0 and 1 is not empty, but at 1 you can be certain to have the real deal" (hope I paraphrased correctly) could be said about any psychiatric condition, even if their neural substrates might look less specific than what we know about ADHD so far. You could actually say that about intelligence ("If someone shows to be very smart, had smart parents and a brain that's different so-and-so, you can be certain to have the real deal").
Ah, been a year since I wrote that. Had to figure out, what I was on about myself first.
And then reread the post to remember what Scott was on about, so I hope I'm doing myself justice :)
So "being smart" is not a taxon, since IQ is dimensional.
If there was a gene that always puts you in the 120 to 140 range, no matter what, then that would be a gene that makes you smart. It would be a "fundamental hidden generator" for being 120-140 smart and a Taxon in its own right. But the 120 to 140 range itself would not be a taxon.
There probably are neurological substrate differences for IQ, but they great many "fundamental hidden generators".
ADHD meaning the thing that causes the statistically-visible (but not individually detectable!) brain-differences also has a "fundamental hidden generator".
But there are other things that can often/sometimes look like ADHD, but are something else. SCT or depression (though the latter would be a botched diagnosis probably, but diagnosing stuff is still hard).
So if you see a kid with ADHD symptoms, but no parents have it and they don't react paradoxically to stimulants? Maybe it's still ADHD. But keep more of an open mind, if something else might fit better. And if you find SCT, you can quickly accept that as a sole cause and possibly dismiss ADHD.
If they do have relatives who fit the ADHD type and they do react paradoxically to stimulants? Well, then you have enough evidence to be quite confident that they indeed have ADHD. Sure, you can look for other stuff too. But even if you find SCT, you'd assume first that it's a comorbidity instead of being the sole cause for the pathological behaviour. And keep treating the ADHD.
Even though ADHD is a taxon (has a "fundamental hidden generator", cause brain averages being the cause act as one), we don't really know whether this is the case for SCT.
In the end, the recommended drug regime is not too different between the two.
So I think, the psychiatrist would have to be extremely detail-oriented and knowledgeable to notice this. I don't think Scott does.
And it's also possible, that this distinction is proven enough yet, that it should be standard practice. (and partly that's politics)
It might not even matter, because you pretty much cycle thru the same drugs and stop when you find something that works. It matters only with which drugs you'd want to try first, AFAIR.
Hey, sorry, hadn't looked at the date and for some reason your comment showed up at the top for me, but thanks for replying anyway!
IQ is dimensional. What prevents us from conceiving ADHD as dimensional, as an "ADHDness"? It seems to be that attention deficits come on a wide spectrum of severity and, as you mentioned, can have different causes. I am highly doubtful that we have the diagnostic instruments necessary to reliably differentiate all these conditions, which of course doesn't disprove that there might be a "fundamental hidden generator" for what we call ADHD, but which makes it difficult to find said generator.
What I'm effectively saying is, not just is Scott not extremely detail-oriented and knowledgeable to notice this, nobody is, because the necessary knowledge doesn't exist.
If it finally does exist, I see two ways this could end up in our psychiatry books:
1.) Either we identify distinct subtypes of brain disorders that each get their own names, perhaps under an umbrella term like "disorders with attention deficits", similar what you are already doing with "ADHD" and "SCT", though I don't think a single one of those subtypes should be called ADHD, because they'd all share some elements of what we now call ADHD, or
2.) We understand it as something like "ADHDness" and treat it like a dimensional construct like intelligence.
Whether we lean towards 1) or 2) would not just depend on the evidence, but also an what kind of granularity we want / is helpful for helping people. (Heck, on the same basis we might even identify "Taxons" of intelligence if we janked up our granularity / resolution ABSURDLY high)
In the end I agree with you that, as things stand right now, we have to rely on trial and error anyway.
I admittedly lean heavily towards "ADHD as a dimension" - a case made e.g. here: https://pubmed.ncbi.nlm.nih.gov/25957598/
But I would love to read the case against that, so if you know of any research in that direction, let me know.
I got the impression of ADHD being taxon-like from the playlist here:
https://www.youtube.com/playlist?list=PLzBixSjmbc8eFl6UX5_wWGP8i0mAs-cvY
It's been a while since I viewed this. And I do not know what the current state of research is. When I wrote this a year ago, I might have been able to argue this confidently. And would have cared, because this ADHD-info and the taxon-definition was pretty fresh for me then.
Now I don't really wanna.
Irrelevant for me personally, whether it's a taxon or not.
I just happen to believe so.
Concern about the height example: what if there is a height gene H which can be 0/1. Suppose both H=0 and H=1 lead to unimodal (Gaussian?) phenotype height distributions. If you have a mixture model of this reality then the overall population's height distribution could be unimodal (Gaussian) as well? How can you distinguish this reality from the reality where gene H doesn't exist?
Assuming the height phenotype variance is high enough for both H=0 and H=1 and their means are close enough.