The central point of my prior post on the subject of race and intelligence was that the proposition that differences in performance on IQ tests between various racial and ethnic groups can be materially explained by differences in the genetics of the groups is unproven. A substantive complaint of those who make what I call in the post the “econometric” argument (as opposed to the “physical mechanism” argument) for this proposition is that the hereditarians keep knocking down hypothesized environmental explanation after environmental explanation for difference in racial group IQ test performance, and that therefore the remaining “space” for a non-falsified environment-only theory has become so narrow and twisted that any environment-only theory must be extremely ad hoc and counter-intuitive. In contrast, they argue that the elegant genetic theory keeps passing falsification tests. The hereditarians claim that the environmental theorists seem like they will just keep throwing up any objection to avoid drawing natural conclusions from the data, and that therefore the environmental theorists have moved beyond legitimate scientific debate to pure denialism.
On one hand, it seems to me that there is something to this argument. To the extent that the hereditarians have, in the face of massive social and professional disdain, disproven the crudest alternative theories, they have done a service to science and society. On the other hand I think they have drastically over-stated their case, both rhetorically and substantively. I think it is quite possible to present an environmental theory that conforms to current finding without being either ad hoc or counter-intuitive. Here goes:
As a starting point illustration, consider the following type of natural experiment that is well-known in the research literature, but less frequently noted in the public debate: practice tests increase measured IQ – a lot. Taking one practice IQ test raises average IQ on major IQ tests by about 7 points (~0.5 STDEV). Think about that: I can close half or more of several widely-discussed IQ gaps between groups just by letting the lower-scoring group take one practice test. Now, there are huge limitations to this: scores don’t keep improving as a subject takes more practice tests; it doesn’t appear to create lasting gains; and, importantly, it doesn’t improve g, which is to say, that it doesn’t create the ability to answer a more generalized set of questions across a variety of tests. In the limit case, if I gave someone an answer sheet to an IQ test and then had them copy these answers on the test form, I could create an arbitrarily high IQ score without increasing g at all. That is, I would presumably produce no increase in the subject’s ability to answer as-yet-unseen relevant questions.
But now consider the example of the reverse digit span question, which has been an important component of many IQ tests, and is highly predictive of overall IQ. In this question the subject is presented orally with a digit sequence (e.g., ‘76138’) and asked to repeat it backwards. Additional sequences of increasing length are presented until the subject can no longer successfully complete the task. Try it – it’s harder than it seems like it might be, even with short sequences. Now, when next presented with a sequence, silently repeat the number twice to yourself, and then visually imagine it written in a bright color (also try the alternative trick of imaging dialing the number on a phone keypad, which works better for some people). Now, as you get to longer sequences continue this procedure, but also “chunk” the sequence into sub-sequences of three or four digits each. Practice this repeatedly. If you’re like me, this will increase your reverse digit span. Congratulations, your IQ just went up – feel smarter?
A valid complaint about this is that we’ve just gamed the question and haven’t really increased your g. To be fair, though, I’ve just improved your ability to answer a whole class of questions, rather than just a single question – we’re clearly operating a higher level of abstraction than just rote memorization of a given list of answers.
But now think about moving to a yet higher level of abstraction: the ability to invent such tricks in the face of as-yet unseen question classes. In the case of reverse digit span, it would be the capability to invent some kind of (likely unarticulated) processes like the ones that I have described on-the-fly when presented with this question, never having considered this question until that moment. Surely at this point we are describing something in the neighborhood of g. But ask yourself this: do you think that a person would be more likely to invent such processes on-the-fly after spending 17 years immersed in a culture that demanded some combination of rote memorization of often unintelligible sequences, frequent use of numbers and constant testing than someone of identical genetic endowment who had not? Does this description remind you of any specific cultures?
If there are cultural environments that provide experiences that, at a high level of abstraction, develop a set of mental skills that can be translated on-the-fly to create “tricks” that enable someone to answer even highly g-loaded previously-unseen classes of IQ test questions, we can easily see how such difficult-to-quantify cultural influences could increase measured g. But just as we might infer that there may be some common innate characteristic g at the individual level that is not obvious upon inspection but appears as an artifact of the subject’s demonstrated level of ability on lots of superficially unrelated test questions, why could we not equivalently hypothesize that differences between IQ scores of various cultural groups could easily be (in part) the product of such cultural factors that demonstrate measured impact across seemingly-disparate test questions: what we could call “culture g.”
I find this hypothesis to be neither ad hoc nor counter-intuitive – in fact, it’s not even especially new, as it lines up well with folk wisdom that predates the modern era of IQ testing. It is not falsified, as far as I can see, by any major research findings. None of this is to say that it is true, or even more probable than some genetic or environmental alternative; merely that one can construct an environmental theory for specific group differences that is neither falsified nor implausible on its face.