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Ramblings on IQ and differences in variance - Accretions

Fata Morgana
2008-06-23 21:21
Ramblings on IQ and differences in variance
deconstruction, feminism
I came across an interesting New Yorker article today by writer Malcolm Gladwell exploring the phenomenon of "IQ drift" over time -- there's a steady increase in IQ scores year to year, enough that the standard IQ test has to be re-normed every twenty years or so. The implications are that our great-grandparents all had IQs of 70 ... or that IQ isn't as rigid and hereditary, and testing isn't as accurate, as we are often led to believe. (He presents various evidence for the fluidity of intelligence; it's a good read.)


I also read another interesting piece, written over ten years earlier, on the connection between racial differences in sports and gender differences in math.


It turns out that there are racial and gender differences in the variance of several heavily-contested skill distributions, though the means are the same. For instance, black athletes have higher variance in athletic abilities than white athletes, and boys have higher variance in math abilities than girls, which account for the preponderance of the former in upper echelons (as well as a preponderance of them at the lower end, but this isn't discussed as much). Thus, while the mean ability between the two groups is the same, the distribution is flattened for blacks regarding athletics and for boys regarding mathematics.

Gladwell then discusses how the factors affecting ability are both environmental, as evinced by the differences in populations with the same ethnic heritage but different environments (e.g. Jamaicans of Nigerian descent vs. Nigerians), and psychological, as he saw for himself when he ran track and encountered the black-athlete stereotype. But they are not genetic: the evidence for genetic differences breaks down when environmental factors, such as the training conditions for athletes, the dietary history of medical patients, or the scholastic expectations of students, are taken into account.

Part of the psychological component is one I've witnessed myself: believing that blacks are better at sports than whites, or boys are better at math than girls, becomes a self-fulfilling prophecy for all involved. Moreover, those (relatively) few whites who excel at sports or girls who excel at math are usually believed (both by themselves and by others) to excel because they work hard and not because they are innately talented (what Gladwell calls "learned helplessness"), while blacks who excel at sports or boys who excel at math are believed to do so because they are "innately" good at it. Another is an effect common in the hacker community as well as among athletes -- a particular kind of focus, often to the exclusion of many other things, on a narrow set of goals and values -- a difference among different groups regarding what one is allowed to care about or become obsessed with.

So there are certainly consequences of these differences in variance, but why does it happen in the first place? Could it be that the higher variance in men regarding intellectual abilities be attributed not to genetic factors, but to relative permissiveness toward boys and control toward girls? Further, would this explain well-documented effects such as the gender difference in attribution bias or vulnerability to stereotype threat? This control is exerted in thousands of small ways; for instance, studies have shown that girls aren't allowed to roam as freely or as far on playgrounds as boys when parents are watching, girls aren't allowed out alone as much as boys throughout their childhood and teenage years, and "girl" toys tend to be more passive and ritualized while "boy" toys are more active and flexible in use. Also, girls are told to sit quietly and take up as little space as possible, they tend to be praised for being pretty while boys are praised for being smart, and in junior high it seems like girls enter a labyrinth of social norms that boys seem to be able to more easily escape. (I could be wrong on that last one; I was a girl, not a boy.)

But of course, all this begs the question: where did these behaviors come from? Perhaps the restrictions on girls come from a (perhaps irrational, almost certainly self-fulfilling) fear about girls' safety. But then where does that come from? Is it turtles all the way down -- is it all one social construction after another?

While the "social construction" theories so popular in social science recently do reflect my own observations about the world fairly well, the idea that culture, gender, race, and myriad other things are "simply" socially constructed masks their indelible marks on us all. Sure, these things might be socially constructed, but that doesn't mean that we could feasibly wake up tomorrow and do it all differently. Patterns of social behavior become habit, and habit becomes something stronger -- a set of assumptions, or what French social philosopher Pierre Bourdieu would call "doxa" -- the background we all take for granted upon which we can define whatever "orthodoxies" and "heterodoxies" we want. (For instance, the abortion debate in the U.S. has the "doxa" that killing a person is wrong, and then goes off to argue about when a fetus becomes a person. In Japan, in contrast, people widely agree that fetus is a person, but also that abortion is acceptable. So after having an abortion, one is expected to build a shrine for the fetus's soul.) There are shifts in this "doxa," but if I've learned anything in my brief training as a social scientist, it's that social change is really hard. (For one, if it were easier, it would happen a lot more.) Sure, it happens, but it's generally very slow and full of resistance -- if Kuhn taught us anything, it's that the best way to achieve a consensus change in even scientific communities, committed to being as objective and rational as they can, is to just wait until those who resisted the new paradigm die off. So if higher variance among boys than girls is due (at least in part) to the relative freedom boys enjoy, and boys enjoy relative freedom because there is less fear for their safety, this could very well be due to one wave of social construction after another.

While this recursive answer is also not satisfying, it's about the best I have. Though I know I risk starting a flame war on this contentious subject, I still venture this question: what do you think?
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2008-06-24 21:48 (UTC)
(no subject)
there's a steady increase in IQ scores year to year,...The implications are that our great-grandparents all had IQs of 70 ... or that IQ isn't as rigid and hereditary, and testing isn't as accurate, as we are often led to believe. (He presents various evidence for the fluidity of intelligence; it's a good read.)

Can you explain to me why a steady increase in IQ scores from year to year implies that IQ isn't hereditary? That fact suggests IQ has an environmental component, something which I don't doubt. But it doesn't show that the differences within a group raised in a similar environment aren't due to genes.

(It does seem a little fishy, though. It doesn't quite make sense to suppose that our grandparent's generation was less smart than ours. You'd expect to see some other indications that that this was so, besides IQ tests. However, the difference in scores could reflect differences in literacy rates and how much language is required for day-to-day business or something.)
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2008-06-25 00:33 (UTC)
(no subject)
Morgan, have you heard of Ask A Scientist - that monthly geek-hipster thing I attend in SF? Would you be interested? I think you'd be awesome.
Let me know if you'd like me to do introductions.
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The Limitless Potential of a Slap to the Face: ph33r m3!!1!
2008-06-25 22:09 (UTC)
(no subject)
picture_keywordph33r m3!!1!
Great articles -- thanks very much for the links.

As for your own thoughts presented here, they raise one obvious question for me: what makes the "recursive answer" unsatisfying, anyway? Is it just that it doesn't give us one initial link in the causal chain? It seems to me that might be a bit like complaining that evolution doesn't explain what the very first living entity on Earth was and how it came about, only worse; it is probably more reasonable, after all, to posit only one original living entity than it is to posit one original social force.
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2008-06-26 00:49 (UTC)
(no subject)
I'm not going to delve into the specifics of the many things you've touched on here, but I do have a general observation. Whenever someone believes, or a study seems to indicate, that a particular phenomenon doesn't have a genetic component, I wonder why not? If the trait is such that it should differentially confer advantages in different environments, and the populations involved did exist in different environments for an evolutionarily significant length of time, then we should expect to find a genetic difference— otherwise, what was natural selection up to all that time?

Of course, this reasoning applies in the case of racial differences but not gender differences, as males and females obviously aren't reproductively isolated from one another! The evolution of sexual dimorphism is therefore quite different from, say, Swedes evolving to be different from Nigerians. I think this means one has to be very cautious when drawing parallels between the two kinds of differences. The environmental/social components may work similarly, but any genetic component (if there is one) will have explanations in the two cases.
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