The Bell Curve wars, 18 years on

I’ll comment on this latter. For now, I’ll borrow JL’s pithy review:

“They frame the paper as an update of the 1996 APA report, but I don’t think it can be characterized as one. That’s because the authors of the 1996 report were a relatively balanced combination of hereditarians and environmentalists, whereas this new paper was written by people who are all firmly in the environmentalist camp. All of the authors are well-known for advancing some strong environmentalist positions, and the paper gives lots of space to their pet theories and interpretations — for example, Aronson and stereotype threat, Halpern and sex differences, Turkheimer and SES-heritability interaction, Dickens & Flynn and G-E correlation, Nisbett and environmental interventions etc.”

Nisbett, Aronson, Blair, Dickens, Flynn, Halpern, and Turkheimer.
(2012, January 2). Intelligence: New Findings and Theoretical Developments. American
Psychologist. Advance online publication. doi: 10.1037/a0026699

We review new findings and new theoretical developments in the field of intelligence. New findings include the following: (a) Heritability of IQ varies significantly by social class. (b) Almost no genetic polymorphisms have been discovered that are consistently associated with variation in IQ in the normal range. (c) Much has been learned about the biological underpinnings of intelligence. (d) “Crystallized” and “fluid” IQ are quite different aspects of intelligence at both the behavioral and biological levels. (e) The importance of the environment for IQ is established by the 12-point to 18-point increase in IQ when children are adopted from working-class to middle-class homes. (f) Even when improvements in IQ produced by the most effective early childhood interventions fail to persist, there can be very marked effects on academic achievement and life outcomes. (g) In most developed countries studied, gains on IQ tests have continued, and they are beginning in the developing world. (h) Sex differences in aspects of intelligence are due partly to identifiable biological factors and partly to socialization factors. (i) The IQ gap between Blacks and Whites has been reduced by 0.33 SD in recent years. We report theorizing concerning (a) the relationship between working memory and intelligence, (b) the apparent contradiction between strong heritability effects on IQ and strong secular effects on IQ, (c) whether a general intelligence factor could arise from initially largely independent cognitive skills, (d) the relation between self-regulation and cognitive skills, and (e) the effects of stress on intelligence.

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7 Responses to The Bell Curve wars, 18 years on

  1. Kiwiguy says:

    Before even reading the abstract that appears to be a whos who of prominent environmentalists 🙂 I will look forward to reading it and seeing if Gottfredson, Murray, Rushton & co have any response.

  2. Kiwiguy says:

    edit: who’s who.

    Also, Happy New Year 🙂

  3. Kiwiguy says:

    Just looking at the section on asian – w group differences they attribute these to selective immigration and culture. No mention of adoption studies as discussed here.

    http://www.gnxp.com/MT2/archives/004064.html

  4. JL says:

    They frame the paper as an update of the 1996 APA report, but I don’t think it can be characterized as one. That’s because the authors of the 1996 report were a relatively balanced combination of hereditarians and environmentalists, whereas this new paper was written by people who are all firmly in the environmentalist camp. All of the authors are well-known for advancing some strong environmentalist positions, and the paper gives lots of space to their pet theories and interpretations — for example, Aronson and stereotype threat, Halpern and sex differences, Turkheimer and SES-heritability interaction, Dickens & Flynn and G-E correlation, Nisbett and environmental interventions etc.

    The race section is pretty short and weak. It’s a retread of Nisbett and Flynn’s views. Elsie Moore’s study gets prominently discussed as does Eyferth. Scarr’s transracial adoption study is dismissed as flawed and useless in a footnote, whereas the problems of e.g. the Eyferth study are not mentioned at all. They say that the b-w gap has narrowed, but then assert that it is 17 points among 24-year-olds.

    The new molecular genetic methods of Visscher et al. are not discussed.

    I’d love to see Murray do an update on The Bell Curve. Perhaps a book called “The Bell Curve After 20 Years” in 2014? The longitudinal NLSY data has kept accumulating, and I think many of the associations reported in 1994 have grown stronger over years (for example, income becomes more strongly correlated with IQ with age).

  5. Meng Hu says:

    On top of what JL has already said, the secular increase does not occur on g, and there are reasons to believe that children today mature sooner.

    “Today’s children score higher, not because their real intelligence has increased, but because their brains are more mature. A 10 year old today has a brain that has grown faster and has more neural connections than the brain of a 10 year old who lived, say, 50 years ago. Because today’s 10 year olds have brains that, perhaps, 12 year olds had 50 years ago, they do better on an IQ test taken by 10 year olds 50 years ago. Psychologists think they are comparing identical groups of children – 10 year olds to 10 year olds, but they are actually comparing apples and oranges – 10 year old brains to 12 year old brains. Real intelligence has not increased, children just acquire it sooner, and fully mature people today may actually be less intelligent than fully mature people were decades ago.”

    http://majorityrights.com/weblog/comments/a_possible_explanation_for_the_flynn_effect/

  6. Rastus says:

    I am curious as to whether the study participants characterized as “black” in more recent studies are apples-to-apples with those characterized as “black” in older studies. That is, would Obama be characterized as “black”? Increasingly–my extended family being one example–inter-racial couples are having babies that usually get characterized as black, but that have genes to which a white mother or father contributed. This was not true nearly as often ten, or twenty or fifty years ago, and I have no idea whether it affects the validity of comparisons between races. But, it seems like it could explain at least a portion of the closure in the gap.

    • Chuck says:

      So there are two issues: Mixed race marriages and immigration. On average, Black immigrants score well above “native Blacks” (but seem to score below native Whites). And on average Mixed race kids score somewhere in between their parental populations (at least in the case of Blacks and Whites.) At least 10% of “Black” kids (under the age of 10) are now of mixed unions and at least 10% are 2nd Gen Blacks. So that should have some impact. But the results above are from the workforce and the average working age is about 40. The the effects of immigration and admixture would not likely have trickled up enough to effect those scores.

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