January 4, 2012

Intelligence: New findings and theoretical developments

Intelligence: New findings and theoretical developments

By Richard Nisbett, Joshua Aronson, Clancy Blair, William Dickens, James Flynn, Diane Halpern, and Eric Turkheimer

American Psychologist, Jan 2 , 2012

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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  1. You report the following: "The IQ gap between Blacks and Whites has been reduced by 0.33 SD in recent years."

    I am curious about whether the "blacks" studied recently are apples-to-apples with the "blacks" in earlier studies. I.e., I have seen evidence that children of interracial couples have IQs that are higher, on average, than children of two black parents. And, increasingly, many people (e.g., Obama) are of mixed-racial lineage. DO you know whether the blacks being studied currently are less "black" than the ones to whom you are comparing them? Thanks

  2. Thanks Anonymous,

    First of all, I don't know the answer to your question. haven't been able to get a copy of the article itself, yet. (If someone can get me a pdf, that would be nice). It may be true what you are suspecting.

    Related to this topic is the following issue. I don't like talking about people in terms of 'black' and 'white' at all. Actually, I think it is nonsense to do so and I think it is a shame that is has become such a common habit to do so. I think people are never black nor white in the first place. (Brown colored people, yes, but black?). I am very skeptical about the biological existence of race and think that what we think of as biological races are socially constructed, cultural categories (for more on this see http://amzn.to/y9P1aT).

    I am convinced that this 'racial gap' is more than anything else a cultural gap which can be bridged fully.

    I agree with what Neil deGrasse Tyson says about this topic: ""I’m intrigued though, because Obama is exactly half white. Yet no one says he’s white. They say he’s black. And so you say he’s black because that’s how you treat him. That’s how you categorize him. But I look forward to the day when we look back at this time and saying that he’s black or saying that he’s anything, we just laugh at it. Because he’s as white as he is black but no one says he’s white. That’s kind of curious. Why don’t you say he’s white?" (for more see http://bit.ly/8YVgb2).

    * Disclosure: my wife is brown skinned and my two kids have light brown skins.

  3. Hi Anonymous, I've now read the article and here is a quote which confirms your hypothesis:

    "Nisbett (2009) maintains that there is actually a substantial amount of direct evidence stemming from the fact that the “Black” gene pool in the United States contains a large amount of European genes."

    This does, however, not mean that this fact explains the rise in "black" IQ's:

    "He maintains that almost all the research indicates no higher IQs for Blacks with a significant degree of European heritage than for those with much less."

  4. Still a bit more information on this:

    "Moore (1986) [...] examined the IQs of Black and mixedrace children averaging 81⁄2 years of age who were adopted by middle-class families who were either Black or White. The children who were of half-European origin had virtually the same average IQ as the children who were of exclusively Black origin. Hence European genes were of no advantage to this group of “Blacks.” Children (both Black and mixed-race) adopted by White families had IQs 13 points higher on average than those adopted by Black families, indicating that there were marked differences in
    the environments of Black and White families relevant to socialization for IQ; indeed, the differences were large enough to account for virtually the entire Black–White gap in IQ at the time of the study."

  5. Thank you for your informative website and opening this debate with a current research paper.

    This whole domain of inquiry became so toxic in the late 1990's. It is good to see that at last we are progressing beyond the nature/nurture split moving to a more nuanced approach using some of the constructs of complexity theory.


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