A media firestorm ensued, with most of the commentary issuing from people without the statistical and methodological background to address the core claims of the book.
The American Psychological Association created a panel of eminent researchers to write a summary of what was known about intelligence, which would presumably contradict many of these claims. The panel published the article in 1996, a thoughtful rebuttal of many of the inaccurate claims in The Bell Curve, but also a very useful summary of what some of the best researchers in the field could agree on when it came to intelligence.
Now there's an update.
A group of eminent scientists thought the time was ripe to provide the field with another status-of-the-field statement. They argue that there have been three big changes in the 15 years since the last report: (1) we know much more about the biology underlying intelligence; (2) we have a much better understanding of the impact of the environment on intelligence, and that impact is larger than was suspected; (3) we have a better understanding of how genes and the environment interact.
Some of the broad conclusions are listed below (please note that these are close paraphrases of the article's abstract).
- The extent to which genes matter to intelligence varies by social class (genetic inheritance matters more if you're wealthy, less if you're poor).
- Almost no genetic polymorphisms have been discovered that are consistently associated with variation of IQ in the normal range.
- "Crystallized" and "fluid" intelligence are different, both behaviorally and biologically.
- The importance of the environment for IQ is established by the 12 to 18 point increase in IQ observed when children are adopted from working-class to middle-class homes.
- In most developed countries studied, gains on IQ tests have continued, and they are beginning in the developing world
- Sex differences in some aspects of intelligence are due partly to biological factors and partly to socialization factors.
- The IQ gap between Blacks and Whites in the US has been reduced by 0.33 standard deviations in recent years.
Neisser, U.; Boodoo, G.; Bouchard, T. J. , J.; Boykin, A. W.; Brody, N.; Ceci, S. J.; Halpern, D. F.; Loehlin, J. C. et al (1996). Intelligence: Knowns and Unknowns. American Psychologist, 51: 77.
Nisbett, R. E., Aronson, J., Blair, C., Dickens, W., Flynn, J., Halpern, D. F., & Turkheimer, E. (2012, January 2). Intelligence: New Findings and Theoretical Developments. American Psychologist, 67, 130-159.