Race and IQ: A Theory-Based Review of the Research in Richard Nisbett ’ s Intelligence and How to Get It

Abstract

We provide a detailed review of data from psychology, genetics, and neuroscience in a point-counterpoint format to enable readers to identify the merits and demerits of each side of the debate over whether the culture-only (0% genetic-100% environmental) or nature + nurture model (50% genetic-50% environmental) best explains mean ethnic group differences in intelligence test scores: Jewish (mean IQ = 113), East Asian (106), White (100), Hispanic (90), South Asian (87), African American (85), and sub-Saharan African (70). We juxtapose Richard Nisbett's position, expressed in his book Intelligence and How to Get It, with our own, to examine his thesis that cultural factors alone are sufficient to explain the differences and that the nature + nurture model we have presented over the last 40 years is unnecessary. We review the evidence in 14 topics of contention: (1) data to be explained; (2) malleability of IQ test scores; (3) cultureloaded versus g-loaded tests; (4) stereotype threat, caste, and "X" factors; (5) reaction-time measures; (6) within-race heritability; (7) between-race heritability; (8) sub-Saharan African IQ scores; (9) race differences in brain size; (10) sex differences in brain size; (11) trans-racial adoption studies; (12) racial admixture studies; (13) regression to the mean effects; and (14) human origins research and life-history traits. We conclude that the preponderance of evidence demonstrates that in intelligence, brain size, and other life history traits, East Asians average higher than do Europeans who average higher do South Asians, African Americans, or sub-Saharan Africans. The group differences are between 50 and 80% heritable.Nisbett: James Flynn discovered that in the developed world as a whole, IQ scores increased markedly over the last 50 years. This suggests that the 15-point IQ difference between Blacks and Whites will gradually disappear over time. Indeed, Black IQ today is superior to White IQ in 1950! Dickens and Flynn [24] showed the Black-White IQ gap narrowed by 5.5 points between 1972 and 2002. They documented a drop from 15 to 9.5 points on a combination of the Wechsler Intelligence Scale for Children (WISC), the Wechsler Adult Intelligence Scale (WAIS), the Stanford-Binet, and the Armed Forces Qualification Test (AFQT). It is hard to overestimate the importance of a gap reduction of this magnitude. It reduces the ratio of Whites to Blacks with an IQ of 130 (the level needed to be a highly successful professional) from 18 to 1 to only 6 to 1. Even including the several additional tests that Rushton and Jensen [25] said were wrongly omitted, the median Black IQ gain is still 4.5 points, which is not very different from the 5.5 point estimate given by Dickens and Flynn.The Black-White difference shrank comparably on the National Assessment of Educational Progress (NAEP) Long-Term Trend tests. These have been given every few years since the early 1970s by the U.S. Department of Education to a random sample of 9-, 13-, and 17-year-olds. For children born as early as 1954,...

The rise and fall of the Flynn Effect as a reason to expect a narrowing of the Black–White IQ gap☆

“…Subsequently, Wicherts and Johnson (2009) criticized this study for using "unreliable" item-level analyses, even though the items found relatively difficult (or easy) by twins in North America were the ones found relatively difficult (or easy) by the Roma in Serbia, and by Whites, South Asians, Coloreds, and Blacks in South Africa (mean r = 0.87). However, Rushton and Jensen (2010) corroborated the results after organizing the items into more reliable parcels, each containing six or more items. As the heritability of the parcels increased, so did the mean group differences (mean r = 0.74; P b 0.01).…”

“…In a technical Appendix, "The Case for a Purely Environmental Basis for Black/White Differences in IQ," the author critiques our position (the default hypothesis of behavior genetics) that both individual and group differences are the result of both nature and nurture (Jensen, 1969(Jensen, , 1973(Jensen, , 1998Rushton, 1995, Rushton & Jensen, 2005, along with many conclusions from The Bell Curve (Herrnstein & Murray, 1994). We have replied to the arguments in Nisbett's book in detail (Rushton & Jensen, 2010).…”

The mean Southern Italian children IQ is not particularly low: A reply to R. Lynn (2010)

“…Despite the fact that it may be open to criticisms (for a debate see Rushton and Jensen, 2010;Wicherts and Johnson, 2009) the method can offer further information useful in the present context. With our present data set, it was possible to run analyses at this level only for the case of the 310 North Italy and 313 South Italy 10 th -graders tested with the reading comprehension test (20 items).…”

Future Efforts in Flynn Effect Research: Balancing Reductionism with Holism

“…As such, boosting these traits in poor countries should be relatively easy. To date, results of intervention efforts have been mixed at best, and nowhere close to 19 cm in height or 20 IQ points [56], ([65] and its critique in [66]), [67,68]. The ability to intervene so as to speed up IQ gains, in genetically informed studies such as those using siblings as controls, should be considered the ultimate test of any environmental hypothesis for the Flynn effect.…”