Sunday, June 12, 2005

Race, IQ and genetics - back on the scholarly radar screen

“Throughout the history of psychology, no question has been so persistent or so resistant to resolution as that of the relative roles of nature and nurture in causing individual and group differences in cognitive ability (Degler, 1991; Loehlin, Lindzey, & Spuhler, 1975)” (Rushton & Jensen, 2005)

To say the least, the above is no understatement.

Probably no contemporary research article has stirred such contentious debate as did Arthur Jensen’s 1969 article in the Harvard Educational Review titled “How Much Can We Boost IQ and School Achievement?” In this historical and controversial article, Jensen concluded that (Rushton & Jensen, 2005):
  • IQ tests measure socially relevant general ability
  • Individual differences in IQ have a high heritability, at least for the White populations of the United States and Europe
  • Compensatory educational programs have proved generally ineffective in raising the IQs or school achievement of individuals or groups
  • Because social mobility is linked to ability, social class differences in IQ probably have an appreciable genetic component; and tentatively, but most controversially
  • The mean Black–White group difference in IQ probably has some genetic component.

Any psychologist who has treaded on the topic of race, genetics and intelligence has found it a literal mind field

The most recent skirmish regarding this controversial topic was sparked by Herrnstein and Murray’s (1994) The Bell Curve. The Bell Curve generated countless journal articles and books, including an article generated by a special 11-person Task Force (Neisser et al., 1996) of the American Psychological Association (APA).

Fast forward to today.

The APA journal Psychology, Public Policy and Law has again revisited the race/IQ/genetics issue in a series of articles anchored in a lead article by Rushton and Jensen. The lead article is followed by a series of responses by major players in the field. Listed below are the titles and abstracts of the articles in this special issue.

Let me set one thing straight. As the dictator of this blog, I’m only presenting this information on an FYI basis. I do not endorse, either implicitly or explicitly, the position of any of the proponents in this debate. I have not studied the research literature and/or related publications (which are extensive) to the point where I feel I can render any reasonable judgment regarding this contentious topic. I am at the novice end of the race/IQ/genetics research and theory novice/expert continuum. The purpose of this post is to alert serious students and scholars in the field of applied intelligence testing of a publicaton that will likely become a frequently cited source regarding the contentious topic of race, intelligence and genetics.

I will only offer but one opinion.

Regardless of one’s conclusions/beliefs regarding this issue, I found the lead Rushton and Jensen article to be the most succinct, lucid and well-organized synthesis of the historical and contemporary research in this domain. The framework provided by Rushton and Jensen is an excellent organizational heuristic for integrating the vast literature in this domain. The organizational framework provided by Rushton and Jensen is worth the reading……regardless of one’s degree of agreement with their research and conclusions.

I recommend that faculty members who cover the IQ/race/genetics topic in their intelligence theory and/or assessment courses use this special journal issue as a core reading. I would also recommend that all scholars and applied practitioners, who study and/or engage in applied intelligence testing, seriously consider purchasing a copy of this journal issue for reading and reference.

Below are the respective articles and abstracts.

Rushton, J. P., & Jensen, A. R. (2005). Thirty years of research on race differences in cognitive ability. Psychology Public Policy and Law, 11(2), 235-294.

  • The culture-only (0% genetic–100% environmental) and the hereditarian (50% genetic–50% environmental) models of the causes of mean Black–White differences in cognitive ability are compared and contrasted across 10 categories of evidence: the worldwide distribution of test scores, g factor of mental ability, heritability, brain size and cognitive ability, transracial adoption, racial admixture, regression, related life-history traits, human origins research, and hypothesized environmental variables. The new evidence reviewed here points to some genetic component in Black–White differences in mean IQ. The implication for public policy is that the discrimination model (i.e., Black–White differences in socially valued outcomes will be equal barring discrimination) must be tempered by a distributional model (i.e., Black–White outcomes reflect underlying group characteristics).

Sternberg, R. J. (2005). There are no public-policy implications - A reply to Rushton and Jensen (2005). Psychology Public Policy and Law, 11(2), 295-301.

  • J. P. Rushton and A. R. Jensen (2005) purport to show public-policy implications arising from their analysis of alleged genetic bases for group mean differences in IQ. This article argues that none of these implications in fact follow from any of the data they present. The risk in work such as this is that public-policy implications may come to be ideologically driven rather than data driven, and to drive the research rather than be driven by the

Nisbett, R. E. (2005). Heredity, environment, and race differences in IQ - A commentary on Rushton and Jensen (2005). Psychology Public Policy and Law, 11(2), 302-310.

  • J. P. Rushton and A. R. Jensen (2005) ignore or misinterpret most of the evidence of greatest relevance to the question of heritability of the Black–White IQ gap. A dispassionate reading of the evidence on the association of IQ with degree of European ancestry for members of Black populations, convergence of Black and White IQ in recent years, alterability of Black IQ by intervention programs, and adoption studies lend no support to a hereditarian interpretation of the Black–White IQ gap. On the contrary, the evidence most relevant to the question indicates that the genetic contribution to the Black–White IQ gap is nil.

Suzuki, L., & Aronson, J. (2005). The cultural malleability of intelligence and its impact on the racial/ethnic hierarchy. Psychology Public Policy and Law, 11(2), 320-327.

  • This commentary highlights previous literature focusing on cultural and environmental explanations for the racial/ethnic group hierarchy of intelligence. Assumptions underlying definitions of intelligence, heritability/genetics, culture, and race are noted. Historical, contextual, and testing issues are clarified. Specific attention is given to studies supporting stereotype threat, effects of mediated learning experiences, and relative functionalism. Current test development practices are critiqued with respect to methods of validation and item development. Implications of the genetic vs. culture-only arguments are discussed with respect to the malleability of IQ.

Gottfredson, L. S. (2005). What if the hereditarian hypothesis is true? Psychology Public Policy and Law, 11(2), 311-319.

  • J. P. Rushton and A. R. Jensen (2005) review 10 bodies of evidence to support their argument that the long-standing, worldwide Black–White average differences in cognitive ability are more plausibly explained by their hereditarian (50% genetic causation) theory than by culture-only (0% genetic causation) theory. This commentary evaluates the relevance of their evidence, the overall strength of their case, the implications they draw for public policy, and the suggestion by some scholars that the nation is best served by telling benevolent lies about race and intelligence.

Rushton, J. P., & Jensen, A. R. (2005). Wanted: More race realism, less moralistic fallacy. Psychology Public Policy and Law, 11(2), 328-336.

  • Despite repeated claims to the contrary, there has been no narrowing of the 15- to 18-point average IQ difference between Blacks and Whites (1.1 standard deviations); the differences are as large today as they were when first measured nearly 100 years ago. They, and the concomitant difference in standard of living, level of education, and related phenomena, lie in factors that are largely heritable, not cultural. The IQ differences are attributable to differences in brain size more than to racism, stereotype threat, item selection on tests, and all the other suggestions given by the commentators. It is time to meet reality. It is time to stop committing the “moralistic fallacy” that good science must conform to approved outcomes.


Anonymous said...


Dr. Rushton has put the full articles (*odf) on his web site:

Anonymous said...

Haven't nonverbal IQ tests like the UNIT consigned this antiquated statistical fallacy to a cobwebbed corner in a KKK den? Jensen and Rushton have not picked up testing manuals for the Wechsler Scales since they ascended to the bully pulpit; the B/W gap is quickly narrowing. Bet on this: statistical insignifcance will emerge in the next versions.

Bruce Lewin said...

Hi Kevin,

This certainly is a mine field!!!

Marian said...

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