This page contains a Flash digital edition of a book.
Psychology, Public Policy, and Law Copyright 2005 by the American Psychological Association
2005, Vol. 11, No. 2, 235–294 1076-8971/05/$12.00 DOI: 10.1037/1076-8971.11.2.235
THIRTY YEARS OF RESEARCH ON RACE
DIFFERENCES IN COGNITIVE ABILITY
J. Philippe Rushton Arthur R. Jensen
The University of Western Ontario University of California, Berkeley
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 vari-
ables. 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).
Section 1: Background
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). The scientific debate goes back to the
mid-19th century (e.g., Galton, 1869; Nott & Glidden, 1854). Starting with the
widespread use of standardized mental tests in World War I, average ethnic and
racial group differences were found. Especially vexing has been the cause(s) of
the 15-point Black–White IQ difference in the United States.
In 1969, the Harvard Educational Review published Arthur Jensen’s lengthy
article, “How Much Can We Boost IQ and School Achievement?” Jensen con-
cluded that (a) IQ tests measure socially relevant general ability; (b) individual
differences in IQ have a high heritability, at least for the White populations of the
United States and Europe; (c) compensatory educational programs have proved
generally ineffective in raising the IQs or school achievement of individuals or
groups; (d) because social mobility is linked to ability, social class differences in
IQ probably have an appreciable genetic component; and tentatively, but most
controversially, (e) the mean Black–White group difference in IQ probably has
some genetic component.
Jensen’s (1969) article was covered in Time, Newsweek, Life, U.S. News &
World Report, and New York Times Magazine. His conclusions, the theoretical
issues they raised, and the public policy recommendations that many saw as
stemming directly from them were dubbed “Jensenism,” a term which entered the
J. Philippe Rushton, Department of Psychology, The University of Western Ontario, London,
Ontario, Canada; Arthur R. Jensen, School of Education, University of California, Berkeley.
Correspondence concerning this article should be addressed to J. Philippe Rushton, Department
of Psychology, The University of Western Ontario, London, Ontario N6A 5C2, Canada. E-mail:
rushton@uwo.ca
235
Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60
Produced with Yudu - www.yudu.com