The existence of a link between race and intelligence has been repeatedly observed by scientists, but remains extremely controversial. Research suggests that the average IQ score of East Asians is higher than that of Europeans, and the average IQ score of Europeans is higher than that of Africans and African-Americans. Additional research has indicated that environmental factors such as socio-economic status and education can explain some, but not all, of these observed differences in IQ.
1910s
In 1917, tests developed by Robert Yerkes were used to evaluate American draftees. Researchers found that: Southern and Eastern European immigrants scored lower than Americans (who at the time were largely Western and Northern Europeans); Americans from northern states had higher scores than Americans from southern states; and Black Americans scored lower than White Americans.[1] However, some scientists argued that immigrants performed poorly on these tests because English was not their first language.[2]
1930s
Psychologist Carl Brigham and anthropologists Franz Boas, and Ruth Benedict and Gene Weltfish argued that environmental factors, not genetic ones, explained differences in IQ scores.
Desegregation
In 1958, Audrey Shuey published The Testing of Negro Intelligence, in which she attempted to demonstrate that the difference between the average IQ scores of blacks and whites had not changed since IQ was first measured. In the 1960s, Nobel laureate William Shockley, argued that black children were innately unable to learn as well as white children.[3] Arthur Jensen, in a Harvard Education Review article entitled “How Much Can We Boost IQ and Scholastic Achievement?”[4][5][6][7] questioned the value of remedial education for African-American children. Jensen argued that their poor educational performance was genetic.[8] He continued research into the question until his death in 2012.
1990s
The Bell Curve (1994), written by Richard Herrnstein and Charles Murray, emphasized the societal effects of low IQ.[9]. Fifty-two researchers (mostly psychologists) signed an editorial statement “Mainstream Science on Intelligence” which was generally supportive of the claims of The Bell Curve.
In 1995 report from the American Psychological Association, “Intelligence: Knowns and Unknowns”, noted that racial differences in IQ scores existed, and concluded that no current theories adequately explained it.
Several books were written in criticism of The Bell Curve, including: The Bell Curve Debate (1995), Inequality by Design: Cracking the Bell Curve Myth (1996) and a second edition of The Mismeasure of Man (1996) by Stephen Jay Gould.[10]
2000s
A review article “Thirty Years of Research on Race Differences in Cognitive Ability” by J. Philippe Rushton and Arthur Jensen was published in 2005.[11] The article was followed by a series of responses, some in support, some critical.[12][13] Richard Nisbett, another psychologist who had also commented at the time, later included an amplified version of his critique as part of the book Intelligence and How to Get It: Why Schools and Cultures Count (2009).[14] Rushton and Jensen in 2010 made a point-by-point reply to this thereafter.[15] A comprehensive review article on the issue was published in the journal American Psychologist in 2012.[16]
Rushton & Jensen (2005) wrote that, in the United States, self-identified blacks and whites have been the subjects of the greatest number of studies. They stated that the black-white IQ difference is about 15 to 18 points or 1 to 1.1 standard deviations (SDs), which implies that between 11 and 16 percent of the black population have an IQ above 100 (the general population median). According to Arthur Jensen and J. Philippe Rushton the black-white IQ difference is largest on those components of IQ tests that best measure the general intelligence factor g.[17] The 1996 APA report “Intelligence: Knowns and Unknowns” and the 1994 editorial statement “Mainstream Science on Intelligence” gave more or less similar estimates.[18][19]
Roth et al. (2001), in a review of the results of a total of 6,246,729 participants on other tests of cognitive ability or aptitude, found a difference in mean IQ scores between blacks and whites of 1.1 SD. Consistent results were found for college and university application tests such as the Scholastic Aptitude Test (N = 2.4 million) and Graduate Record Examination (N = 2.3 million), as well as for tests of job applicants in corporate sections (N = 0.5 million) and in the military (N = 0.4 million).[20] North East Asians have tended to score relatively higher on visuospatial subtests with lower scores in verbal subtests while Ashkenazi Jews score higher in verbal and reasoning subtests with lower scores in visuospatial subtests. The few Amerindian populations who have been systematically tested, including Arctic Natives, tend to score worse on average than white populations but better on average than black populations.[20]
A 2006 study by Dickens and Flynn estimated that the difference between mean scores of blacks and whites closed by about 5 or 6 IQ points between 1972 and 2002,[21] which would be a reduction of about one-third. In the same period the educational achievement disparity also diminished.[22] However, this was challenged by Rushton & Jensen who said the difference had remained stable.[23] In a 2006 study, Murray agreed with Dickens and Flynn that there has been a narrowing of the difference, but stated that the difference was not continuing to decrease.[24]
Some studies reviewed by Hunt (2010), p. 418 found that rise in the average achievement of African Americans was caused by a reduction in the number of African American students in the lowest range of scores without a corresponding increase in the number of students in the highest ranges. A 2012 review of the literature found that the IQ gap had diminished by 0.33 standard deviations since first reported.[16]
