History of the race and intelligence controversy

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The history of the race and intelligence controversy concerns the historical development of a debate about possible explanations of group differences encountered in the study of race and intelligence. Since the beginning of IQ testing around the time of World War I, there have been observed differences between the average scores of different population groups, and there have been debates over whether this is mainly due to environmental and cultural factors, or mainly due to some as yet undiscovered genetic factor, or whether such a dichotomy between environmental and genetic factors is the appropriate framing of the debate. Today, the scientific consensus is that genetics does not explain differences in IQ test performance between racial groups.^[1][2][3]

Pseudoscientific claims of inherent differences in intelligence between races have played a central role in the history of scientific racism. In the late 19th and early 20th century, group differences in intelligence were often assumed to be racial in nature.^[4] Apart from intelligence tests, research relied on measurements such as brain size or reaction times. By the mid-1940s most psychologists had adopted the view that environmental and cultural factors predominated. In the mid-1960s, physicist William Shockley sparked controversy by claiming there might be genetic reasons that black people in the United States tended to score lower on IQ tests than white people. In 1969 the educational psychologist Arthur Jensen published a long article with the suggestion that compensatory education could have failed to that date because of genetic group differences. A similar debate among academics followed the publication in 1994 of The Bell Curve by Richard Herrnstein and Charles Murray. Their book prompted a renewal of debate on the issue and the publication of several interdisciplinary books on the issue. A 1995 report from the American Psychological Association responded to the controversy, finding no conclusive explanation for the observed differences between average IQ scores of racial groups. More recent work by James Flynn, William Dickens and Richard Nisbett has highlighted the narrowing gap between racial groups in IQ test performance, along with other corroborating evidence that environmental rather than genetic factors are the cause of these differences.^[5][6][7][8]