IQ

History

The French psychologists Alfred Binet (1857–1911) and Theodore Simon (1872–1961) devised the first mental tests in 1905, with the aim of identifying schoolchildren who would benefit from special education programs to improve their performance. Binet and Simon attempted to identify an array of intellectual tasks that an average French child of a particular age could be expected to perform. Children who performed more than 2 years below their chronological age were identified as needing special help. The German psychologist Wilhelm Stern (1871–1938) proposed the idea of dividing mental age by chronological age (and multiplying by 100 to avoid decimals) to yield a measure of an individual's relative development, which he called an IQ. Today, IQ is generally determined by mapping relative results onto a normal distribution bell curve with 100 as the center value and a standard deviation of 15 points.

Mental testing was taken up enthusiastically in the United States and Britain, but in both countries it immediately became entangled with hereditarian, biological determinist, eugenicist, and racist ideas. For example, the American psychologist H. H. Goddard (1866–1957), who popularized Binet's tests in the United States, took IQs to represent innate intelligence, a single capacity that could be little changed by education. Goddard attributed most social ills, including crime, to low intelligence, which he linked to limited emotional control and immorality. Goddard advocated institutionalization of the “feeble minded” (whom he designated “morons”) to prevent them from reproducing. Goddard's contemporary, Lewis Terman (1877–1956) of Stanford University (who [Page 400]created the standardized Stanford-Binet IQ tests), made the same link between low IQs and crime, arguing that although not all criminals were mentally deficient, all those significantly below average intelligence were potential criminals. Terman also argued that social classes reflected biologically inherited differences, with members of the lower classes being innately less intelligent, and that there were significant racial differences in intelligence, with American Indians, Mexicans, and Blacks all being, on average, less intelligent than Whites.

Early IQ tests were frequently administered in highly unrigorous ways in the United States, allowing results to be significantly influenced by tester prejudices, inadequate testing conditions, and culturally biased test items. In 1913, Goddard concluded that nearly 50% of immigrants from southern and eastern Europe were “feeble minded.” The Harvard psychologist Robert Yerkes (1876–1956) conducted mass testing of army recruits during World War I and concluded that the average mental age of Whites was just 13, with Blacks a little over 10, and various southern and eastern European groups somewhere in between. Yerkes gave these results a hereditarian interpretation; they were used to justify class and racial prejudices and played a central role in justifying the 1924 Immigration Restriction Act, which severely limited immigration from southern and eastern Europe.

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