Ratio of a person’s “mental age” to their physical age. In 1904 Alfred Binet, director of the psychology laboratory at the Universite de Sorbonne, devised a series of tests for the French government. The tests were intended to identify students who might require special attention because they were not performing well in regular classrooms. Originally Binet’s tests were arranged in order of increasing difficulty, but in 1908 he sorted them according to age level, dividing them according to the youngest age at which a child could complete the test successfully. He suggested that children who needed help could be identified by subtracting their chronological age from their tested “mental age.” In 1912, a German psychologist suggested that the identifier should be computed by dividing the mental age by the chronological age, and not by subtracting. Dividing allowed measurement of the relative difference between the two qualities, whereas subtracting did not. From this comes the term intelligence quotient, or IQ.
Binet developed his test solely as a means of identifying children who needed help in schooling. However, three scientists brought the Binet test to the United States and corrupted Binet’s original intentions to support their prejudices about society. H. H. Goddard, who believed that intelligence was passed from parent to child, interpreted the tests as a method of measuring this inborn intelligence. L. M. Terman did not recognize the effects that poverty or culture might have on test results and believed in the inferiority of non-Western races. He refined the original Binet scale and suggested that IQ tests could be used to assign people to the jobs they were best suited for. R. M. Yerkes gave the IQ tests that Terman developed to U.S. soldiers during World War I again in a form that was biased in favor of white Americans of western European origin. The U.S. Congress used the data that Yerkes compiled to pass the Immigration Restriction Act of 1924, which discriminated against poorly educated people who did not perform well on IQ tests.