A Science Odyssey
People and Discoveries
Alfred Binet Binet pioneers intelligence testing

French psychologist Alfred Binet (1859-1911) took a different tack than most psychologists of his day: he was interested in the workings of the normal mind rather than the pathology of mental illness. He wanted to find a way to measure the ability to think and reason, apart from education in any particular field.

In 1905 he developed a test in which he had children do tasks such as follow commands, copy patterns, name objects, and put things in order or arrange them properly. He gave the test to Paris schoolchildren and created a standard based on his data. For example, if 70 percent of 8-year-olds could pass a particular test, then success on the test represented the 8-year-old level of intelligence. From Binet's work, the phrase "intelligence quotient," or "IQ," entered the vocabulary. The IQ is the ratio of "mental age" to chronological age, with 100 being average. So, an 8 year old who passes the 10 year-old's test would have an IQ of 10/8 x 100, or 125.

Binet's work set off a passion for testing and in the enthusiasm, a widespread application of tests and scoring measures developed from relatively limited data. Tests based on Binet's test were used by the U.S. Army in sorting out the vast numbers of recruits in World War I. The questions, however, had much more to do with general knowledge than with mental tasks such as sequencing or matching. The results, released after the war, showed that the majority of recruits had a juvenile intelligence. This shocking news played into the hands of eugenicists who argued that intelligence was an innate, inheritable trait limited to certain types (or nationalities) of people.

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