At the beginning of the twentieth century, French psychologist Alfred Binet devised the first test of human intelligence. The test consisted of problems of increasing difficulty that were designed to measure children’s judgment, reasoning, and comprehension. Shortly after Binet’s original work, psychologist Lewis Terman of Stanford University refined and standardized the test for American children. This test became known as the Stanford-Binet Intelligence Scale, which was first published in 1916 and revised several times after that.
Terman and his colleagues developed the idea of the IQ, or intelligence quotient. IQ is a measurement of general intelligence, a number representing the ratio of mental age (performance on the test) to actual chronological age in years. IQ has proven to be an accurate measurement of a child’s potential to achieve in school and later in professional life. The most recent version of the Stanford-Binet test is still being used today and remains one of the world’s most widely used and accurate tests of general intelligence. It has produced reliable results for individuals from age two through adulthood.
Intelligence testing has caused great excitement within the scientific community and the larger society. Many psychologists agree that intelligence testing is psychology’s greatest achievement. Intelligence testing and IQ are important scientific developments with great social utility beyond the prediction of school achievement. Intelligence tests are now available to evaluate people for specific purposes, such as military service, placement in industrial organizations, and even social companionship.