Intelligence Testing

History of Intelligence Testing

As far back as 220 BCE, efforts were made by Chinese officials to assess the abilities and skills of potential government workers. However, the origins of contemporary individual intelligence testing are often credited to the work of the British [Page 1205]polymath Sir Francis Galton in the 1880s. Galton believed that individuals with the most acute sensory functions would demonstrate superior cognitive abilities. Therefore, in the 1880s, Galton developed and administered individual tests, or brief questions, of such things as visual perception, visual–motor speed, and auditory acuity. These measures were later found to be of limited usefulness, however, in identifying individuals with strong cognitive ability.

In 1904, at the request of the French Ministry of Public Instruction, Alfred Binet and Théophile Simon began to create a different series of tests intended to assess a child's level of cognitive functioning. These included some tests of sensory perception but focused far more on tests of cognition. Binet and Simon's questions entailed problem solving that drew on everyday information to which children from varied social and economic classes would have access. The Binet and Simon tests included varied tasks such as counting coins and copying shapes. Binet argued that a variety of tasks was necessary since intelligence was not a unidimensional capacity. Thus, he argued that intelligence could not be measured linearly, as one might measure height, and that it could not be represented by a single number. Binet and Simon's test questions were arranged in order of increasing difficulty and thus took into consideration the developmental level of the child being assessed. A child's score on the test had two components: the child's chronological age and the mental-age, which was the age-level associated with the most difficult task a child could complete correctly. Another innovation was that Binet and Simon made sure that test instructions were administered in a standardized format to maintain consistency across administrations of the test.

Binet and Simon's assessment was intended to help distinguish between students who were failing because they could not learn in ordinary classrooms (e.g., students with intellectual disabilities) and those who were not learning in ordinary classrooms due to other factors (e.g., behavioral problems). Intelligence tests continue to play this role in modern-day assessment.

Binet and Simon's intelligence tests were brought to the United States by H. H. Goddard, the research director for a training school for “feebleminded” individuals in Vineland, New Jersey.

Goddard arranged to have the tests translated and began using them to assess youngsters in the training school. He also used the translated tests to screen immigrants at Ellis Island.

In 1916, Lewis Terman published an adaption of the test developed by Binet and Simon—The Stanford Revision and Extension of the Binet-Simon Scale. Terman included a number of additional tasks, but also maintained many of the features of the original Binet-Simon scale. Terman incorporated the idea of intelligence quotient, or IQ, developed in 1912 by the German psychologist William Stern. The term referred to the ratio of the child's mental age to chronological age, with a child of average ability for his or her age achieving a score of 1.00. This score was then multiplied by 100 to eliminate the decimal. Most current intelligence tests still use 100 as the average IQ score, with a standard deviation of 15 or 16 points. During this same period, Robert Yerkes added the notion of items arranged by age placement to a “point scale.” On his test, scores were based on the number of items completed correctly for each separate assessed skill. Bonus points were also given to individuals who were able to complete the items relatively quickly or for those who provided more elaborate answers. His test was called the Yerkes Point Scale and its structure served as a model for the format that would eventually be adopted by current intelligence measures.

...