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Mental Age

Mental age refers to an age-normed level of performance on an intelligence test, and it became a popular way of referring to "mental level" as measured by the Binet-Simon Scale of 1908. The Binet-Simon Scale identified the academic skills typical of specific age groups. In 1912 William Stern used chronological age as a denominator to be divided into mental age, resulting in an intelligence quotient. In 1916 Lewis Terman multiplied this intelligence quotient by 100 (to eliminate the decimal places) and called the result an IQ score. Terman's formula of mental age divided by chronological age multiplied by 100 became popularized as the formula for calculating a person's IQ. Adult intelligence does not change from year to year so the concept of mental age is less meaningful when discussing adults. Contemporary IQ tests use cumulative indexes to determine scores rather than the calculation of IQ scores based upon Terman's formula. A contemporary equivalent of mental age is the Standard Age Score of the Stanford-Binet IQ test, which was formulated in 1987.


Anastasi, Anne. Psychological Testing. New York: Macmillan, 1988.

Fancher, Raymond. Pioneers of Psychology. New York: Norton, 1990.

Francine Smolucha

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