A scale used to correlate intelligence to the typical changes that occur as a child matures.
French psychologist and educator Alfred Binet theorized that a child who appears to have limited mental abilities is able to perform on a level characteristic of younger children; conversely, a child who appears to be gifted is able to perform on the level of older children. In 1905 Binet, in collaboration with Thèophile Simon, developed a scale on which mental age could be compared to the chronological age. Thus, a bright child's mental age is higher than his or her chronological age.
In 1916, Lewis Terman , a psychologist at Stanford University, devised an intelligence test based on Binet's work (referred to today as the Stanford-Binet Intelligence Scale) and was administered to assess American school children. Terman maintained the concept of mental age in devising his formula for calculating the intelligence quotient (IQ). The formula is IQ = mental age/chronological age multiplied by 100. Thus if the child's mental age equals her chronological age, her IQ will equal 100.
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.
See also:MILESTONES OF DEVELOPMENT
Anastasi, Anne. Psychological Testing. New York: Macmillan, 1988.
Fancher, Raymond. Pioneers of Psychology. New York: Norton, 1990.