IQ

Psychol.

See intelligence quotient.

[1960-65]

* * *

in full intelligence quotient

Number intended to represent a measure of relative intelligence as determined by the subject's responses to a series of test problems.

The IQ was originally computed as the ratio of a person's mental age to his or her chronological (physical) age, multiplied by 100, but use of the concept of mental age has been largely discontinued, and IQ is now generally assessed on the basis of the statistical distribution of scores. The most widely used intelligence tests are the Stanford-Binet test (1916), for children, and the Wechsler test (1939), originally for adults but now also for children. A score above 130 is considered to reflect "giftedness," while a score below 70 is considered to reflect mental impairment or mental retardation. Intelligence tests have provoked great controversy, particularly about what kinds of mental ability constitute intelligence and whether IQ adequately represents these abilities, and about cultural and class bias in test construction and standardization procedures.

* * *

▪ psychology

 (from “intelligence quotient”), a number used to express the relative intelligence of a person. It is one of many intelligence tests (intelligence test).

      IQ was originally computed by taking the ratio of mental age to chronological (physical) age and multiplying by 100. Thus, if a 10-year-old child had a mental age of 12 (that is, performed on the test at the level of an average 12-year-old), the child was assigned an IQ of ¹²/₁₀ × 100, or 120. If the 10-year-old had a mental age of 8, the child's IQ would be ⁸/₁₀ × 100, or 80. Based on this calculation, a score of 100—where the mental age equals the chronological age—would be average. Few tests continue to involve the computation of mental ages. See also Lewis Terman (Terman, Lewis Madison); Alfred Binet (Binet, Alfred).

* * *