Nervous System

Learning and Memory

How is IQ calculated?

IQ, or the intelligence quotient, was originally computed as the ratio of a person’s mental age to his chronological age, multiplied by 100. Following this method, a child of 10 years old who performed on the test at the level of an average 12 year old (mental age of 12), was assigned an IQ of 12/10? 100 = 120. More recently, the concept of “mental age” has fallen into disrepute and IQ is computed on the basis of the statistical percentage of people who are expected to have a certain IQ. An IQ of 100 is considered average. An IQ of 70 or below indicates mental retardation, and an IQ of 130 or above indicates gifted abilities.


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