Mental Age

In psychology, mental age is the age corresponding to the degree of intellectual development. It is measured by several psychological tests.

The first intelligence test developed in 1905 by Alfred Bine allows to compare the values of a child with those of groups of children of different ages. Binet had the idea to name the result of this comparison, the mental age of the child.

It indicates that a child of a certain chronological age (difference between the test date and his birth date) receives a score equal to the average of a group of children of an age that can be identical, younger or older. For example, an 8-year-old child may receive intelligence test results equal to the average for 7-year-olds : his mental age is then said to be 7 years.

Statistical properties and measurement

Psychologist William Stern had the idea of generating a quotient from mental age and chronological age that shows the difference between the two scores: the intelligence quotient or IQ. It is obtained by dividing mental age by chronological age and multiplying the result by 100.

For example, a 10-year-old child of chronological age (indicated by date of birth) with a mental age of 12 gets an IQ of 120 ((12/10) ⅹ 100). According to this method, an average IQ is 100: mental age is equal to chronological age.

This method had methodological and statistical problems. The IQs of subsequent tests developed by David Wechsler , do not take up the concept of mental age and calculate IQ differently by comparing each child with a group of children of the same chronological age.

Thus, two ways of calculating IQ are possible. IQ calculated using mental age is sometimes referred to as "classical IQ" or "mental age IQ." IQ calculated using the Wechsler approach is sometimes referred to as "standard IQ" (the child's score is compared to the score of children of the same age scaled on a normal curve, or to the Gaussian curve whose mean is 100 points and standard deviation is 15 points ).

iq and age

Controversy

Mental age is a controversial concept and is particularly indicative of young children and people with intellectual disabilities.

The results of a test indicating a mental age (or mental age IQ) have no diagnostic value. These results are integrated with other observations as part of the psychological examination conducted by a psychologist .

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