7.3 Intelligence Quotient
Intelligence Quotient:- It was in 1908 that Binet and Simon introduced the concept of mental age, as something distinct from chronological age. As Sorenson has pointed out, “Mental Age (M.A.) is determined by use of mental or intelligence tests. The average score for children of any chronological age indicated level or levels of mental development.”
In simple terms, mental age can be determined in the following manner. If a child age eight years can solve the questions in an intelligence test intended for ten-year old children, then his mental age be taken to be ten.
However, there were obvious possibilities of errors in the calculation of mental age. Hence, psychologists proposed the concept of Intelligence Quotient. The formula for finding out intelligence quotient the following :
If it is assumed that a child’s chronological age is 12 years, and if it is further assumed that he can take intelligence test meant for 15 year old child, then, according to the formulas, his IQ will be calculated thus :
The intelligence quotient throws light upon the mutual correlation between mental age and chronologcial age, and hence, it indicates the rate of progress of the individual. It should be noted that a child’s I.Q. does not remain the same throughout his life, because mental age develops as the individual’s chronological age increases.
Terman and Merill conducted tests on 3184 students and classified I.Q. in the following manner:-
Terman - Merit test result of I.O.
I.Q. Span Description Percentage
Above140 Genius 0.5
130-139 Very Superior 3.0
120-129 Superior 7.0
110-119 Bright 14.0
100-109 High Normal 25.0
90-99 Low Normal 25.0
80-89 Dull 14.0
70-79 Inferior 7.0
60-69 Feebel - minded 0.5
I.Q. Span Description Percentage
Above140 Genius 0.5
130-139 Very Superior 3.0
120-129 Superior 7.0
110-119 Bright 14.0
100-109 High Normal 25.0
90-99 Low Normal 25.0
80-89 Dull 14.0
70-79 Inferior 7.0
60-69 Feebel - minded 0.5
