## Concept of Mental Age (M.A.) and Intelligence Quotient (I.Q.)

### Mental Age:

In categorizing children of different abilities Binet developed a scale of units he called mental age. A Child’s intelligence was determined by the mental age level which he could attain on the test. A ten years old child who was able to all the tests meant for ten years old children was said to be normal or average. If he could do the test meant for a higher age level his mental age was said to be more than his chronological age and he was described as a bright child. If he was unable to do the tests meant for his own age level, the child’s “mental age” was said to be lower than his chronological age and he was described as slow or retarded. Mental age is a simple and useful concept. You can easily interpret it, when deal with children differing in metal ability.

### Chronological Age: (C. A.)

Chronological age is nothing but the actual calendar age of the child. The real age of the child in mental into consideration for test is called chronological age.

### Intelligent Quotient ( I.Q.):

The intelligent quotient represents the degree of brightness possessed by an individual. It expresses intelligent as the ratio of the metal age of the chronological age. When the mental age is divided by the chronological age and the quotient is multiplied by 100 the result is I. Q. So the formula of finding out I. Q is.

I.Q =
Or I.Q =
The fraction is multiplied by 100 in order to remove the decimal point and to give the I. Q. a value of 100 when mental age is equal with chronological age. This if the M. A. is above the C. A.

I. Q. will be above 100. If the M. A. is less than the C. A. the resulting I. Q. will be less than 100. thus the scale has the same meaning from one age to another. I. Q, may also be regarded as an index of brightness. The following table shows the relationship between I.Q. and the degree of brightness given by Dr. Merrily based on the studies by Terman Merely Revision.

 I. Q. Range Classification Percentage of populations 140 and above Very superior 1.5 129 -139 Superior 11 110 – 119 High - Average 18 90 – 109 Average 47 80 – 89 Low Average 14 70 – 79 Borderline defective 6 Below 70 Mentally defective 2.5

The lowest classification mentally defective sometimes subdivided into three classes as:
Moron           I.Q. – 50 – 70
Imbecility      I. Q. – 20 – 50
Idiot              I. Q. – Below 20

Thus you can use the intelligence tests already developed or you can  also  prepare  an  intelligence tests  of  measure  the intelligence of an individual.

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