HUMAN LIFE 



is only on a par with the intelligence 

 of an average normal child of eight. In 

 addition, as the mental age indicates 

 only the general level to which the 

 intelligence of the individual has devel- 

 oped at the time the tests are applied, a 

 measure of the actual rate of mental 

 development of the subject, called the 

 "intelligence quotient," is used. This 

 intelligence quotient is the percentage 

 ratio between the mental and chronologi- 

 cal age of the subject. Repeated tests 

 of the same children at intervals of one to 

 four years have indicated that the in- 

 telligence quotient of a given child re- 

 mains practically constant between the 

 ages of ten and sixteen years. By reason 

 of its relative stability, therefore, the 

 intelligence quotient becomes a reliable 

 and useful index of intelligence. Once 

 determined, it is possible to predict by it, 

 within reasonable limits, the probable 

 level to which a given individual's in- 

 telligence will develop. From a rather 

 wide experience of these specific ratings 

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