INTELLIGENCE 



3008 



INTELLIGENCE 



Examples of Tests Used. The scale con- 

 tains a great variety of tests. Memory, for 

 example, is tested by the repetition of sen- 

 tences ranging from three to twenty-six sylla- 

 bles in length, and by the repetition of digit 

 series ranging from two to seven digits each. 

 There are several tests of "time orientation," 

 including distinction between forenoon and 

 afternoon, naming the days of the week and 

 the months of the year, and giving the date. 

 Eye-hand coordination is tested by drawing 

 geometrical figures from copy; wealth of ideas, 

 by naming as many words as possible in a 

 given time; perception, by denning words and 

 by the description and interpretation of pic- 

 tures; logical association, by the detection of 

 nonsense in such statements as "I have three 

 brothers Paul, Ernest, and myself;" resource- 

 fulness, by questions asking what one ought 

 to do under given circumstances, as, for ex- 

 ample, if one's house is afire, if one is going 

 some place and misses the train, etc. There 

 are also tests of language comprehension, of 

 knowledge about common objects, of ability 

 to comprehend and use abstract ideas, and of 

 other intellectual powers. 



How the Scale is Used. In using the scale it 

 is only necessary to begin the examination 

 of the subject at a point where all the tests are 

 passed, and to continue up the scale until no 

 more successes are possible. We then com- 

 pare the subject's performance with the stand- 

 ard for normal children of the same age and 

 note the amount of retardation or advance- 

 ment. If a subject goes as far in the tests 

 as normal nine-year-old children ordinarily 

 go, we can say that he has a "mental age" of 

 nine years. If he can go only as far as the 

 average eight-year-old child we say that his 

 "mental age" is eight years. In like manner, 

 a mentally defective adult may have a "mental 

 age" of only five years, or a young genius of 

 nine years may have a "mental age" of twelve 

 or fourteen years. 



It was chiefly the utilization of age stand- 

 ards that gave the Binet-Simon method its 

 great advantage over other systems of tests. 

 The principle has come to be known as the 

 "age-grade method." 



Improvements of the Binet-Simon System. 

 As left by the authors, the scale was far from 

 perfect. It was especially unsatisfactory in the 

 upper and lower ranges, yielding mental ages 

 considerably too high at the lower end and con- 

 siderably too low at the upper end. Revisions 

 and adaptations of the scale designed to elimi- 



nate these imperfections have been made in 

 nearly all the leading countries. Thie American 

 revisions most in use are those of Goddard, 

 Kuhlmann and Terman. The last, known as 

 the Stanford Revision, is based on tests of more 

 than 2,300 subjects of all ages. Besides cor- 

 recting the location of the tests used by Binet 

 and Simon, it has increased the number of 

 tests from fifty-four to ninety and has defined 

 the procedure in such detail as to make the 

 scale serviceable to teachers, physicians and 

 others who have had little psychological train- 

 ing. 



The "Intelligence Quotient." One of the 

 most important advances has come from the 

 discovery that in the mental development of 

 a given child the mental age maintains a fairly 

 constant ratio to the actual age. It has been 

 found, for example, that the five-year-old of 

 four-year intelligence (20 per cent retarded) 

 will at the age of ten years have approximately 

 eight-year intelligence (still 20 per cent re- 

 tarded). The same holds for children whose 

 mental age is in advance of the real age. 



This discovery has given rise to the use of 

 the "intelligence quotient" (usually called the 

 IQ). By IQ, therefore, we mean simply the 

 ratio of mental age to real age. The ten-year- 

 old of five-year intelligence has an IQ of 50; 

 the ten-year-old of twelve-year intelligence, an 

 IQ of 120; the twelve-year-old of nine-year 

 intelligence, an IQ of 75; the six-year-old of 

 nine-year intelligence, an IQ of 150, etc. 



In calculating the IQ of adult subjects we 

 disregard the years of real age above sixteen, 

 since it has been found that native mental 

 ability improves little beyond that age. The 

 twenty-year-old of twelve-year intelligence, for 

 example, has an IQ of 75 (12^-16=75). 



The Significance of Various Intelligence Quo- 

 tients. The highest-grade cases which find 

 their way into institutions for the feeble- 

 minded rarely test above 75 IQ. Anyone who 

 tests as low as 70 IQ may safely be classified 

 as feeble-minded. Those between 70 and 80 

 IQ may be called border-line cases. They 

 are far from normal, and yet under favorable 

 circumstances they may be able to take their 

 place after a fashion in the social and indus- 

 trial world. 



Tests of unselected school children show that 

 about 1 per cent fall as low as 70 IQ, 2 per 

 cent as low as 75 IQ, and 5 or 6 per cent as 

 low as 80 IQ. On the other hand, the num- 

 ber of dull children is equaled by the number 

 having superior intelligence, and those haying 



