BIOLOGY IN HUMAN AFFAIRS 



brief treatment of the subject. Fortunately most mental 

 tests have certain important principles in common, and 

 these can perhaps be made clear by giving first an account 

 of the methods of measuring intelligence. 



When one thinks of the measurement of intelligence, 

 one inevitably thinks of Binet, the great French psycholo- 

 gist who labored so diligently in this field for more than 

 twenty years (1890 to 1911). It is Binet more than anyone 

 else to whom we are indebted for modern methods of 

 intelligence testing. It is true that Galton had preceded 

 him by fifteen years in appreciating the importance of 

 individual differences and in the first crude attempts 

 to measure them by means of tests; also that Kraepelin in 

 Germany and Cattell in America antedated Binet in their 

 entrance into this field. It was the genius of Binet, however, 

 that most clearly envisaged the problem and that gave 

 us the first workable methods of testing intelligence. 



The early tests had confined themselves chiefly to the 

 simpler mental functions, such as sensory discrimination, 

 perception, motor coordination, reaction time, and rote 

 memory. Large individual differences were discovered 

 in all these fields, but they were not found to be correlated 

 in any great degree with intelligence in the ordinary sense 

 of that term. Binet, after many explorative researches in 

 which he investigated the relation of these and other 

 traits to intelligence, abandoned tests of the simple mental 

 functions in favor of tests of such complex functions as 

 logical memory, controlled association, comparison of 

 concepts, detection of absurdities, comprehension of 

 difficult situations, definition of abstract terms, problem 

 solving, etc. Such abilities, Binet found, were highly 

 correlated with ability to master the school subjects and 

 with social efficiency. It is in such traits that the recogniz- 

 ably feeble-minded differ most from normal persons, not 

 in the simple sensory, motor, and perceptual functions. 



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