26 PSYCHOLOGICAL METHODS OF TESTING INTELLIGENCE 



technical ability. Yet, on the whole, the principle of the con- 

 struction of the profile is too superficial and the coordination of 

 certain tests to certain mental functions, c. g., to volitional acts, 

 is not precise enough to allow us to hope for much success. 



This demand for a system of tests presents such 

 an exceedingly difficult scientific problem that it is 

 perfectly evident that alienists and educators can 

 not solve it as a side issue of their professional work, 

 but that psychology itself will have to undertake the 

 task. It is interesting in this connection to note how 

 psychology attacked the problem along two very dif- 

 ferent lines. I feel that it is important to consider 

 them separately in what follows. Neither of these 

 two lines of effort should be regarded as the only 

 correct one ; each method has its advantages and its 

 disadvantages, and, what is particularly important, 

 each has its special aim for which it is fitted. The 

 method of age- gradation of Binet and Simon permits 

 of a rough gradation of intelligence for the whole 

 range of development of the child ; it is for use in a 

 comparable manner with children of different ages, 

 of different nationality and cultural level, with 

 normal and with feeble-minded children of all 

 grades. The method of rank correlation, on the 

 other hand, is limited thus far to a comparison of the 

 members of a small homogeneous group, but renders 

 it possible to test the gradation of intelligence with- 

 in this group with a precision that the Binet method 

 can not approximate. A considerable amount of ma- 

 terial is already available for the first of these 

 methods, and we shall have to deal with it at some 

 length for that reason. With the second method, on 

 the contrary, our discussion will center upon the out- 

 look for its future development. 



