AUTHOR'S PEEFACE 



I undertook for the last German congress of psy- 

 chology, held at Berlin, April, 1912, a general review 

 of the psychological methods of testing intelligence. 

 As I had only an hour at my disposal in my address, 

 I could at that time do little more than outline cer- 

 tain of the main features of this very broad field. It 

 seemed to me, however, hardly desirable to publish 

 the address in the form in which it was given. I 

 felt, on the contrary, that in view of the now ever- 

 increasing interest displayed in the theme both in 

 Germany and elsewhere and in view of the extraordi- 

 narily scattered nature of the literature much of 

 which, by the way, is difficult of access that an ex- 

 position of the topic on a wider scale was demanded. 

 So I have tried to elaborate my original review to 

 this larger scale. I have treated in it three main 

 topics: single tests, the serial method (after Binet- 

 Simon) and the methods of correlation and estima- 

 tion. 



In the form of my treatment, also, I have over- 

 stepped the bounds of the mere ' ' general review. ' ' I 

 have not confined myself to setting down what now 

 exists, but have myself taken an attitude toward the 

 problem, have offered criticisms of the methods and 



