236 THE HORSE OF MR. VON OSTEN 



an intention to deceive the public, but a case of pure self- 

 deception.* 



This self-deception is easily understood when we con- 

 sider the two predominent characteristics of the man : the 

 pedantry of the pedagogue, and his^groneness to be pos- 

 "sessed by a single ideaj which is a peculiarity "of those of 

 an inventive turn of mind. Adhering closely to a pre- 

 formed plan, he carefully and narrowly circumscribed 

 the scope and order of instruction. He would not go on 

 to the number 5 if he were not thoroughly convinced that 

 the 4 had been completely mastered, nor would he go on 

 to a more difficult problem in multiplication, until he felt 

 certain that Hans was entirely proficient in the problems 

 of the simpler sort. If he had ever put a question to 

 Hans before its regular order, he would have discovered, 

 to his amazement, that there really existed no difficulties 

 for Hans, and also that the horse really required no ap- 

 preciable time to acquire new material. Mr. von Osten 

 would have had a like experience if he had asked Hans 

 concerning the value of Chinese coins or the logarithm 

 of 1000. However, he never did anything of the kind, 

 but always adhered closely to his plan. He required the 

 questioner to say : " 2 and 2 ", and never " 2 plus 2 ". 

 Nor were capitals or Latin script to be used in the writ- 

 ten material. And if upon request he did so, he did it, 

 without faith in the result, and hence there was failure. 



* P. Wasmann, S. J. in the third edition of his book, " Instinkt und 

 Intelligenz im Tierreich " (Freiburg, Herder, 1905), discusses the case 

 of Hans and quotes from a letter I wrote him concerning the matter. 

 In the quotation an error has crept in, wljich I -would here correct. 

 The statement is ascribed to me that " Hans differs from other horses 

 only in his extraordinary power of observation, an unintentional by- 

 product of intentional training," whereas in my letter I said : " uninten- 

 tional by-product of intentional education.'' 



