EXPERIMENTS AND OBSERVATIONS 8i 



ing erect, Mr. von Osten always turned head and trunk 

 in the direction of the cloth or placard desired. Hans, 

 keeping his eye on his master, would proceed in that 

 direction. Even after he had already started out, thanks 

 to his large visual field one could control his direction by 

 turning slightly more to the right or to the left. If, 

 however, he had already arrived at the row of placards or 

 cloths, this method ceased to be effective, for then he 

 could no longer see the experimenter. It made no dif- 

 ference whether the cloths lay on the ground, or were 

 suspended, like the placards. 



The following fact justifies the conclusion that the 

 bodily attitude of the questioner was the effective signal. 

 The more numerous the cloths, or the nearer they were 

 placed together, the more difficult one would expect it to 

 be for the horse to select the one indicated by the experi- 

 menter. Such was indeed the case, for the number of 

 errors increased with the number of cloths presented. 



But no matter how many cloths there might be, or how 

 closely they might be placed, it was always possible to 

 indicate either end of the row, for in that case one had 

 merfely to turn to the extreme left or the extreme right, 

 and might even turn beyond the row. Hans seldom 

 failed in these cases, whereas he made many errors when 

 cloths or placards within the series were wanted. 



To turn from the nature and number of Hans's errors, 

 to their distribution, — observation proved the hypothesis 

 that the nearer two cloths lay together, the greater was 

 the chance of their being mistaken one for the other. 

 If we designate as " error i " all those cases in which 

 Hans went to cloth II instead of to cloth I, cloth III 

 instpad of cloth II, to V instead of IV, etc., and as " error 

 2". when, he mistook III for I, IV for II, in fine, when- 



