EXPERIMENTS AND OBSERVATIONS 57 



would. If, however, he stooped over slightly, Hans would 

 immediately begin to tap, whether or not he had been 

 asked a question. It seems almost ridiculous that this 

 should never have been noticed before, but it is easily 

 understood, for as soon as the questioner gave the problem 

 he bent forward — ^be it ever so slightly — in order to 

 observe the horse's foot the more closely, for the foot was 

 the horse's organ of speech. Hans would invariably 

 begin to tap when I stooped to jot down some note I 

 wished to make. Even to lower the head a little was 

 sufficient to elicit a response, even though the body itself 



Fig. I. 



might remain completely erect. Of thirty tests made in 

 this position, twenty-nine were successful. Hans would 

 continue to tap until the questioner again resumed a com- 

 pletely erect posture. If, for instance, I stooped forward 

 after having told the horse to tap 13, and if I purposely 

 remained in this position until I had counted 20, he would, 

 without any hesitation, tap 20. If I asked him to add 3 

 and 4, but did not move until 14 was reached, he would 

 tap 14. Twenty-six such tests gave similar results. 



The reaction of the horse upon such a signal for 

 stopping showed slight modifications according to the 



