EXPERIMENTS AND OBSERVATIONS 6i 



errors would creep in. It was possible to prolong this 

 extra tap and thus make it appear more dilatory. We 

 need hardly add that henceforth it was within the power 

 of the experimenter to have the tapping executed entirely 

 with the right foot or with the final extra tap of the left 

 foot. Hitherto the view had been current that this lay 

 solely within the pleasure of the horse. 



If the questioner still inclined forward, still remained 

 in the bent posture after Hans had given the final tap 

 with his left foot, the horse would immediately begin to 

 tap once more with his right foot, which had, in the mean- 

 time, become ready for further action. If the head jerk 

 was then made, Hans would bring his right foot back, 

 give the extra tap with his left foot, then resume tapping 

 with the right and thus continue until the questioner once 

 more resumed the erect posture. Thus the horse on one 

 occasion when I wished him to tap lOO, gave — contrary 

 to my desire — the following response; 39 with the right 

 foot, I with the left, 24 with the right, i with the left, 35 

 with the right, and i with the left. Later it became 

 possible for me to cause him to tap i right, i left, i right, 

 I left, etc. I could even get him to tap exclusively with 

 the left foot by standing at his left rather than at his right 

 as had been customary with his questioners. These taps 

 with the left foot were executed in a far less elegant 

 fashion than those with the right foot, and with a great 

 waste of energy. Hans had become a right-handed 

 individual — as it were — as a result of long habit. 



With regard to the distance at which the experimenter 

 directed the horse, the following may be said : The usual 

 distance was one-quarter to one-half meter. This holds 

 for all tests hitherto described. Seventy tests which were 

 made for the purpose of discovering the influence of 



