-j^ THE HORSE OF MR. VON OSTEN 



he would begin to tap in response to the same signal, 

 as soon as the experimenter stood farther back. The 

 difference in the two signals, therefore, was very slight, 

 and I repeatedly noted that instead of tapping, as he had 

 been requested, Hans would respond to the Count zu 

 Castell's and Mr. Schillings' questions by a nod of the 

 head. 



If, while standing in the customary position to the 

 right of and facing the horse, the questioner would turn 

 his head a little to the right — a movement which, when 

 seen from the horse's position, would appear to be to the 

 left, — Hans would turn his head to his left. But if on 

 the other hand the questioner would turn slightly to the 

 left, — i. e. seen from the horse's position, to the right, — 

 then Hans would turn his head to his right. And finally, 

 whenever the questioner turned his head first to the right, 

 then to the left, Hans would respond by turning first to 

 his left, then to his right. This, according to Mr. von 

 Osten, signified " zero " or " no ". Since this movement 

 could not be executed by the experimenter while in a 

 stooping position, it can now readily be seen why it was 

 that Hans, instead of shaking his head, always began to 

 tap whenever a placard with " O " upon it, was shown to 

 him in the course of the experiments in which the 

 method was procedure without knowledge on the part of 

 the questioner. The latter expected the horse to tap, and 

 therefore bent forward. Like all of the horse's other forms 

 of response, this, too, was always unsuccessful when- 

 ever the questioner stepped behind the animal. Although 

 Hans had always responded to Mr. von Osten and Mr. 

 Schillings, and at first also to me, by means of the 

 stereotyped movement of the head to the right and then 

 to the left to signify " zero " or " no ", I later succeeded 



