62 THE HORSE OF MR. VON OSTEN 



change in distance showed that the reaction of the horse 

 upon the customary signal of the head-jerk was accurate 

 up to a distance of three and one-half meters. At a 

 distance of three and one-half to four meters there sud- 

 denly occurred a fall of 60-70% in the number of correct 

 responses. At a distance of four to four and one-half 

 meters only one-third of the responses were correct, and 

 at a distance beyond four and one-half meters there were 

 no correct responses. The greater number of these tests 

 were made in our presence by Mr. von Osten, who was 

 under the impression that we were testing the accuracy of 

 the horse's hearing, whereas we were really testing the 

 accuracy of his perception of movements. 



With regard to the different positions which the experi- 

 menter might assume with reference to the horse, the 

 following may be noted : The normal position was to the 

 right of the horse. If the experimenter stood immediately 

 in front of Hans, the latter 's reaction would be just as 

 accurate, though he would always turn his head and 

 make desperate efforts to see the questioner, even though 

 he was held in short by the reins. When a position im- 

 mediately behind the horse was taken — a somewhat 

 dangerous proceeding, since Hans would at once begin 

 to kick — no response could be obtained until he succeeded 

 in turning far enough around to get the questioner within 

 view. If he was restrained from turning completely 

 around, he would at least turn his head, — and always to 

 the right. One might even turn his back upon Hans 

 during the tests, for the signal for stopping was not 

 obtained from the face of the questioner, but from a move- 

 ment of the head. The following incident will show to 

 what extent the horse had become accustomed to seeing 

 the questioner in a certain definite position. For a long 



