To elucidate; if the questioner retained the erect position he elicited no response from the horse, say what he 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 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 completely 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 time which elapsed between the last tap and the signal for stopping. These modifications, which had hitherto been paraded as expressions of the horse's psychical power may be illustrated by the following schematic figures (Figures [1]-[4]). In all of them the dotted line c-d represents the ground level; d shows where the horse's right forefoot was located before he began tapping; a and c, respectively, indicate the place to which the foot is lowered during the process of tapping. The unbroken line gives the direction of the back-step.
If Hans, having raised his foot from a to b—preparatory to tapping,—receives the signal at or just before the moment he lowers the foot, he immediately swings it in a wide circle from c back to its original position at d, ([Fig. 1]). As a matter of fact a and c coincide, but are juxtaposed in the diagram for the sake of schematic
utility. This was the usual form of the back-step.
Fig. 1.
If the signal for stopping is given a little after the last tap ([Fig. 2]), i. e., at the time that the foot is already being raised for another tap, then the back-step occurs as a-b-d. The horse thus gives, at the moment it receives the signal for stopping, a changed impulse to the moving foot. The curve, therefore, has a kink at b, and the back-step occurs with seeming hesitancy,—Hans appears not quite certain of his result.
