[Figure 13] (von Allesch) shows the movement accompanying the thought of "up", a slight raise of the head, recorded in the fourth curve. (The thought of "down" is accompanied by a corresponding downward movement.)
Fig. 13.
Figures [14] (von Allesch) and [15] (von Manteuffel) illustrate the nod which is associated with the thought of "yes" in the case of two subjects. It is essentially the same in both: the head is lowered and then raised. The first of the two subjects is more decidedly motor, and his movements therefore were somewhat the more extensive. In the case of the second subject the nod proper is followed by another which is somewhat less extensive.
| Fig. 14. | Fig. 15. |
A number of other experiments were carried out which corresponded with the color-selecting tests made upon Hans. ([Page 78].) Five sheets of white paper, ½ meter long and ¼ meter wide, were arranged in a series upon the floor, ¼ meter apart. A dot marked the middle of each. The experimenter stood at a distance of 7½ meters and directly opposite the middle sheet. At about ½ meter to the right or left of him stood the subject who took the part of the "horse". The problem of the experimenter was to indicate to the "horse" a certain one of the five sheets, but without the use of word or gesture. I at first undertook the rôle of "horse", whereas the others consecutively played the part of questioner. All of them looked fixedly at the sheet which they had in mind. Besides, it usually happened that they would turn at least their heads, and often their bodies, more or less in the direction of the particular sheet—and this without purpose or knowledge on their part, but purely as a result of concentration upon the sheet they wished me to point out. One of the experimenters remarked, quite casually, that he had noted that I always made a better judgment, the more intently he thought of the sheet. Others often admitted that, when I had made an error, they had not imagined the sheet vividly, or had been debating whether or not to decide to think of the neighboring sheet—the one I had designated. This indecision could be noticed by the direction of the eyes. But the following table shows how uniform, on the whole, was the behavior of the various persons when under the guidance of the same impulse. The number of tests was 200 in each case. All errors were of the same character. Neighboring sheets were mistaken for each other, and the errors were never of more than one position to either side. Their number can easily be obtained by subtracting the percentage of correct inferences from the total, 100%.
| Experimenter: | v. A. | B. | C. | Mrs. v. H. | K. | Miss v. L. |
| Correct inferences: | 88% | 88% | 77% | 81% | 77% | 82% |
It will be seen that the number of correct interpretations is quite high and in none of the cases does it deviate far from the mean average of 82%.
I based my judgment as to the direction of the subject's eyes, upon an imaginary line perpendicular to the center of the cornea. (This perpendicular does not always coincide with the subject's line of vision, which was the thing I was after, but this cannot be directly obtained. This, of course, was what made the judgment a rather difficult matter.) My judgment as to the direction of the head I based largely on the direction of the nose, (to express it more accurately: upon the direction of the median plane.) I purposely noted only the position of the experimenter and not the movement which led up