It may be that these truly microscopic movements also play some part in bringing about the success of some of the experiments in telepathy, so-called, (transference of thought from one person to another, ostensibly without any mediation of the senses known to us.) In spite of the huge mass of "experimental evidence" which has been collected, chiefly in England and in America, it appears to me that telepathy is nothing but an unproven hypothesis based upon experimental errors.]

It was assumed, as indicated on page 99, that in the case of Mr. Schillings and myself the movements naturally expressive of "zero" and "no" had been displaced--without our being aware of the fact--by others, viz.: those which the horse required as directives for his reactions. Since this was the case, we tried to discover if a similar displacement could be brought about experimentally. The attempt was successful and we discovered that under suitable conditions we could cause the subject--quite without knowledge on his part,--to establish an "association" between any given concept and any given expressive movement. The following experimental series will serve to illustrate this fact.

Clever Hans — Part 66

I had one of the subjects (von A.) think of "left" and "right" in any order he chose. (The command was purposely given only in a general way: "Think of 'right' or 'left'".). We had agreed that I was to try to guess the mental content of the subject's mind, but I was not to utter a word. Instead, I was to indicate "right" in every case by an arm movement downward, and "left" by a movement upward. To the subject I gave a fictitious but plausible reason for all this. The behavior of the subject took the following course: In the first three tests he moved his eyes to the right when he thought of "right", and to the left when he thought of "left". This was the normal expressive movement. In the fourth test, however, the thought "left" was accompanied by an upward movement of the eyes. Two further tests again showed eye-movements to the right and left. In the seventh test with the idea "left" the eyes moved first to the left and then immediately upward. In the following ten tests the eyes were turned regularly upward at the thought of "left", and downward at the thought of "right", with only one exception which was a normal movement to the left. The normal expressive movements, therefore, were displaced by the artificial, after the seventh test.

Clever Hans — Part 66