The purpose of this commission was misunderstood, and therefore many were disappointed with the report which it published, ([Supplement II]). Some had been expecting a positive conclusive explanation; the commission recommended further investigation. Some had asked for a solution of the question whether or not the horse was able to think; the commission maintained neither the one, nor the other. Some had indicated as the main condition of a satisfactory investigation, that both Mr. von Osten and Mr. Schillings be excluded from the tests; this was not done.
But the commission—which, by the way, did not give itself this name, since it had been delegated by no one—undoubtedly had the right to formulate its problem as it saw fit, and this was carefully expressed at the beginning of its report as follows: "The undersigned came together for the purpose of investigating the question whether or not there is involved in the feats of the horse of Mr. von Osten anything of the nature of tricks, that is, intentional influence or aid on the part of the questioner." It was this preliminary question, and not whether or not the horse could think, which the commission intended to answer. They proposed to act as a sort of court of honor for the two gentlemen who had been attacked. It is only in this light that even the raison d'être of this body can be understood; for a scientific commission composed of thirteen men, possessed of varying degrees of scientific preparation, would have been an absurd travesty, and it will readily be seen why the two men, who had been attacked, should not be excluded, since it was they, and primarily Mr. von Osten, upon whom the observations were to be made.
To be sure the commission did go one step beyond that which it had proposed to itself, since it added that it believed that unintentional signs of the kind which are at present familiar, were also excluded. This led many to the unwarranted conclusion that the commission had declared that Hans was able to think. Whereas the thing which might have been logically suggested was that instead of the assumption of the presence of independent thinking, the commission may have had in mind unintentional signs of a kind hitherto unknown. I explained this to a reporter of the "Frankfurter Zeitung" (Mr. A. Gold), who had come to me for information, and in his article he made this hypothesis appear as the most probable one.[A] Certain statements of the circus-manager Busch, who speaks of a 'connection' of some sort, go to show that other members of the commission held to the view just stated.
But how did it come to pass that the commission should deny completely the presence of intentional signals, while, as regards the unintended, it excluded only those which were of the known sort? The report clearly shows that the decision as to the absence of voluntary signals was based not merely upon the fact that no such signals had been detected by the most expert observers, but also upon the character of the two men who exhibited the horse, upon their behavior during the entire period, and upon the method of instruction which Mr. von Osten had employed. In the case of unintentional signs, on the other hand, one had to deal with the fact with which physiologists and experimental psychologists are especially familiar, viz., that our conscious states, without our willing it—indeed, even in spite of us—are accompanied by bodily changes which very often can be detected only by the use of extremely fine graphic methods. The following is a more general instance: every mother, who detects the lie or divines the wish in the eyes of the child, knows that there are characteristic changes of facial expression, which are, nevertheless, very difficult of definition.[B]
The commission did not even maintain or believe that unintentional signs within the realm of the senses known to us, were to be excluded. Professor Nagel and I would never have subscribed to any such conclusion. The sentence in question, therefore, could only be interpreted as follows: that signals of the kind that are used intentionally in the training of horses, could not have occurred even as unintended signs, for otherwise Mr. Busch would have detected them. And in order to be observed by him it was immaterial whether they were given purposely or not. The same signs, therefore, which as a result of his observations were declared not to be present, could not be assumed to be involved as unintentional.
For my part I am ready to confess that at this time I did not expect to find the involuntary signals, if any such were involved, in the form of movements. I had in mind rather some sort of nasal whisper such as had been invoked by the Danish psychologist A. Lehmann, in order to explain certain cases of so-called telepathy. I could not believe that a horse could perceive movements which escaped the sharp eyes of the circus-manager. To be sure, extremely slight movements may still be perceived after objects at rest have become imperceptible. But one would hardly expect this feat on the part of an animal, who was so deficient in keenness of vision, as we have been led, by those of presumably expert knowledge, to believe of the horse,—one would expect it all the less because Mr. von Osten and Mr. Schillings would move hither and thither in most irregular fashion while the horse was going through his tapping, and would therefore make the perception of minute movements all the more difficult.
Nor was there anything in the exhibitions given at the same time in a Berlin vaudeville by the mare "Rosa," which might have shattered this belief. For, in the case of this rival of Hans, the movements involved were comparatively coarse. The closing signal consisted in bending forward on the part of the one exhibiting the mare, while up to that point he had stood bolt upright. Most persons were not aware of this, because this change in posture cannot be noticed from the front. I happened to sit to the side and caught the movement every time. It was the same that was noted by Dr. Miessner, another member of the commission, (see [page 256]), but concerning which he did not give me a more complete account. Later I learned through Professor Th. W. Engelmann that the very same movement was employed not long ago, for giving signals to a dog exhibited at Utrecht. This particular movement is very well adapted to commercial purposes, since the spectator always tries to view the performance from a point as nearly in front of the animal and its master as possible, thus making the detection of the trick all the more difficult.
The details of the various experiments made by this commission are given in an excerpt from the records kept by Dr. von Hornbostel, which I showed to a small group of persons a few days after the 12th of September ([Supplement III]). At that time none of the particulars was published, because the commission wished to wait until some positive statement might be made. The public was merely to be assured that a group of reputable men, from different spheres of life, who could have no purpose in hazarding their reputation, believed that the case was one worthy of careful investigation.
I left Berlin on September 17th and did not return until October 3d. In the meantime Mr. Schillings continued the investigation, and was assisted in part by Mr. Oskar Pfungst, one of my co-workers at the Psychological Institute. For the first time a number of tests were now made in which neither the questioner, nor any of those present knew the answer to the problem. Such tests naturally were the first steps toward a positive investigation. The results were such that Mr. Schillings was led to replace his hypothesis of independent conceptual thinking by one of some kind of suggestion. In this he was strengthened somewhat by having noted the fact that in his questions which he put to the horse, he might proceed as far as to ask the impossible. He has always been ready to offer himself in the tests which have been undertaken since then.
On October 13, 1904, together with the two gentlemen mentioned in the beginning of my report, I began my more detailed investigation, and finished on November 29. We worked for several hours on the average of four times each week. I take this opportunity of giving expression of the recognition which is due to the two gentlemen. They were ready to go to the courtyard in all kinds of weather, at times they went without me, and they always patiently discussed the order and method of the experiments and the results. Dr. von Hornbostel had the important task of keeping the records, and Mr. Pfungst undertook the conduct of the experiments. It was he, who, soon after the blinder-tests disclosed the necessary presence of visual signs, discovered the nature of these signs. Without him we might have shown the horse to be dependent upon visual stimuli in general, but we never would have been able to gain that mass of detail, which makes the case valuable for human psychology. But I am tempted to praise not merely his patience and skill, but also his courage. For we must not believe that Mr. von Osten's horse was a "perfectly gentle" animal. If he stood untied and happened to be excited by some sudden occurrence, he would make that courtyard an unsafe place, and both Mr. Schillings and Mr. Pfungst suffered from more than one bite. In this connection I would also express my obligations to Count Otto zu Castell-Rüdenhausen, for his frequent intercession on our behalf with the owner of the horse, and for his many evidences of good-will and helpfulness.