I shall now turn to peculiarities of character, highly humanized, which have been attributed to Hans. His "sympathies" and "antipathies", so-called, were nothing but erroneous appellations for the success or failure on the part of the respective individuals to elicit responses. He who could procure answers frequently, apparently stood high in the horse's favor. That Hans shook his head violently when asked by Mr. von Osten: "Do you like Mr. Stumpf?", and answered in the affirmative the further question: "Do you like Mr. Busch?", was nothing but a confession—unwilling, to be sure—on the part of the master himself. In the first case the master thought "no", in the second instance, "yes", and the two thoughts were accompanied by the corresponding head movements, to which Hans responded mechanically. Hans appeared to be well-disposed toward me, but evidently because I always rewarded him liberally when he answered correctly, and I did not scold him when his responses were wrong, as did Mr. von Osten and Mr. Schillings, who instead of seeking the cause within themselves, were always ready to rebuke Hans for his contrariety and fickleness. The horse did not show, in so far as can be judged at all, any real affection for his master. On the other hand it would be unwarranted to say that, in spite of all rewards, he developed a grudge against all those who bothered him with instruction and examination. Shortly after the close of our experimentation it happened that Hans severely injured his groom by a blow in the face. Yet this man had always been very gentle with the horse and had been forbidden by Mr. von Osten to make Hans solve any problems for him. Experts assure me that we have here to deal, not with a case of "moral insanity", but with a very common experience,—although this view will probably be cavilled at by enthusiastic lovers of horses. The work of so excellent an expert as Fillis,[92] for instance, bears us out in this respect.
The horse's supposed fickleness was nothing but a token of the fact that even those who were accustomed to working with him, did not have him completely in hand. (They simply did not understand how to obtain correct responses from the horse.) It often happened that in the evening, when it had become so dark that the movements of Mr. von Osten could no longer be seen, Hans had to suffer bitter reproaches because he made so many errors. That, in truth, he never was stubborn and that the cause of failure really lay in the questioner, is shown by the fact that the mood, for which he was reproved, would disappear the moment the questioner voluntarily controlled the signals. We may add that there was no basis for the assumption that "he had an uncommon, finely constituted nervous system" or was possessed of a "high degree of nervousness". Both these phrases were often mentioned by way of explanation. Hans was restive, as horses usually are. And besides, he lived a life so secluded (he was never allowed to leave the courtyard) that as a result he was easily disturbed by strange sights and sounds. There was not the slightest trace of the clinical symptoms of neurasthenia—on the contrary he gave the impression of perfect health,—which was curious enough when we remember his rather unnatural mode of life.
Hans's stubbornness was a myth. He was suspected of it whenever the same error occurred a number of times in succession, i. e., when the questioner did not properly regulate his attention ([page 146]) or when he was being controlled by "perseverative tendency", mentioned on [page 149]. Mr. Schillings, who has provided me with material here as elsewhere, relates the following episode which occurred on one such occasion. To one and the same question put alternately by Mr. von Osten and Mr. Schillings, Hans responded correctly, with two taps, to the former, and just as persistently incorrectly, with three taps, to the latter. After Mr. Schillings had suffered this to occur three times he accosted the horse peremptorily: "And now are you going to answer correctly?". Hereupon Hans promptly shook his head, to the great merriment of all those present. (Mr. Schillings had, with no accounted reason, expected a "no".) Hans was called willful whenever the same question was successively answered by different responses, as frequently happened with the increasing tension that characterized the high numbers ([page 145]). He was also regarded as stubborn when no reply at all was forthcoming, as in the tests with the blinders.
Hans's supposed distrust of the questioner, when the latter did not know the answer to the problem, is nothing but a poor attempt to account for the failure of those tests. Hans's distrust of the correctness of his own responses was supposed to be evident from his tendency to begin to tap once more if, after the completion of a task, the questioner did not immediately give expression to some form of approval or disapproval—just as a schoolboy begins to doubt his answer if the teacher remains silent for a short time. In terms of the results of our experimentation this would mean that whenever the questioner did not resume the erect posture, after Hans had given the final tap with the left foot, then the horse would immediately begin once more to tap with the other foot ([page 61]).
As the evil characteristics, so, too, the good. Thus, his precipitancy, which was supposedly evidenced by his beginning to tap before the questioner had enunciated the question, was nothing but a reflection of the questioner's own precipitancy in bending forward ([page 57]). Never did Hans evince the slightest trace of spontaneity. He never spelled, of his own accord, anything like "Hans is hungry," for instance. He was rather like a machine that must be started and kept going by a certain amount of fuel (in the form of bread and carrots). The desire for food did not have to be operative in every case. The tapping might ensue mechanically as a matter of habit—for horses are to a large extent creatures of habit. This lack of spontaneity could hardly be reconciled with the horse's reputation for cleverness. It would not be necessary to touch upon the signs that were supposed to betoken genius: the intelligent eye, the high forehead, the carriage of the head, which clearly showed that "a real thought process was going on inside",—all these, we said, would not need mentioning, if they had not been taken seriously by sober-minded folk. If there is a report that Hans turned appreciatively toward visitors who made some remark in praise of his accomplishments,—it is evidence only of the observer's imaginativeness.
Turning from a consideration of the horse to that of the persons experimenting with him,[AH] the first and most important question that arises is this: How was it possible that so many persons (there were about forty) were able to receive responses from the horse, and many of them on the very first occasion? The answer is not hard to find. All of these persons came to the horse in very much the same frame of mind—which found a similar expression in all, in both posture and movements. And it was these motor expressions of the questioner (aside from the signs for "yes" and "no", which I believe I have adequately explained on [page 98]), that the horse needed as stimuli for his activity.
The next question that arises is: why did only a few persons receive responses regularly from Hans, whereas the greater number were favored only occasionally? What was the selective principle involved? The answer is, that the successful person had to belong to a certain type, which embodied the following essential characteristics.
1. A certain measure of ability and tact in dealing with the horse. As in the case of dealing with wild animals, such as the lion, etc., Hans must not be made uneasy by timidity in the questioner, but must be approached with an air of quiet authority.
2. The power of intense concentration, whether in expectation of a certain sensory impression (the final tap), or in fixing attention upon some idea-content ("yes", "no", etc.). It is only when expectancy and volition are very forceful, that a sufficient release of tension can ensue. This release of tension is accompanied by a change in innervation and results in a perceptible movement. And it was only when the thought of "yes", or "up", etc., was very vivid, that the nervous energy would spread to the motor areas and thence to the efferent fibers, and thus result in the head-movement of the questioner. From infancy we are trained to keep all of our voluntary muscles under a certain measure of control. During the state of concentration just described, this control is relaxed, and our whole musculature becomes the instrument for the play of non-voluntary impulses. The stronger the customary control, the stronger must the stimuli be which can overcome it. The steady unremitting fixation, which resulted in the horse's selection of the cloths, also involves a high degree of concentration.
3. Facility of motor discharge. Great concentration was necessary of course, but not sufficient. Persons in whom the flow of nervous energy tended to drain off over the nerves leading to the glands and the vascular system might betray great tension, not so much by movements as by a flow of perspiration (we have many excellent examples of this given by Manouvrier)[93] or by a violent beating of the heart, blushing and the like,—in short, by secretory and vasomotor effects. Or it is not inconceivable that long dealing with very abstract thoughts might have weakened the tendency of overflow to other parts of the brain, and that therefore the entire discharge is used up in those portions of the brain which are the basis of the intellectual processes. But if expressive movements occur, the motor pathways must be particularly unresisting in order to take up the overflow of psychophysic energy. This is the necessary condition for obtaining the tapping and the head movements on the part of the horse, although for the tapping there is still one other circumstance necessary: viz.,