One more experiment which I made will close the discussion. The following colors were placed from right to left: orange, blue, red, yellow, black, green. I turned my back upon them, and therefore could guide the horse by verbal commands only. I asked him to bring the orange. Hans approached the yellow. I now called three times, allowing a short interval between the calls. At the first "Go!" he passed from the yellow to the red, at the second from the red to the blue, and at the third from the blue to the orange, which he then proceeded to pick up and bring to me. I had noted this same thing in Mr. von Osten's tests, although there, there were often other factors entering in. By exercising the utmost precision in facing the cloths, and by using, in addition, suitable oral signs, I succeeded in getting Hans to bring, successively, each one of the six cloths in the row, and without a single error,—and all this in the presence of Mr. Schillings who did not have the slightest notion of the secret of my success.
We need hardly say, in passing, that all that was true of the tests with colored cloths, was also true of the tests in which the placards were used. It was all the same to the horse whichever was placed before him.
We have thus tested all of the horse's supposed achievements. None of them stood the critical test. It would have been gratifying to have repeated some of the experiments and to have made Hans the object of further psychological investigations, but unfortunately he was no longer at my disposal after the publication of the report of the December-Commission. Some may say that we have had almost enough of a good thing, but we must bear in mind that many of the tests which were carried out,—such as those in which the method was that of "procedure without knowledge", those in which the ear-muffs were used, those in which distractions were introduced,—had previously been made by other persons (see pages [41f], [45], [63]), and with other results, than ours. A more thorough test, therefore, would have been doubly desirable.
FOOTNOTES:
[G] The expressions questioner and experimenter are used interchangeably in this treatise.
[H] Throughout this treatise I am using the word "sign," or "signal," whereas all other writers who have touched upon the Hans-problem, have always spoken of "aids." Following von Sanden,[4] however, I would distinguish clearly between the two. I would designate as aids all immediate stimulations of the horse's body (i. e. by means of contact), which have been designed with reference to the animal's physiological movement-mechanism in such a way that they truly 'aid' him in the production of the required movements. I would regard as signs on the other hand, all stimulations (whether mediate or immediate) which are selected without especial regard to the anatomy or physiology of the horse, and bear no inseparable relation to the thing to be done but are associated with it at the will of the trainer. The rider's use of reins, and control by means of leg-pressure and manner of sitting in the saddle, and the driver's use of the lines,——all these, then are aids. A simple pull at the reins, however, is not an aid, but a sign. The whip may be used for giving signs as well as aids,——the latter, when it does the work of the spur or of the pressure with the knees, as is the case with ladies' riding-horses and in lunging. All calls and all movements of the hand or head merely, on the part of the trainer, are to be regarded as signs.
[I] During the tests Mr. von Osten nearly always wore a slouch hat with a wide rim. The rim, of course, always moved with the head, and made the movements appear on a larger scale, (in the ratio of about 3:2, as I was able to ascertain later by graphic methods). But observation was successful, even at a distance of a meter and a half, when he worked with head uncovered. And even if head and forehead were covered entirely, it was still possible to note the movements by watching the eye-brows. When Mr. Schillings and the rest of us worked with the horse, we either went bare-headed or wore only a very small cap.
[J] For the benefit of those who are familiar with reaction-time experiments of this kind, I would state the following: The reaction to the head-jerk, on account of the minuteness of the latter, was sensory throughout, and therefore all precipitate reactions are entirely wanting. The reaction to the back-step was, like the preceding one, a reaction to a visual cue. (Hans's tapping was almost quite inaudible). Both stop-watches were carefully regulated. In order to eliminate also the constant error which might possibly arise as a result of some difference in the functioning of their pressure-mechanism, the two watches were always exchanged in the different series of tests, by the observer of the man and the observer of the horse. The two time-measurements obtained by the two observers contained, of course, the reaction-times of the observers themselves. In order to equalize the constant error which thereby arose, it was arranged that each observer should react alternately now to the man, now to the horse. In order to be perfectly safe, the reaction-times of those concerned, (von Hornbostel, Pfungst, Schumann and Stumpf), were later determined in the laboratory by means of the carefully regulated Hipp chronoscope. Separate determinations were made of the reactions to the head-jerk and to an imitation of the horse's back-step. Then the time which one observer took to react upon a head-jerk, was compared with the reaction-times of the other observers to the back-step. Since the greatest difference which was found in this comparison, did not exceed one-tenth second, the results obtained in the courtyard required no correction.
[K] See [page 126] on the corresponding reaction-time in the case of man. Similar tests have been made in the case of animals in only one instance, and that for dogs, by E. W. Weyer.[5] But, as might have been expected, they did not yield any satisfactory results.
[L] Mr. Schillings, however, did succeed in making a number of tests with the co-operation of others who had never before worked with the horse. These tests were made under the following conditions: The horse was standing in his stall, when Mr. Schillings and another gentleman approached him. There was no one else present. Mr. Schillings, who tried to remain as passive inwardly, as possible, asked his partner to think consecutively of different numbers between one and 20, which thus were known to him alone. Hans was then commanded by Mr. Schillings to tap the numbers, which he did, to the great astonishment of the men, and especially of Mr. Schillings. In like manner Mr. Sander, a staff physician in the marine, received—so he writes me—three correct responses to four questions which he put to the horse. It happened also in the case of two scientific men and finally, too, in my own case when I first came in contact with the horse, (see [page 88]). The horse's reaction was brought about in the same way in every one of these instances. Mr. Schillings, in bending forward slightly, thereby started the horse a-tapping, and his companion—just as innocently—interrupted the process by means of a movement of his head, when the right number of taps was reached.