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[Illustration: CLEVER HANS]
CLEVER HANS
(THE HORSE OF MR. VON OSTEN)
_A CONTRIBUTION TO EXPERIMENTAL
ANIMAL AND HUMAN
PSYCHOLOGY_
BY
OSKAR PFUNGST
WITH AN INTRODUCTION BY PROF. C. STUMPF,
AND ONE ILLUSTRATION AND FIFTEEN FIGURES
TRANSLATED FROM THE GERMAN
BY
CARL L. RAHN
_Fellow in Psychology in the University of Chicago_
WITH A PREFATORY NOTE BY
JAMES R. ANGELL
_Professor of Psychology in the University of Chicago_
[Illustration]
NEW YORK
HENRY HOLT AND COMPANY
1911
COPYRIGHT, 1911,
BY
HENRY HOLT AND COMPANY
PREFATORY NOTE
[BY JAMES R. ANGELL]
_The University of Chicago_
It gives me great pleasure to accept the invitation of the publishers to
write a word of introduction for Mr. Rahn's excellent translation of
"Der Kluge Hans", a book which in the original has been but little known
to American readers. The present wave of interest in animal life and
behavior renders its appearance peculiarly appropriate.
No more remarkable tale of credulity founded on unconscious deceit was
ever told, and were it offered as fiction, it would take high rank as a
work of imagination. Being in reality a record of sober fact, it verges
on the miraculous. After reading Mr. Pfungst's story one can quite
understand how sedate and sober Germany was for months thrown into a
turmoil of newspaper debate, which for intensity and range of feeling
finds its only parallel in a heated political campaign. That the subject
of the controversy was the alleged ability of a trained horse to solve
complex arithmetical problems may excite gaiety and even derision, until
one hears the details. Scientists and scholars of the highest eminence
were drawn into the conflict, which has not yet wholly subsided,
although the present report must be regarded as quite final in its
verdict.
As for Hans himself, he has become the prototype of a host of less
distinguished imitators representing every level of animal life, and
when last heard from he was still entertaining mystified audiences by
his accomplishments.
But the permanent worth of the book is not to be found in its record of
popular excitement, interesting as that is. It is a document of the very
first consequence in its revelation of the workings of the animal mind
as disclosed in the horse. Animal lovers of all kinds, whether
scientists or laymen, will find in it material of greatest value for the
correct apprehension of animal behavior. Moreover, it affords an
illuminating insight into the technique of experimental psychology in
its study both of human and animal consciousness. Finally, it contains a
number of highly suggestive observations bearing on certain aspects of
telepathy and muscle-reading. All things considered, it may fairly be
said that few scientific books appeal to so various a range of interests
in so vital a way.
Readers who wish to inform themselves of all the personal circumstances
in the case may best read the text just as it stands. Those who desire
to get at the pith of the matter without reference to its historical
settings, may be advised to omit the Introduction by Professor Stumpf of
the University of Berlin, together with supplements II, III and IV.
CONTENTS
PAGE
PREFATORY NOTE (By JAMES R. ANGELL) v
INTRODUCTION (By C. STUMPF) 1
CHAPTER
I. THE PROBLEM OF ANIMAL CONSCIOUSNESS AND "CLEVER HANS" 15
II. EXPERIMENTS AND OBSERVATIONS 30
III. THE AUTHOR'S INTROSPECTIONS 88
IV. LABORATORY TESTS 102
V. EXPLANATION OF THE OBSERVATIONS 141
VI. GENESIS OF THE REACTION OF THE HORSE 212
CONCLUSION 240
SUPPLEMENTS:
I. MR. VON OSTEN'S METHOD OF INSTRUCTION (By C. STUMPF) 245
II. THE REPORT OF SEPTEMBER 12th, 1904 253
III. AN ABSTRACT FROM THE RECORDS OF THE
SEPTEMBER-COMMISSION 255
IV. THE REPORT OF DECEMBER 9th, 1904 261
TABLE OF REFERENCES 267
INTRODUCTION
[BY C. STUMPF]
A horse that solves correctly problems in multiplication and division by
means of tapping. Persons of unimpeachable honor, who in the master's
absence have received responses, and assure us that in the process they
have not made even the slightest sign. Thousands of spectators,
horse-fanciers, trick-trainers of first rank, and not one of them during
the course of many months' observations are able to discover any kind of
regular signal.
That was the riddle. And its solution was found in the unintentional
minimal movements of the horse's questioner.
Simple though it may seem, the history of the solution is nevertheless
quite complex, and one of the important incidents in it is the
appearance of the zooelogist and African traveler, Schillings, upon the
scene, and then there is the report of the so-called Hans-Commission of
September 12, 1904. And finally there is the scientific investigation,
the results of which were published in my report of December 9, 1904.
After a cursory inspection during the month of February, I again called
upon Mr. von Osten in July, and asked him to explain to Professor
Schumann and me just what method he had used in instructing the horse.
We hoped in this way to gain a clue to the mechanism of Hans's feats.
The most essential parts of the information thus gleaned are summarized
in Supplement I. Mr. Schillings came into the courtyard for the first
time about the middle of July. He came as skeptical as everyone else.
But after he, himself, had received correct responses, he too became
convinced, and devoted much of his time to exhibiting the horse, and
daily brought new guests. To be perfectly frank, at the time this seemed
to us a disturbing factor in the investigation, but now we see that his
intervention was a link in the chain of events which finally led to an
explanation. For it was through him that the fact was established beyond
cavil, that the horse was able to respond to strangers in the master's
absence. Heretofore, this had been noted only in isolated cases. Since
it could not be assumed that a well-known investigator should take it
upon himself to mislead the public by intentionally giving signs, the
case necessarily from that time on appeared in the eyes of others in a
light quite different from that in which ordinary circus-tricks would
appear, to which it bore such a striking external resemblance. No matter
how this state of affairs may have arisen in the course of years, no
matter how it might eventually be explained,--the quality of the
extraordinary would necessarily attach itself to this particular case,
as it did.
Of course, to many persons in the interested public the result was
merely that Schillings, also, was placed in the category of deceivers.
On the other hand there were reputable scientists who could not dispose
of the matter in that fashion, and these now openly took their stand
with Schillings and declared that they believed in the horse's ability
to think. Zooelogists especially, saw in von Osten's results evidence of
the essential similarity between the human and the animal mind, which
doctrine has been coming more and more into favor since the time of
Darwin. Educators were disposed to be convinced, on account of the
clever systematic method of instruction which had been used and which
had not, till then, been applied in the education of a horse. In
addition, there were many details which, it seemed, could not be
explained in any other way. So far as I myself was concerned, I was
ready to change my views with regard to the nature of animal
consciousness, as soon as a careful examination would show that nothing
else would explain the facts, except the assumption of the presence of
conceptual thinking. I had thought out the process hypothetically, i. e.,
how one might conceive of the rise of number concepts and arithmetical
calculation along the peculiar lines which had been followed in Hans's
education, and on the basis of the assumption that the beginnings of
conceptual thinking are present in animals. Also, I had too much faith
in human nature to fear lest nothing peculiarly human should remain
after the art of handling numbers should be shown to be common property
with the lower forms. But under no circumstances would I have undertaken
to make a public statement in favor of any particular view in this
extraordinary case, before a thorough investigation, in accordance with
scientific principles, had been made. I expressed this sentiment at the
time, and recommended the appointment of an investigating commission (in
the "Tag" of September 3, 1904).
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'etre_ 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.
[Footnote A: "Frankfurter Zeitung" of September 22, 1904:
"Concerning the question whether the horse was given some sort of
aid, Professor Stumpf expressed himself freely. He said: 'We were
careful to state in our report that the intentional use of the
(actual) means of training, on the part of the horse's teacher, is
out of the question, ... nor are there involved any of the known
kinds of unconscious, involuntary aids. Our task was completed after
we had ascertained that no tricks or aids of the traditional sort
were being employed'." After some remarks on unconscious habituation
and self-training on the part of animals, the writer arrives at the
conclusion that "the horse of Mr. von Osten has been educated by its
master in the most round-about way, in accordance with a method
suited for the development of human reasoning powers, hence in all
good faith, to give correct responses by means of tapping with the
foot. But what the horse really learned by this wearisome process
was something quite different, something that was more in accord
with his natural capacities,--he learned to discover by purely
sensory aids which are so near the threshold that they are
imperceptible for us and even for the teacher, when he is expected
to tap with his foot and when he is to come to rest."]
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]
[Footnote B: "From the productions of the 'thought-readers' we see
how slight and seemingly insignificant the unconscious movements may
be, which serve as signs for a sensitive re-agent. But in this case
no contact is necessary. There would have to be some sort of visible
or audible expression on the part of the questioner. No proof for
this has as yet been advanced."
How any one possessing the power of logical thought could possibly
infer from these words of mine (published in the above-mentioned
article in the "Tag"), that I denied the possibility of the
occurrence of visual signs, is to me incomprehensible. What I did
deny, and still deny, is that up to that time any had been proven to
occur.]
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-Ruedenhausen, for his frequent intercession on our behalf
with the owner of the horse, and for his many evidences of good-will and
helpfulness.
After the publication of this report (Supplement IV), there was still
some further discussion of the case in societies of various kinds and in
the press, but no important objections were raised. A hippologist
thought that men of his calling should have been consulted, a
telepathist believed that telepathists should have been called in. There
was also some further talk of suggestion, will-transference,
thought-reading and the occult, but no attempt was made to elucidate
these vague terms with reference to their application to the case in
hand. Others adhered to the old cry of "fraud," for a share of which Mr.
Pfungst now fell heir. There were a few who felt it incumbent upon
themselves to preserve their 'priority,' and therefore stated with a
show of satisfaction that I had finally 'confessed' myself to hold their
respective points of view. As if there were anything like "confessions"
in science! As if mere affirmations, even though sealed and deposited in
treasure vaults, had any value with reference to a case in which every
manner of supposition had been advanced in lieu of explanation. Why did
they wait so long, if they had convincing proof for their position?
And finally there were disappointed Darwinists who expressed fear lest
ecclesiastical and reactionary points of view should derive favorable
material from the conclusions arrived at in my report. Needless fear.
For lovers of truth it must always remain a matter of inconsequence
whether anyone is pleased or displeased with the truth, and whether it
is enunciated by Aristotle or Haeckel.
Mr. von Osten, however, continued to exhibit Hans, and is probably doing
so still, but in what frame of mind, I dare not judge. The spectators
continue to look on, they are doubly alert to catch movements, and many
of them have learned from Mr. Schillings what kind of movements they are
to expect. But these "initiated" ones regularly return and declare that
there is nothing in the movements and that they simply could not
discover any aids given to the horse. Nothing can so well show how
difficult the case is, and how great the need of a thorough exposition
of the whole matter, than the account given in the following pages of
Mr. Pfungst. Its publication has been delayed on account of the
additional tests made in the laboratory, but we have reason to suppose
that through these additional tests the work has gained in permanent
value. Experimental psychologists will perhaps be greatly interested in
the graphic registration of the minute involuntary movements which
accompany the thought process, and in the artificial association of a
given involuntary movement with a given idea. Likewise the tests on
sense-perception in horses, which have led to essential changes in
hitherto current views, and the critical review of the comprehensive
literature on similar achievements of other animals, will be welcomed by
many.
Before closing these introductory remarks, I would make one more
statement concerning Mr. von Osten. The reader will notice that the
judgment passed upon him in this treatise is placed at the end, whereas
in the report of the commission it came first. This was brought about by
the change that was made in the way of stating the problem. Then the
question discussed was whether 'tricks' were involved; now the question
is: What is the mechanism of the process? The question of the good faith
of the master was taken up once more only because the facts that were
brought to light by the later experimentation seemingly brought forward
new grounds for distrust. But by placing this discussion toward the end
of our report we wished to indicate that everything that is said of the
present status of facts, is quite independent of the view taken
concerning Mr. von Osten. Even assuming that the horse had been
purposely trained by him to respond to this kind of signal, the case
would still deserve a place in the annals of science. For visual signs,
planned and practiced so that they could not only be more readily
perceived by the animal than by man, but could be transferred from their
inventor to others without any betrayal of the secret,--this would be an
extraordinary invention, and Mr. von Osten would then be a fraud, but
also a genius of first rank.
In truth he probably was neither, but I was brief in my report, for
otherwise I would have been obliged to go into more detail than the case
warranted. And a judgment passed upon a human personality is quite a
different matter from a judgment upon a horse. If it is unscientific to
make unqualified statements concerning a horse after the performance of
only a few experimental tests, it is certainly an unwarranted thing to
pass a moral judgment upon a man upon the basis of meagre material.
Anyone who would assume the role of judge should bear in mind that here
too we have more than a hundredfold the material which they could bring
forward, and among it some which, if taken alone, would be more
unfavorable than any that they had. But here all things should be
weighed together, and not in isolation. A former instructor of
mathematics in a German gymnasium, a passionate horseman and hunter,
extremely patient and at the same time highly irrascible, liberal in
permitting the use of the horse for days at a time and again tyrannical
in the insistence upon foolish conditions, clever in his method of
instruction and yet at the same time possessing not even the slightest
notion of the most elementary conditions of scientific procedure,--all
this, and more, goes to make up the man. He is fanatic in his
conviction, he has an eccentric mind which is crammed full of theories
from the phrenology of Gall to the belief that the horse is capable of
inner speech and thereby enunciates inwardly the number as it proceeds
with the tapping. From theories such as these, and on the basis of all
sorts of imagined emotional tendencies in the horse, he also managed to
formulate an explanation for the failure of the tests in which none of
the persons present knew the answer to the problem given the horse, and
also for the failure of those tests in which the large blinders were
applied. And he would often interfere with or hinder other tests which,
according to his point of view, were likely to lead us astray. And yet,
when the first tests with the blinders did turn out as unmistakably
sheer failures, there was such genuine surprise, such tragi-comic rage
directed against the horse, that we finally believed that his views in
the matter would be changed beyond a doubt. "The gentlemen must admit,"
he said at the time, "that after seeing the objective success of my
efforts at instruction, I was warranted in my belief in the horse's
power of independent thought." Nevertheless, upon the following day he
was as ardent an exponent of the belief in the horse's intelligence as
he ever had been.
And finally, after I could no longer keep from him the results of our
investigation, I received a letter from him in which he forbade further
experimentation with the horse. The purpose of our inquiries, he said,
had been to corroborate his theories. On account of his withdrawal of
the horse a few experimental series unfortunately could not be
completed, but happily the major portion of our task had been
accomplished.
THE HORSE OF MR. VON OSTEN
CHAPTER I
THE PROBLEM OF ANIMAL CONSCIOUSNESS AND "CLEVER HANS"
If we would appreciate the interest that has been aroused everywhere by
the wonderful horse solving arithmetical problems, we must first
consider briefly the present state of the problem of animal
consciousness.[C] Animal consciousness cannot be directly gotten at, and
the psychologist must therefore seek to appreciate it on the basis of
the animal's behavior and with the assistance of conceptions borrowed
from human psychology. Hence it is that animal psychology rests upon
uncertain foundations with the result that the fundamental principles
have been repeatedly questioned and agreement has not yet been attained.
The most important of these questions is, "Does the animal possess
consciousness, and is it like the human consciousness?" Comparative
psychologists divide into three groups on this question.
[Footnote C: Since the present treatise is intended for the larger
public, this brief resume will probably be welcome to many.]
The one group allows consciousness to the lower forms, but emphasizes
the assertion that between the animal and the human consciousness there
is an impassable gap. The animal may have sensations and memory-images
of sensations which may become associated in manifold combinations. Both
sensations and memory images are believed to be accompanied by
conditions of pleasure and of pain (so-called sensuous feelings), and
these in turn, become the mainsprings of desire. The possession of
memory gives the power of learning through experience. But with this,
the inventory of the content of animal consciousness is exhausted. The
ability to form concepts[D] and with their aid to make judgments and
draw conclusions is denied the lower forms. All the higher intellectual,
aesthetic and moral feelings, as well as volition guided by motives, are
also denied. Among the ancients this view was held by Aristotle and the
Stoics; and following them it was taught by the Christian Church. It
pervaded all mediaeval philosophy, which grew out of the teachings of
Aristotle and the Church. It is this philosophy, in the form of
Neo-Thomism, which still obtains in the Catholic world.
[Footnote D: Ideas are copies of former sensations, feelings and
other psychic experiences and retain also the accidental signs which
belonged to those earlier experiences. They are images in the
concrete, such as the memory of a certain horse in a certain
definite situation ... say a well fed, long-tailed one standing at a
manger. A concept, on the other hand, is a mental construct which
has its rise in ideas, or memory-images, in that their essential
characteristics are abstracted. For this reason the concept has not
a definite image-content. (Thus the thought of "horse" in general,
is a concept. Not so the thought of a certain individual
horse,----that is an idea, with a definite image-content.)]
During the 17th century, even though temporarily, another conception of
the consciousness of lower forms came to prevail and was introduced by
Descartes, the "Father" of modern philosophy. Far more radical than the
earlier conception, it denied to animals not only the power of abstract
thought, but every form of psychic life whatever, and reduced the lower
form to a machine, which automatically reacted upon external stimuli.
This daring view, however, prevailed for only a comparatively short
period; but owing to the opposition which it aroused, it gave a
tremendous impetus to the study of animal consciousness. Most of the
great philosophers following Descartes, such as Locke, Leibniz, Kant,
and Schopenhauer, however greatly they may have differed in other
points, in this one returned to the Aristotelian point of view.
A third belief avers that animal and human consciousness do not differ
in essentials, but only in degree. This conclusion is regularly arrived
at by those who regard so-called abstract thought itself, as simply a
play of individual sensations and sensation-images, as did the French
and British associationists (Condillac and the Mills). The superiority
of man accordingly consisted in his ability to form more intricate
ideational complexes. Again, this conception of the essential similarity
of the human and the animal psyche has also always been arrived at by
the materialists (from Epicurus to C. Vogt and Buechner) who impute
reason to the animal form as well as to man. The same position is,
furthermore, taken by the evolutionists, including those who do not
subscribe to the doctrines of materialism. It has almost become dogma
with them that there exists an unbroken chain of psychic life from the
lowest protozoa to man. Haeckel, preeminently, though not always
convincingly, sought to establish such a graded series and thus to
bridge the chasm between the human and the animal consciousness.
Two tendencies, therefore, are discernible in animal psychology. The
one seeks to remove the animal psyche farther away from the human, the
other tries to bring the two closer together. It is undoubtedly true
that many acts of the lower forms reveal nothing of the nature of
conceptual thinking. But that others might thus be interpreted cannot be
denied. But need they be thus interpreted?--There lies the dispute. A
single incontrovertible fact which would fulfil this demand, [i.e.,
proof of conceptual thinking], would, at a stroke, decide the question
in favor of those who ascribe the power of thought to the lower forms.
At last the thing so long sought for, was apparently found: A horse that
could solve arithmetical problems--an animal which, thanks to long
training, mastered not merely rudiments, but seemingly arrived at a
power of abstract thought and which surpassed, by far, the highest
expectations of the greatest enthusiast.
And now what was it that this wonderful horse could do? The reader may
accompany us to an exhibition which was given daily before a select
company at about the noon hour in a paved courtyard surrounded by high
apartment houses in the northern part of Berlin. No fee was ever taken.
The visitor might walk about freely and if he wished, might closely
approach the horse and its master, a man between sixty and seventy years
of age. His white head was covered with a black, slouch hat. To his left
the stately animal, a Russian trotting horse, stood like a docile pupil,
managed not by means of the whip, but by gentle encouragement and
frequent reward of bread or carrots. He would answer correctly, nearly
all of the questions which were put to him in German. If he understood a
question, he immediately indicated this by a nod of the head; if he
failed to grasp its import, he communicated the fact by a shake of the
head. We were told that the questioner had to confine himself to a
certain vocabulary, but this was comparatively rich and the horse
widened its scope daily without special instruction, but by simple
contact with his environment. His master, to be sure, was usually
present whenever questions were put to the horse by others, but in the
course of time, he gradually responded to a greater and greater number
of persons. Even though Hans did not appear as willing and reliable in
the case of strangers as in the case of his own master, this might
easily be explained by the lack of authoritativeness on their part and
of affection on the part of Hans, who for the last four years had had
intercourse only with his master.
Our intelligent horse was unable to speak, to be sure. His chief mode of
expression was tapping with his right forefoot. A good deal was also
expressed by means of movements of the head. Thus "yes" was expressed by
a nod, "no" by a deliberate movement from side to side; and "upward,"
"upper," "downward," "right," "left," were indicated by turning the head
in these directions. In this he showed an astonishing ability to put
himself in the place of his visitors. Upon being asked which arm was
raised by a certain gentleman opposite him, Hans promptly answered by a
movement to the right, even though seen from his own side, it would
appear to be the left. Hans would also walk toward the persons or things
that he was asked to point out, and he would bring from a row of colored
cloths, the piece of the particular color demanded. Taking into account
his limited means of expression, his master had translated a large
number of concepts into numbers; e. g.:--the letters of the alphabet,
the tones of the scale, and the names of the playing cards were
indicated by taps. In the case of playing cards one tap meant "ace," two
taps "king," three "queen," etc.
Let us turn now to some of his specific accomplishments. He had,
apparently, completely mastered the cardinal numbers from 1 to 100 and
the ordinals to 10, at least. Upon request he would count objects of all
sorts, the persons present, even to distinctions of sex. Then hats,
umbrellas, and eyeglasses. Even the mechanical activity of tapping
seemed to reveal a measure of intelligence. Small numbers were given
with a slow tapping of the right foot. With larger numbers he would
increase his speed, and would often tap very rapidly right from the
start, so that one might have gained the impression that knowing that he
had a large number to tap, he desired to hasten the monotonous activity.
After the final tap, he would return his right foot--which he used in
his counting--to its original position, or he would make the final count
with a very energetic tap of the left foot,--to underscore it, as it
were. "Zero" was expressed by a shake of the head.
But Hans could not only count, he could also solve problems in
arithmetic. The four fundamental processes were entirely familiar to
him. Common fractions he changed to decimals, and _vice versa_; he could
solve problems in mensuration--and all with such ease that it was
difficult to follow him if one had become somewhat rusty in these
branches. The following problems are illustrations of the kind he
solved.[E] "How much is 2/5 plus 1/2?" Answer: 9/10. (In the case of all
fractions Hans would first tap the numerator, then the denominator; in
this case, therefore, first 9, then 10). Or again: "I have a number in
mind. I subtract 9, and have 3 as a remainder. What is the number I had
in mind?"--12. "What are the factors of 28?"--Thereupon Hans tapped
consecutively 2, 4, 7, 14, 28. "In the number 365287149 I place a
decimal point after the 8. How many are there now in the hundreds
place?"--5. "How many in the ten thousandths place?"--9. It will be
noticed, therefore, that he was able to operate with numbers far
exceeding 100, indeed he could manipulate those of six places. We were
told that this, however, was no longer arithmetical computation in the
true sense of the term; Hans merely knew after the analogy of 10 and 100
that the thousands take the fourth place, the ten-thousands the fifth,
etc. If an error entered into Hans' answer, he could nearly always
correct it immediately upon being asked: "By how many units did you go
wrong?"
[Footnote E: All examples mentioned are cited from extant works of
various observers.]
Hans, furthermore, was able to read the German readily, whether written
or printed. Mr. von Osten, however, taught him only the small letters,
not the capitals. If a series of placards with written words were placed
before the horse, he could step up and point with his nose to any of the
words required of him. He could even spell some of the words. This was
done by the aid of a table devised by Mr. von Osten, in which every
letter of the alphabet, as well as a number of diphthongs had an
appropriate place which the horse could designate by means of a pair of
numbers. Thus in the fifth horizontal row "s" had first place; "sch"
second, "ss," third, etc.; so that the horse would indicate the letter
"s" by treading first 5, then 1, "sch," by 5 and 2, "ss" by 5 and 3.
Upon being asked "What is this woman holding in her hand?" Hans spelled
without hesitation: 3, 2; 4, 6; 3, 7; i. e., "Schirm" (parasol). At
another time a picture of a horse standing at a manger was shown him and
he was asked, "What does this represent?" He promptly spelled "Pferd"
(horse) and then "Krippe" (manger).
He, moreover, gave evidence of an excellent memory. In passing we might
also mention that he knew the value of all the German coins. But most
astonishing of all was the following: Hans carried the entire yearly
calendar in his head; he could give you not only the date for each day
without having been previously taught anew, but he could give you the
date of any day you might mention. He could also answer such inquiries
as this: "If the eighth day of a month comes on Tuesday, what is the
date for the following Friday?" He could tell the time to the minute by
a watch and could answer off-hand the question, "Between what figures is
the small hand of a watch at 5 minutes after half-past seven?" or, "How
many minutes has the large hand to travel between seven minutes after a
quarter past the hour, and three quarters past?" Tasks that were given
him but once would be repeated correctly upon request. The sentence:
"Bruecke und Weg sind vom Feinde besetzt" (The bridge and the road are
held by the enemy), was given to Hans one day and upon the following day
he tapped consecutively the 58 numbers which were necessary for a
correct response. He recognized persons after having seen them but
once--yes, even their photographs taken in previous years and bearing
but slight resemblance.
A corresponding high degree of sensory activity seemed to accompany
these astonishing feats of memory and reason. Although the horse is not
usually credited with a very keen sense of vision, Hans was able to
count the windows of distant houses and the street urchins climbing
about on neighboring roofs. He had an ear for the most subtle nuances of
the voice. He caught every word,--no matter how softly it was spoken--so
that we were not allowed to whisper the answer to a problem, even when
standing at a distance of several yards, since it would be
equivalent--so Mr. von Osten declared--to giving the result to the
horse.
Musical ability also comes into the category of Hans' accomplishments.
He possessed, not only an absolute tone consciousness--a gift granted to
few of us in the human world--which enabled him to recognize a note
sounded or sung to him as c, d, etc. (within the once accented scale of
c-major), but also an infallible feeling for intervals, and could
therefore determine whether two tones, sounded simultaneously, composed
a third or fifth, etc. Without difficulty he analyzed compound clangs
into their components; he indicated their agreeableness or
disagreeableness and could inform us which tones must be eliminated to
make consonance out of dissonance. C, d and e were given simultaneously
and Hans was asked: "Does that sound pleasant?" He shook his head. "What
tone must be omitted to make it pleasant?" Hans trod twice--indicating
tone "d." When the seventh chord, d-f-a-c, was sounded, he shook his
head disapprovingly. He evidently was old-fashioned in his musical
tastes and not agreeably disposed toward modern music, so he indicated
by tapping that the seventh, c, would have to be eliminated; thus
changing the seventh chord to a minor chord in order to obtain harmony.
When asked what tones might not be given simultaneously with the fourth
and sixth, Hans indicated consecutively the third, fifth and seventh;
that the first might be added, he was ready to admit. Finally, he was
familiar with not less than thirteen melodies and their time.
Not only in the high degree of development of the senses and the
intellect, but also in that of the feeling and the will, did Hans
possess a decided individuality. Being of a high-strung and nervous
temperament and governed by moods, he evinced strong likes and dislikes,
and frequently displayed an annoying stubbornness,--a fact often dwelt
upon by Mr. von Osten. He had never felt the whip, and therefore often
persisted in wilfully answering the simplest questions incorrectly and a
moment later would solve, with the greatest ease, some of the most
difficult problems. Whenever any one asked a question without himself
knowing the answer, Hans would indulge in all sorts of sport at the
questioner's expense. We were told that the sensitive animal could
easily perceive the questioner's ignorance and would therefore lose
confidence in, and respect for, him. It was felt to be desirable,
however, to have just such cases with correct responses. Often, too,
Hans would persist in giving what seemed an incorrect reply, but which
was later discovered to be correct. On the other hand it was useless to
try to get answers upon topics of which he knew nothing. Thus he ignored
questions put in French or Latin and became fidgety, thereby showing the
genuineness of his achievements; but upon topics with which he was
familiar he could not be led astray. Indeed, there was nothing but
language lacking to make him almost human and the intelligent animal was
declared by experienced educators to be at about the stage of
development of a child of 13 or 14 years.
This wonderful horse, which in the opinion of its friends was the means
of deciding in the affirmative the old, old, question of the
rationality of the lower forms and thus changing radically the existing
Weltanschauung, aroused world-wide interest. A flood of articles
appeared in the newspapers and magazines, two monograph[1, 2] attempts at
explanation were devoted to him.[F] He was made the subject of popular
couplets, and his name was sung on the vaudeville stage. He appeared
upon picture post-cards and upon liquor labels, and his popularity was
shown by his reincarnation in the form of children's playthings. Many
personages of note who had seen the horse's exhibitions, declared, some
of them in public statements, that they were now convinced. Among these,
besides Mr. Schillings, were naturalists of note; e. g.: the African
explorer Prof. G. Schweinfurth, Dr. Heinroth and Dr. Schaeff, the
director of the zoological garden in Hanover; there were likewise
horse-fanciers of first-rank, such as General Zobel, and the well-known
hippological writer Major R. Schoenbeck. Again, the well-known
zooelogist, K. Moebius, writing in the "National-zeitung" declared he was
convinced of the horse's power to count and to solve arithmetical
problems. He also said that he believed the horse's memory and acute
power of sense-discrimination to be at the root of the matter. Those who
gleaned all their knowledge of the horse from newspaper reading were
satisfied to arrest judgment, or, on the other hand, became indignant at
the supposed imposition on the part of the gentleman of leisure and at
the gullibility of the public. Some would of course attempt explanations
on the basis of older facts. Here we have two points of view.
[Footnote F: The works referred to in the text are to be found listed
on pages 267 ff.]
Some tried to explain the whole thing on the basis of purely mechanical
memory and would thus allow the title "learned" but not "intelligent"
Hans. If, for instance, he was able to indicate the component of a clang
of three tones, it was not because he had the power to analyze the
tone-complex, but because he was able to see the stops of the harmonica
and was accustomed to give one tap for every stop which was closed. If
he was able to tell time by the watch, it was not because he read it,
but because he was always asked at the same hour of the day (which, of
course, was contrary to fact) and because he had learned by heart the
necessary number of taps. They also said that his manifold arithmetical
achievements were merely the expression of a remarkable memory; that in
the animal brain, lying fallow for centuries, there was stored up a
tremendous amount of energy, which here had been suddenly released. They
justified their point by calling to mind, in this connection, the
wonderful memory of primitive races. The authors of the two monographs
already mentioned, Zell and Freund, adopted this 'mnemotechnic'
interpretation, and the latter considered that he had disposed
definitely of the problem in designating the horse--a "four-legged
computing machine."
Another group would not even allow Hans the glory of a wonderful memory.
He knew nothing. Rather was he to be regarded as a stupid Hans, and
totally dependent upon signs or helps given by his master. Only a very
few believed, however, that such signs--the nature of which was quite
unknown or regarding which only vague unsubstantiated suppositions were
advanced--were given unintentionally. Most of the critics openly averred
that we here had to do with intentional control, in other words, with
tricks. But not only did stupid orthodoxy dispose of the matter in this
way, but also the enlightened, who believe everything unusual to be
contrary to reason. They put the Hans problem on a level with
spiritualism, and were convinced that if the veil were removed a crass
imposition would be revealed. Professional trainers who regarded
themselves as well informed did not hesitate to give expression to this
same view, even though they had observed Hans inadequately or not at
all.
The defenders of this second point of view were not at a loss to point
out the signs supposed to be given to Hans. One of these believed he had
discovered the primary means for giving these signs in the slouch hat of
Mr. von Osten. It was no accident, they said, that Mr. Schillings wore a
slouch hat when he experimented with the horse. It is sufficient to note
that Mr. Schillings was usually bare-headed or wore only a cap when he
tested the horse. Another accused, in like fashion, the long coat of the
experimenter; a third, who "had had opportunity to observe Hans on
several occasions," declared with equal certainty that the cue lay in
the movements of the hand as it was thrust into the pocket filled with
carrots. One circus-star declared, that the trick lay in eye movements,
another such star declared it lay in the movements of the hand. A sixth
discovered that the signs were "manifold" and adds, "to be sure, the
trainer must have a fund of such signs in order to prevent
embarrassment." Such a hypothesis is itself, it would seem, one of
embarrassment. On the other hand, there were many first-class observers
who vainly tried to discover regularly recurring signs; among them the
only professional trainer,--who had devoted any satisfactory length of
time to the horse and had also sought diligently for the signs in
question--said, "I was fully convinced that I would be able to explain
the problem in this way, but I was mistaken." The president of the
"Internationale Artisten Genossenschaft," a person who knew all the
usual means of control in trick performances, went over to the other
side as a result of his observations.
There were others who sought for auditory signs. The opinion was
expressed that "Hans was unable to answer the simplest question such as
'What is two plus three?' whenever the questioner's tone of voice
differed from that of the master's." Another put chief stress upon the
changing inflection; furthermore, a "high degree of auditory
sensitivity" was often offered in explanation.
The sense of smell was also made to bear some burdens. With its help,
for instance, Hans was believed to be able to recognize the photograph
of some one present, supposing, of course, that the person had carried
the picture about with him, thus allowing it to be impregnated with his
peculiar personal odor. One even suggested that the heat radiating from
the questioner's body and the electric stimulus conducted underground to
Hans's foot were sufficient explanation for his remarkable feats.
Even the so-called N-rays, of one-day fame, which were supposed to
radiate from the human brain when in activity, were offered as a
solution. A similar thing may have been in the mind of the "natural
philosopher" who even after the publication of the December report,
wrote as follows in one of the journals: "On the basis of most careful
control, I have come to the conclusion, that the brain of the horse
receives the thought-waves which radiate from the brain of his master;
for mental work is, according to the judgment of science, physical
work." Of the same character are the explanations of two others, one of
whom declares that Hans was acting "under the magnetic influence of
man", while the other declared that "hypnotic suggestion is involved",
and, ignoring attested facts, tells us that, "The horse can execute the
commands of another only when the master, with whom it is 'en rapport',
wills that it shall obey." We may close the catalogue of explanations
with one more, which, in spite of its vagueness, found many defenders,
viz: suggestion. Without defining this conception more specifically and
without the slightest notion of the peculiar difficulties which it
involves (L. Loewenfeld in his "Handbuch des Hypnotismus" [Wiesbaden,
1901, pp. 35ff.] cites twenty different definitions of the term given by
as many authors) a critic writes: "The astounding phenomenon of an
animal apparently possessing human reason is to be attributed solely to
suggestion". Having referred to a dog trained for the vaudeville-stage,
the gentleman concludes that, "our intelligent horse, as well as the
dog, is simply of fine nervous organization and hence highly susceptible
to suggestions".
What was to be done, with this mass of conflicting explanations?
Everyone considered his own opinion the only correct one, without,
however, being able to convince anyone else. The need here was not
simple affirmation, but proof.