Clever Hans (the horse of Mr. Von Osten) a contribution to experimental animal and human psychology

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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

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CopyRIGHT, 1911,
BY
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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 ap-
propriate.

No more remarkable tale of credulity founded on un-
conscious 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 ver-
dict.

vi PREFACTORY NOTE

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 revela-
tion 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 ex-
perimental psychology in its study both of human and ani-
mal 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 per-
sonal 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)

INTRODUCTION (By C. STUMPF) . . . . I
CHAPTER
IL THE PROBLEM OF ANIMAL CONSCIOUSNESS AND ‘‘ CLEVER

Hans ” F ‘ i . . 5
II, EXPERIMENTS AND OBSERVATIONS . m 3 30
III. THE AUTHOR’s INTROSPECTIONS . ‘ és s 88
IV. LaBoraTory TESTS F ‘ ry fi . 102
V. EXPLANATION OF THE OBSERVATIONS * z . I4q1
VI. GENESIS OF THE REACTION OF THE HORSE ,. é 212
CONCLUSION ‘ . < s . * . 240

SUPPLEMENTS :
I. Mr. von OSTEN’s METHOD oF INSTRUCTION (By C. STUMPF) 245

II. Tue REpoRT OF SEPTEMBER 12th, 1904) . . « 253

III. AN ABSTRACT FROM THE RECORDS OF THE SEPTEMBER
CoMMISSION ‘ . a : » 255

VI. Tue Report oF DECEMBER goth, 1904 . ° 261

TABLE OF REFERENCES . ‘i . ° 3 « 267

INTRODUCTION
[By C. Srumpr]

A Horse that solves correctly problems in multiplica-
tion and division by means of tapping. Persons of unim-
peachable honor, who in the master’s absence have re-
ceived 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 ques-
tioner.

Simple though it may seem, the history of the solu-
tion is nevertheless quite complex, and one of the im-
portant incidents in it is the appearance of the zodlogist
and African traveler, Schillings, upon the scene, and
then there is the report of the so-called Hans-Commis-
sion of September 12, 1904. And finally there is the
Scientific investigation, the results of which were pub-
lished 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
1

6 INTRODUCTION

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 es-
pecially familiar, viz., that our conscious states, without
our willing it—indeed, even in spite of us—are accom-
panied by bodily changes which very often can be de-
tected 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.*

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 in-

* “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 ex-
pression 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 ar-
ticle 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.

7a

INTRODUCTION 7

tentionally in the training of horses, could not have oc-
curred 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 un-
intentional.

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 in-
voked 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 there-
fore make the perception of minute movements all the
more difficult. s

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 tais rival of Hans, the movements involved were com-
pari.tively coarse. The closing signal consisted in bend-
ing forward on the part of the one exhibiting the mare,

8 INTRODUCTION

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, an-
other 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 pur-
pose 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 con-
tinued the investigation, and was assisted in part by Mr.
Oskar Pfungst, one of my co-workers at the Psycho-
logical 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. Siuch

INTRODUCTION 9

tests naturally were the first steps toward a positive in-
vestigation. The results were such that Mr. Schillings
was led to replace his hypothesis of independent concep-
tual 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 psychol-
ogy. 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 court-
yard an unsafe place, and both Mr. Schillings and Mr.

10 INTRODUCTION

Pfungst suffered from more than one bite. In this con-
nection I would also express my obligations to Count:
Otto zu Castell-Riidenhausen, for his frequent interces-
sion 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 im-
portant 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 sugges-
tion, 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 satisfac-
tion 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 con-.
clusions arrived at in my report. Needless fear. For
lovers of truth it must always remain a matter of incon-
sequence whether anyone is pleased or displeased with

INTRODUCTION Ir

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 ac-
count 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 sup-
pose that through these additional tests the work has
gained in permanent value. Experimental psychologists
will perhaps be greatly interested in the graphic regis-
tration of the minute involuntary movements which ac-
company the thought process, and in the artificial asso-
ciation 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 litera-
ture 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

12 INTRODUCTION

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 experi-
mentation 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 as-
suming 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 extraor-
dinary 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. Anda
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 rdle 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

INTRODUCTION 13

weighed together, and not in isolation. A former in-
structor of mathematics in a German gymnasium, a pas-
sionate 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 con-
ditions 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 in-
wardly 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.” Never-
theless, upon the following day he was as ardent an ex-

14 INTRODUCTION

ponent 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”

Ir 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.*
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 prin-
ciples 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.

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

* Since the present treatise is intended for the larger public, this
brief resumé will probably be welcome to many.

15

16 THE HORSE OF MR. VON OSTEN

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 * 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 Aris-
totle and the Stoics; and following them it was taught
by the Christian Church. It pervaded all medizval
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.
During the 17th century, even though temporarily, an-
other 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

* 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, isa 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.)

ANIMAL CONSCIOUSNESS 17

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 conscious-
ness 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 in-
dividual 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 ar-
rived at by the materialists (from Epicurus to C. Vogt
and Biichner) 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, preéminently, 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

18 THE HORSE OF MR. VON OSTEN

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 in-
terpreted ?—There lies the dispute. A single incontrovert-
ible fact which would fulfil this demand, [i.e., proof of
conceptual thinking], would, at a stroke, decide the ques-
tion 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 im-

ANIMAL CONSCIOUSNESS 19

port, 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 di-
rections. 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 op-
posite 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

20 THE HORSE OF MR. VON OSTEN

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 accomplish-
ments. He had, apparently, completely mastered the
cardinal numbers from 1 to 100 and the ordinals to Io, 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 in-
telligence. 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 pro-
cesses 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.* “How much is ?
plus 4?” Answer: 7. (In the case of all fractions Hans
would first tap the numerator, then the denominator; in

* All examples mentioned are cited from extant works of various
observers.

ANIMAL CONSCIOUSNESS ai

this case, therefore, first 9, then 10). Or again: “I have
a number in mind. I subtract 9, and have 3 as a re-
mainder. 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?”—g. It will be noticed, there-
fore, that he was able to operate with numbers far ex-
ceeding 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?”’
Hans, furthermore, was able to read the German read-
ily, whether written or printed. Mr. von Osten, how-
ever, 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 hori-
zontal 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

22 THE HORSE OF MR. VON OSTEN

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:
“Brticke 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

ANIMAL CONSCIOUSNESS 23

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 disap-
provingly. 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,

24 THE HORSE OF MR. VON OSTEN

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 fre-
quently 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 ‘in-
dulge in all sorts of sport at the questioner’s expense.
We were told that the sensitive animal could easily per-
ceive 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 cor-
rect responses. Often, too, Hans would persist in giving
what seemed an incorrect reply, but which was later dis-.
covered 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 genuine-
ness 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

ANIMAL CONSCIOUSNESS 28

old, old, question of the rationality of the lower forms
and thus changing radically the existing Weltan-
schauung, aroused world-wide interest. A flood of ar-
ticles appeared in the newspapers and magazines, two
monograph ?)* attempts at explanation were devoted to
him.* 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. Schwein-
furth, Dr. Heinroth and Dr. Schaff, the director of the
zodlogical garden in Hanover; there were likewise
horse-fanciers of first-rank, such as General Zobel, and
the well-known hippological writer Major R. Schoen-
beck. Again, the well-known zodlogist, K. Mobius,
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-dis-
crimination to be at the root of the matter. Those
who gleaned all their knowledge of the horse from news-
paper reading were satisfied to arrest judgment. or, on
the other hand, became indignant at the supposed im-
position 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.

* The works referred to in the text are to be found listed on pages
267 ff.

26 THE HORSE OF MR. VON OSTEN

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 in-
stance, 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 arith- |
metical 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 ‘ mnemo-
technic’ 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,

ANIMAL CONSCIOUSNESS 27

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 con-
trary 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 inad-
equately 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. Schil-
lings 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 dis-
cover regularly recurring signs; among them the only
professional trainer,—who had devoted any satisfactory

28 THE HORSE OF MR. VON OSTEN

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 “ Inter-
nationale 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 bur-
dens. 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 impreg-
nated with his peculiar personal odor. One even sug-
gested that the heat radiating from the questioner’s body
and the electric stimulus conducted underground to
Hans’s foot were sufficient explanation for his remark-
able 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 radi-
ate from the brain of his master; for mental work is,

ANIMAL CONSCIOUSNESS 29

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 com-
mands 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: sug-
gestion. Without defining this conception more specifi-
cally and without the slightest notion of the peculiar diffi-
culties which it involves (L. Loewenfeld in his “ Hand-
buch des Hypnotismus” [Wiesbaden, 1901, pp. 35ff.]
cites twenty different definitions of the term given by as
many authors) a critic writes: “The astounding phenom-
enon of an animal apparently possessing human reason
is to be attributed solely to suggestion”. Having re-
ferred to a dog trained for the vaudeville-stage, the gen-
tleman 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 ex-
planations? Everyone considered his own opinion the
only correct one, without, however, being able to con-
vince anyone else. The need here was not simple affirma-
tion, but proof.

CHAPTER II
EXPERIMENTS AND OBSERVATIONS
A. EXPERIMENTAL CONDITIONS

TuE observations on the horse under ordinary condi-
tions would have been quite insufficient for arriving at a
decision as to the tenability of the several possible ex-
planations. For this purpose experimentation with con-
trolled conditions was necessary.

It was necessary, first, that the place in which the
experiments were performed should be guarded against
sources of error and interruptions. Several diffi-
culties stood in the way of the removal of the horse to a
more convenient place. Therefore, a large canvas tent
was erected within the courtyard of Mr. von Osten. This
afforded the necessary isolation without hindering the
free movements of the horse. After the essential part of
the experiment had been completed and the problem had
been practically solved, experimentation was sometimes
conducted in the open courtyard. A number of the ex-
periments were also performed in the horse’s stall.

The choice of proper persons to experiment with the
horse required careful consideration. In so far as ob-
servations were to be made upon the questioner, Mr.
von Osten was of course indispensable. But to obviate
every objection he, as well as Mr. Schillings, had to be
excluded from the greater part of the experiments, and

30

EXPERIMENTS AND OBSERVATIONS | 31

other persons had to be selected who could learn to handle
the horse. Now one would have thought that the horse
would respond to any moderately efficient examiner. But
as a matter of fact it was found that the horse would not
react at all in the case of the greater number of persons.
Again, in the case of others he would respond once or
twice, but would then cease. All told, Hans responded
more or less readily to forty persons, but it was only when
he worked with Mr. von Osten or with Mr. Schillings,
that his responses were at all dependable. For this reason
I undertook to befriend the horse, and by happy chance it
came to pass in a short time he responded as readily to
my questions as to those of the two gentlemen. In a few
of these experiments the Count zu Castell, Count R. von
Matuschka and Mr. Schillings undertook the rdle of
questioner. Where these are not mentioned in the re-
sults here published, I myself did the questioning.

With regard to the number of experiments and their
performance, the following precautions were observed.
A sufficiently large number of tests was made in each
series in order to obviate the possibility of the contention
that the horse’s errors were due to chance. The condi-
tions of experimentation were such that the further con-
tention that he happened to be tired or otherwise indis-
posed, whenever the reactions seemed to be inadequate,
could not be offered. The possibility of confusing the
horse by means of unwonted conditions also had to be
avoided. For this reason it was necessary to alternate the
trial in which procedure was with the knowledge of the
answer on the part of the questioner, with the trial in
which the procedure was without such knowledge. Such
precautions had hitherto been neglected, and therefore
those negative results which had been occasionally ob-

32 THE HORSE OF MR. VON OSTEN

tained in single trials, could not claim objective validity,
even though the persons making the tests were subject-
ively convinced.

The course of the experiments was determined by the
nature of the problem itself. By means of a very simple
test it was possible to discover whether or not Hans was
able to think independently. He was confronted with
problems in which the procedure was without knowledge’
of the answer on the part of the questioner. If under’
these conditions he could respond with the correct an-
swer—which could be the result of a rational process
only—then the conclusion that he could think independ-
ently, was warranted. The examination would be closed
and Mr. von Osten would be justified in all he claimed
for the horse. If, however, Hans should fail in this test,
then the conclusion that he could think was by no means
warranted, but rather the inference that he was dependent
upon certain stimuli received from the questioner or the
environment. Further investigation would be for the pur-
pose of discovering the nature of these stimuli,

To ascertain by means of which sense organ or organs
the horse might receive these necessary stimuli, the
method of elimination was employed. We began by ex-
cluding visual stimuli by means of a pair of very large
blinders. Should this investigation be without results,
then we would proceed to test the sense of hearing. The
elimination of auditory stimulations would be more diffi-
cult, because ear-caps or the closing of the passage by
means of cotton would not give sufficient assurance that
the sound-waves were being interrupted, even if the horse
were docile enough to suffer these appliances. There-
upon would follow the testing of the sense of smell and
of the skin-senses. And finally there might be involved -

EXPERIMENTS AND OBSERVATIONS 33

another still unknown sense, such as seems to exist in the
lower animal-forms. The reader therefore can readily see
that the investigation might possibly have become very
complex, and that the investigator had to be prepared for
all of these possibilities.

The results of the experiments and the essential cir-
cumstances under which they were conducted, were in
every case recorded immediately.

It goes without saying that in the final formulation of
the results, all values—including those which were not
consonant with the majority—were to be used.

B. ExperiMENTaL RESULTS

During the course of these experiments Hans wore
his accustomed trappings, i. e., a girdle, light headgear
and snaffle, and he either stood alone, untied, or was held
loosely by the bridle either by the questioner or (though
only in a few instances) by his attendant. The ques-
tioner always stood to the right of the horse, as Mr. von
Osten had been accustomed to do. As reward for correct
responses Hans received from the questioner *—and from
him only—a bit of bread or carrot, and at times also a
square of sugar. Never was a whip applied. From time
to time the horse was led about the courtyard or was al-
lowed to run loose in order to secure the needful respite.
Besides myself there was usually present Prof. Stumpf
and Dr. von Hornbostel, who kept the records, and fre-
quently also Mr. von Osten. Several times I worked
alone with the horse. The results obtained in the horse’s
stall were in no respect different from those got in the

* The expressions guestioner and experimenter are used interchange-
ably in this treatise.

34 THE HORSE OF MR. VON OSTEN

course of the experiments carried on in the courtyard,
Whenever a doubt arose as to the number of taps made
by the horse (though this did not frequently occur), then
the series in question was immediately repeated.

In this report of the results of our experiments, the
reader must bear in mind that it was impossible to adhere
to that ordér and distribution of tests which we are wont
to require in the case of psychophysical experiments con-
ducted under regular laboratory conditions. All sorts of
difficulties had to be overcome: unfavorable weather, the
crowds of curious ones, certain peculiarities of the horse
—such as shying whenever the wind rippled the canvas
of the tent—and last but not least, the idiosyncrasies of
Mr. von Osten who repeatedly attempted to interrupt the
progress of the experiments.

Since it was evident that different kinds of processes
were involved in solving the problems and since the solu-
tions would be indicated by tapping, or by movements of
the head, or by walking over to the object to be desig-
nated, the results of these three sets of experiments have
been grouped under three corresponding heads.

I. Problems solved by tapping

The following tests were made in which the method
was such that when the problem was presented to the
horse, the correct solution was known to none of those
present, least of all to the questioner. This method we
shall designate in the following report as “ procedure
without knowledge ” whereas we shall call the method in
which the answer was known to the questioner, “ pro-
cedure with knowledge ”.

In order to discover if the horse could read numbers,

EXPERIMENTS AND OBSERVATIONS 35

a series of cards on which numerals were blazoned, were
exposed to the horse’s view in such a way that none of
those present was able to see them, and the horse was
asked to tap the numbers as they were shown. This ex-
periment was repeated at different times and in all there
were 49 tests in which procedure was without knowledge,
and 42 in which procedure was with knowledge. In the
case of the former there were 8% correct responses,
whereas in the case of the latter 98% of the answers were
right. As an example of the course which the series
tended to take, we insert the following, in which Mr. von
Osten himself acted as questioner.

Method. No, exposed. No. tapped.
Without knowledge 8 14
With 8 8
Without “ 4 8
With “ 4 4
Without se 7 9
With m 7 7
Without ss 10 17
With ae 10 fe)
Without a 3 9
With * 3 3. etc.

Whenever the questioner knew the solution, nearly all
of the horse’s answers were correct; but when the an-
swers were unknown to the questioner, the horse’s re-
sponses were, with only a few exceptions, quite unsuc-
cessful. Since the few exceptional cases must be re-
garded as fortuitous, the conclusion is warranted that the
horse was unable to read numerals without assistance.

In order to discover whether the horse could read
words such as “Hans” or “Stall” or the names
of colors, they were written upon placards and hung

30 THE HORSE OF MR. VON OSTEN

up in a row before the horse in such a way that the
questioner could see the individual word but could not
immediately recognize the particular place that each one
occupied in the series. The horse was then asked:
“Upon which placard is the word ‘ Hans’?, “On which
is the word ‘ Stall’?”, etc. In order to make sure, he
was required to repeat each answer.

Then the experimenter would determine for himself
the place of the word in the series and would ask the
question again. Fourteen such tests, in which the pro-
cedure was with knowledge on the part of the ques-
tioner, were interspersed with twelve in which the pro-
cedure was without such knowledge. With the latter
there were no correct responses, whereas in the cases of
procedure with knowledge 100% of the answers were
correct. Evidently the horse could not read words.

Three words were thereupon whispered in his ear,
which he was asked to spell in accordance with the method
described on page 21. Since he had to indicate first the
row, and then the place in the row occupied by the letter,
it took two answers to indicate the position of each letter.
I acted as questioner. The ordering of the table of let-
ters was unknown to me, except the position of the letter
“a”, which naturally came first, and the place of the
letter “s”, concerning whose position I had purposely
inquired. The words chosen for this experiment were —
“Arm”, “Rom” (Rome) and “Hans”. The horse re-
sponded incorrectly in the case of every letter which was
unknown to the questioner. “A” and “s” alone were
given correctly. Thus in spelling the word “Rom” the
horse responded with the series 3, 4; 3, 4; 5, 43.5, 4;i.e.
“jjst”, instead of the correct series: 4, 6; 4,2; 3,7. I
later selected three other words, the spelling of which in-

EXPERIMENTS AND OBSERVATIONS 37

volved the tapping of thirty-two numbers on the part of
Hans, and whose position I had carefully ascertained be-
forehand. When these were given to the horse to spell,
he responded promptly without a single error. Evidently
Hans was unable to spell without assistance of some sort
from the questioner.

The horse’s reputed aptitude in computation was tested
in the following way. Mr. von Osten whispered a num-
ber in the horse’s ear so that none of the persons present
could hear. Thereupon I did likewise. Hans was asked
to add the two. Since each of the experimenters knew
only his own number, the sum, if known to anyone, could
be known to Hans alone. Every such test was imme-
diately repeated with the result known to the experi-
menters. In 31 tests in which the method was procedure
without knowledge, 3 of the horse’s answers were correct,
whereas in the 31 tests in which the method was pro-
cedure with knowledge, 29 of his responses were correct.
Since the three correct answers in the cases in which pro-
cedure was without knowledge evidently were accidental,
the results of this series of experiments show that Hans
was unable to solve arithmetical problems.

For the purpose of discovering whether the horse could
at least count, the Russian kindergarten device, which Mr.
von Osten had used in training, was utilized. The ma-
chine was placed before the horse, but the experimenter
turned his back upon it. Before each test, a number of
balls were pushed to one side and Hans’s problem was to
indicate the number thus separated. Each test was re-
peated with procedure with knowledge. Of eight such
experiments Hans responded successfully every time pro-
cedure was with knowledge but failed every time pro-
cedure was without knowledge. Thus 7 balls were at one

38 THE HORSE OF MR. VON OSTEN

time designated as 9 and later as 14, while 6 were at first
designated as 12, and later as 10. Since all these errors
could not be accounted for on the ground of miscounts
on the part of the horse, it was evident that Hans is quite
unable to count.

The memory-test was conducted in the following man-
ner. In the absence of the questioner a number or the
name of some day of the week was spoken to the horse, ,
The experimenter would then return and question him.
Of 10 responses 2 were correct, 8 incorrect. Among the
correct answers were the number 3, a number which, as
we shall see, Hans was prone to give under all sorts of
conditions, and which therefore meant very little when
given as a correct response. The number 2, on the other
hand, was consecutively indicated by 7, 9, 5, and 3, 8 was
given as 5, 6, 4, and 6, consecutively ; and finally Wednes-
day was indicated as the fourteenth day of the week.
After this we undertook the test the horse’s far-famed
knowledge of the calendar. Dates, such as Feb. 29,
Nov. 12, etc., were given to Hans and he was asked
to indicate on which day of the week they fell. Sunday
was to be indicated by 1, Monday by 2, etc. Of 14 such
tests, IO were unsuccessful, 4 successful. But in the case
of these 4 something very interesting occurred. It hap-
pened that during this series the keeper of the horse was
present, and he happened to know the days on which
these dates fell—as he himself testified. The dates in
question were also little more than a week or so from the
day of the experiment, so they could easily be deter-
mined. But as soon as we took more remote dates both
man and beast were hopelessly lost. It was certain that
Hans had no knowledge of the calendar. It is needless
to say anything of-his supposed knowledge of cards and

EXPERIMENTS AND OBSERVATIONS 3g

coins. Hans plainly was incapable of the astonishing
_ feats of memory which had been claimed for him.

Finally we investigated Hans’ musical ability. In a
room adjoining the horse’s stall there was a small har-
monica, which spanned the once accented octave. On this
one or more tones were played. The horse was required
to indicate the tone played, the number of tones played
and their relation to one another. For testing his general
hearing 20 tests were given in which the method was pro-
cedure without knowledge. Of the responses only one
was correct, and that one was the tone e, for which the
proper response was three taps, but we must bear in mind
what has already been said of the number 3. The tone
b was indicated by 11 taps, although Hans had only
learned a scale of one octave and therefore could respond
to only seven tones. In the tests in which the method
was procedure with knowledge, he again, without excep-
tion, was successful. Similar results were obtained in the
analysis of compound clangs. In the cases of procedure
without knowledge (although the experimenter here
knew the correct responses, he purposely refrained from
thinking of them) not a single response was correct;
while in the cases of procedure with knowledge, all but
one were correct. The following were typical re-
sponses: Three tones were played and the question was
asked, “How many tones were played?” Hans re-
sponded first with 4 taps and then with 1. The tones
c, e, g, a, (1, 3, 5,6) were struck and the question asked,
“Which tone must be eliminated to make the complex a
chord?” In the tests in which the method had been
procedure with knowledge, this question had always been
answered correctly, but when procedure was without
knowledge the responses were first 13, a tone which does

40 THE HORSE OF MR. VON OSTEN

not exist for Hans, then 2, a tone which was not given
in the clang to be analyzed, and finally 3, which was not
the discordant tone. Hans’s far-famed musical ability
was an illusion.

Taking the results of all the tests into consideration,
we find that in the case of procedure with knowledge,
90 to 100% of the responses of the various series were
correct, whereas, in those series of procedure without
knowledge 10%, at most, of the responses were correct.
Under the conditions prevailing during these latter tests,
even these 10% must be regarded as due to chance. To
be sure Mr. Grabow, a member of the school board and
an enthusiastic follower of Mr. von Osten (Zeitschrift
fiir Padagogische Psychologie, Pathologie und Hygiene,
Berlin, 1904, Jahrg. 6, Heft. 6, S. 470), mentions a large
number of successful tests, which were supposedly made
in accordance with the method of procedure without
knowledge. A thorough analysis of his experiments was
not possible, because the conditions under which they
were conducted were not adequately specified. But I
have no doubt that the successful responses of the horse
were due solely to the absence of precautionary meas-
ures. I, too, could cite a number of seemingly correct
responses which demonstrably were due to the absence -
of adequate precautionary measures. I therefore repeat: ..
Hans can neither read, count nor make calculations. He
knows nothing of coins or cards, calendars or clocks, nor
can he respond, by tapping or otherwise, to a number
spoken to him but a moment before. Finally, he has not
a trace of musical ability.

After all this experimentation it was evident that the
horse was unable to work alone, but was dependent upon
certain stimuli from its environment. The question

EXPERIMENTS AND OBSERVATIONS § 41

therefore arose: does the horse get these stimuli while
the question is being put, or during his responses, i. e.,
during the process of tapping.

If Mr. von Osten’s opinion was correct, then the
process of questioning played an important part in the
success of the experiment. Of course, as he said, it was
not necessary to ask the question aloud; it was sufficient
—curiously enough—that it be inwardly spoken, thanks
to the horse’s extraordinary auditory sensitivity. If, how-
ever, conditions were made such that the auditory sense
was eliminated, then the animal would be unable to re-
spond. Such a theory is not quite as absurd as it might
seem at first blush. For Hansen and Lehmann have shown
that an acute auditory organ is able to respond to such
delicate stimulation as is involved in the softest whisper,
or even in the so-called nasal whisper in which the lips
are tightly closed They have attempted thus to ex-
plain any modes of supposed “ thought-transference ”,
(cf. page 7). Since experts on horses agree that the
horse has acute auditory sensitivity, Mr. von Osten
seized upon this fact and tried to establish his theory in
the following manner. No response was successfully
made on the part of the horse, he said, when the sound
waves caused by his (Mr. von Osten’s) inner speech were
deflected from the ear of the horse. This was the case
when he closed nose and mouth while inwardly putting
the question, or deflected the waves from the horse’s ear
by means of a placard held before his mouth while speak-
ing, or finally by applying lined ear-muffs to the horse’s
ears. If, on the other hand, he closed only his nose and
not his mouth while thus inwardly putting the question,
or if he held the placard so that there was a possibility of
deflecting the sounds to the horse’s ear, or if the ear-

42 THE HORSE OF MR. VON OSTEN

muffs were of too sheer a material, then Hans could hear
and answer the questions which for human ears were
inaudible. He demonstrated all this by means of experi-
ments and of 20 tests of the first kind, in which auditory
sensations were supposedly eliminated, 95% of the re-
sponses were incorrect (Hans would always tap too great
a number); whereas of 28 tests of the second kind, not
a single answer was wrong, just as had been predicted.
Now I have repeated both kinds of tests, but have al-
ways found some correct responses in those cases in
which the horse, supposedly, was unable to hear, a thing
which greatly astonished Mr. von Osten. In fact, the
responses of the horse were quite as correct when I did
not even whisper the question inwardly. It was quite
clear that putting the question in any form whatever was
wholly unnecessary. Mr. von Osten’s demonstrations to
the contrary, which were based upon erroneous physical
principles, are to be explained as cases of vivid auto-
suggestions, (but of this, more in Chapter V). After
all this experimentation, it was manifest that the cue was
not given to the horse while the question was being put;
it occurred, therefore, at some time during the process of
tapping. But by means of which sense organ was it
received by the horse?

We began by examining the sense of vision, and in the
following manner. Blinders were applied, and it is
worthy of mention that Hans made no attempt to resist.
The questioner stood to the right of the horse, so that
the animal knew him to be present and could hear, but
not see him. Hans was requested to tap a certain num-
ber. Then the experimenter would step forward into the
horse’s field of vision and would put the same problem
again. Since, in the tests of the first kind, Hans would

EXPERIMENTS AND OBSERVATIONS 43

‘always make the most strenuous efforts to get a view of
the questioner, and since he would rave and tear at the
lines whenever the attempt was made to tie him,—a thing
which he had never done hitherto,—it was impossible to
determine in some cases whether or not he had seen the
questioner during the process of tapping. I am using,
therefore, in the following exposition, besides the two
categories of “not seen” and “seen”, a third which I
have called “ undecided”. A total of 102 tests were made
in which large blinders were used. In 35 of these, the
experimenter certainly was “not seen” in 56 cases he
was “seen” and the remaining 11 are “undecided”.
Under the first of these categories 6% of Hans’s answers
were correct (i. e. only two), under the second head 89%
were correct and under the third 18% were right. In
other words, the horse was at a loss the moment he was
prevented from seeing the questioner; whereas his re-
sponses were nearly always correct when the experi-
menter was in sight, certain proof that the horse’s failures
are to be attributed to the elimination of visual stimuli
and not to the general inconvenience occasioned by the
blinders. It is evident therefore, that the horse required
certain visual stimuli or signs in order to make a correct
response.*

* Throughout this treatise Iam 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,‘ 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 con-
tact), which have been designed with reference to the animal’s physio-
logical 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

44 THE HORSE OF MR. VON OSTEN

Such unequivocal results, however, were only obtained
after we had provided blinders of sufficient size (15 X 15
centimeters). Mr. von Osten believing that the horse
would not suffer these to be applied, had at first proposed
other measures. He held a slate before his face. Some
of the horse’s responses were right, others wrong. The
tests were repeated and were successful as long as I, my-
self, held the slate before my face, but not a single one
of the responses was correct when another would attempt
to hold the slate before me. Mr. von Osten then brought
forth a kind of bolster which he fastened on the right
side of the horse’s face,—the side which was turned to-
ward the questioner. But this also gave uncertain re-
sults. Finally he agreed to apply blinders. But these
were much too small and projected at a great angle from
the head (Mr. von Osten had cut the straps, for he
thought they worried the animal). The result was that
only the posterior part of the horse’s normal field of vision
was obstructed. Therefore, one could never be quite
sure whether Hans, who—it will be borne in mind—made
every attempt to see the questioner, had not perhaps after
all been able to peer over the edge of the blinder. The
number of “undecided” tests, therefore, became very
great. Of 108 tests, only 25 could be placed in the

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 sit
ting 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.

EXPERIMENTS AND OBSERVATIONS 45

category of “not seen”, 44 in the “seen”, and 39, i. e.,
a third of the total, in the “ undecided.” The percentage
of correct answers for these three categories were, respec-
tively: 24%, 82% and 72%. Here we have once more
approximately the same ratio between the categories of
“seen” and “not seen” as in the case of the tests with
the smaller blinders. If we were to count the cases
which we had put under the head of “ undecided,” in the
same category as those in which vision had been ex-
cluded—as Mr. von Osten had done—then one would
have been led to the conclusion that the horse did not
need visual signs. Several observers had thus been led
astray: e. g., General Zobel writes in the “ National-
Zeitung” (Aug. 28, 1904), that upon request Mr. von
Osten had covered Hans’s right eye “ by means of some
sort of blinder, so that he was unable to see his in-
structor”’, and that Hans did not fail to respond cor-
rectly. We evidently have here to do with the unreliable
bolster mentioned above. Furthermore, Mr. Schillings
made a number of tests with the small blinders, in which
50% of the answers were correct, and probably in the
same manner were obtained the results published in one
of the daily papers (the “ Berliner Tageblatt”, Dec. 12,
1904), several days after the publication of the December
report, and reading as follows: “ Tests have been made
upon Hans with blinders over his eyes and it is to be
noted that, in spite of these, he still responds correctly.”
Mention is also made of the experiments noted in Supple-
ment III (page 257), in which Mr. von Osten hid be-
hind the questioner and merely encouraged the animal
by occasional exhortations, but it is not possible to say
with any degree of certainty in how far he was really
hidden from the horse’s view.

46 THE HORSE OF MR. VON OSTEN

I would add that the horse—in so far as it was at all
possible to decide—never looked at the persons or the ob-
jects which he was to count, or at the words which he
was to read, yet he nevertheless gave the proper responses.
But he would always make the most strenuous efforts to
see the questioner. (See page 43). I would further-
more add that several experiments, in which Mr. von
Osten and the horse were separated from each other by
means of the canvas tent, failed completely, and that, on
the other hand, all tests were successful in which the ques-
tioner was present in the feed-room and the door between
this and the horse’s stall was opened wide enough for him
to be seen by the horse. I would also mention that to-
ward evening the responses became less and less accurate.
The conclusion that visual stimuli were here operative
cannot be gainsaid.

It was possible, to be sure, that other senses might also
be involved, but it was certain that auditory sensations
did not enter it. This is shown by the fact that one might
remain just as silent while the horse was tapping his
answer as during the putting of the question and yet
obtain a correct response. Hans, furthermore, could
scarcely be distracted by auditory stimulations. If either
the experimenter or anyone else present sought, at a given
moment, to interrupt him by such calls as “ Halt”,
“Wrong”, etc., while he was going through the process
of tapping, they very seldom succeeded in their attempt.
Even though such interruption did succeed in seven out
of the twenty-one cases in which it was tried, the assump-
tion is well grounded that the success was due entirely
or almost entirely to minimal movements involuntarily
executed by those attempting the interruption. It is to
such minimal movements that the horse, as we shall

EXPERIMENTS AND OBSERVATIONS § 47

see later, promptly reacted. When the experimenter
(Piungst), himself, made the interjections, which cer-
tainly should have been more effective, we found that the
horse was actually disturbed in only two of the fourteen
cases; and finally in ten consecutive cases of attempted
interruption not a single one was successful. There was
almost a complete absence of any ear movements on the
part of the horse, a fact in which I have been borne out
by Mr. Henry Suermondt, the distinguished horseback
rider. Indeed, I cannot recall that Hans ever turned his
ears toward me, a fact which is strikingly curious in the
case of a horse so attentive and so spirited in temper.
Finally, I might also mention that the breathing of the
experimenter in no wise influenced the outcome of the
experiment. Whether he held his breath or breathed on
the leg or body of the horse, made no difference.
Investigations of the other senses became needless, for
I had, in the meantime, succeeded in discovering the es-
sential and effective signs in the course of my observa-
tions of Mr. von Osten. These signs are minimal move-
ments of the head on the part of the experimenter. As
soon as the experimenter had given a problem to the
horse, he, involuntarily, bent his head and trunk slightly
forward and the horse would then put the right foot for-
ward and begin to tap, without, however, returning it
each time to its original position. As soon as the desired
number of taps was given, the questioner would make a
slight upward jerk of the head. Thereupon the horse
would immediately swing his foot in a wide circle, bring-
ing it back to its original position. (This movement,
which in the following exposition we shall designate as
“the back step”, was never included in the count.)

48 THE HORSE OF MR. VON OSTEN

Now after Hans had ceased tapping, the questioner would
raise his head and trunk to their normal position. This
second, far coarser movement was not the signal for the
back-step, but always followed it. But whenever this
second movement was omitted, Hans, who had already
brought back his foot to the original position and had
thereby put it out of commission, as it were, would give
one more tap with his left foot.

If it was true that these movements of the questioner
guided the horse in his tapping, then the following must
be shown: First, that the same movements were observed
in Mr. von Osten in every case of successful response;
secondly, that they recurred in the same order or with
only slight individual changes in the case of all who were
able to obtain successful responses from the horse, and
that they were absent or occurred at the wrong time in
all cases of unsuccessful response. Furthermore, it was
observed that it was possible to bring about unsuccessful
reactions on the part of the horse as soon as the move-
ments were voluntarily suppressed, and conversely, that
by voluntarily giving the necessary signs the horse might
be made to respond at pleasure; so that anyone who pos-
sessed the knowledge of the proper signs could thereby
gain control over the process of response on the part of
the horse. These requirements have all been fulfilled, as
we shall see in the following pages.

With regard to the regular recurrence of the move-
ments noticed in the case of Mr. von Osten, I was, after
some practice, able to note carefully their peculiar char-
acteristics. This was rather difficult, not only on account
of their extreme minuteness, but also because that very
vivacious gentleman made sundry accompanying move-

a

EXPERIMENTS AND OBSERVATIONS 49

ments and was constantly moving back and forth. To
abstract from these the essential and really effective
movements was truly difficult. It was much easier to
observe these movements in the case of Mr. Schillings,
probably on account of the fewer accompanying move-
ments and perhaps on account of their greater distinct-
ness. Usually he would raise the entire trunk a trifle, so
that the movements could be noticed from behind. Be-
sides these, I had an opportunity to observe the Count
zu Castell, Mr. Hahn and the Count Matuschka. All
three made the same movements, though somewhat more
minutely than Mr. Schillings, yet none was as slight as
those of Mr. von Osten.* I further noticed that Count
Matuschka and Mr. Schillings often showed a tendency
to accompany every tap of the horse with a slight nod
of the head, the last being accompanied by a more pro-
nounced nod and then followed by the upward jerk of the
head, in other words, they beat time with the horse. In
the case of the last three mentioned, for whom the horse
responded far less effectively than for Mr. von Osten or
Mr. Schillings, belated or precipitate jerks would fre-
quently occur. This was found to be true in the case of
all other persons who had failed to elicit adequate re-

* 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 obser-
vation 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 watch-
ing 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.

50 THE HORSE OF MR. VON OSTEN

sponses from the horse. Often, in both cases, a com-
plete absence of any kind of minimal movement had been
noted. The accuracy of these observations in the case
of Mr. von Osten is attested by Mr. Stumpf and Mr. von
Hornbostel, and by these same gentlemen and Prof. F.
Schumann in the case of Mr. Schillings and myself.
They also found these movements to be most minute in
the case of Mr. von Osten. In my case also they pro-
nounced them “ minimal, and often quite imperceptible ”.
All other persons who have seen me work with the horse,
but who were not familiar with the nature of these move-
ments, never perceived them, no matter how closely they
observed me.

Since the doubt was expressed that these movements
did not precede but followed closely upon the back-step of
the horse (i. &, that an error with regard to the time-
element was involved), it became important that time
measurements be taken. This was done in the following
manner: The questioner asked the horse to tap numbers
from 5 to 20, seldom higher. He purposely refrained
from pronouncing the number, but recorded it after each
test had been completed. This was a matter of indiffer-
ence to the horse (see page 42), and had the advantage
that the measurement was not influenced by knowledge
on the part of the time-keeper. Two observers were
required, one watching the horse, the other the questioner.
Both observers had fifth-second stop-watches. The larger
face of this watch shows the fifth-second and a hand
on the smaller face indicates the minute. Bv pressing
upon the stem the watch may be set in motion at any
moment desired, and by pressing it once more it may
be instantly stopped, and the time elasping between

EXPERIMENTS AND OBSERVATIONS | 51

the setting in motion and the stopping may be read on the
face. By pressing upon the stem a third time the hands
are brought back to zero, and the watch is ready for
another test. At a moment agreed upon beforehand—
usually the third tap of the horse—both observers started
their watches. Practice tests had shown that this could
be done with all the accuracy necessary in this case. As
soon as the observer of the questioner noticed the latter’s
head movement he stopped his watch, and as soon as the
observer of the horse noticed the latter’s back-step he
stopped his watch. Since the movement of the horse’s
foot does not occur as a jerk, but is of greater extent than
a jerk would be, it was agreed that the observer was to
stop the watch as soon as he recognized the back-step as
such, not when the foot was being raised from the
ground, because it was not then evident whether the horse
would bring it back to the original position or whether
he was preparing to give another tap, nor when he had
brought his foot completely back, but at the moment in
which it was evident that the horse intended to make the
back-step. Experimentation had shown that an agree-
ment as to this moment was possible. A tap with the
left foot, which might possibly follow upon the back-step,
could be left out of account. The difference in time be-
tween the two watches would show the time between the
head-jerk of the questioner and the back-step of the
horse,* and if the back-step was indeed a reaction upon

* For the benefit of those who are familiar with reaction-time ex-
periments 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

52 THE HORSE OF MR. VON OSTEN

the head-jerk, then the watches would have to show a later
time for the back-step than for the head-jerk.

Measurements of this kind were taken for Mr. von
Osten, Mr. Schillings and myself. In the case of the
first two it was taken without any knowledge on their
part. They did not even know that they were being ob-
served, having been told that the measurements were for
the sake of determining the horse’s rate. In my case, to
be sure, the time could not be taken without my knowl-
edge. I succeeded, however, in eliminating the effect of
this knowledge on my part. (Cf. pages 88 and 145.)
Since the results obtained in the case of Mr. Schillings
quite agree with those obtained in my case, it is evident
they may be considered as being of equal value.

With regard to the number of tests the following table
may be referred to. The first vertical column gives the

toa 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 ob
tained 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 upona
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.

EXPERIMENTS AND OBSERVATIONS 53

name of the questioner, i. e. the person operating with
the horse. The four other columns give the number of
tests made upon each of these. The name of the person
who made the observation in each series is indicated: at
the head of the column. It is unnecessary to give the
name of the observer of the horse, for the only difficulty
lay in the observation of the questioner. The numerals
I and II indicate two series taken at different times.

v. H, Pf. Schu. St.
Questioner. I If I Il I II I Il
v. Osten............ 9 15 |. 34 17 - = 8 27
Schillings........... - =— 19 17 6 16 _-
Pfungst...... Seco 6 13 Sa Cae oS ee

We have omitted from this table several tests in which
the observer of the questioner noticed no head jerks
whatever, and therefore could not arrest his stop-watch,
although the horse responded correctly. Four tests of
this kind were made by Mr. von Hornbostel, two by Mr.
Pfungst, two by Mr. Schumann and five by Mr. Stumpf.
In the case of Mr. Pfungst the horse gave the unusually
high number of fifty taps. The attention of the observer
had been taxed too long and had failed him (two seconds
is the most favorable time). The head-jerk of Mr. von
Osten evidently occurred during a lapse in Mr. Pfungst’s
attention and therefore remained unnoticed.

54 THE HORSE OF MR. VON OSTEN

&

v. H. PE. Schu. St.

Questioner. I II I II I II I II

R. 44% 60%| 624 88%| — — 0% «=—48%
V. Osten.

Ww. 56% 20%] 12% of | — — | 100% 22%

R 100% 6924 | — — —- — |10% —
Pfungst.

Ww 0% %|/ - — - — % —

R. | — — 74% 100%] 83% 100% | —- -
Schillings.

w.|— — 5% 20%6 | 17% = =0%|—

The results of the experiments are given in the second
table. The general arrangement corresponds to that of
the first table. Even though the absolute number of tests
was small, yet for the sake of giving a better general
view, all values are given in percentages. The tests in
which the movement of the questioner had preceded that
of the horse—as had been anticipated—are recorded
under “R” (right); under “W” (wrong), we have
recorded those cases in which the testimony of the stop-
watches—contrary to our expectation—indicated that the
reverse order prevailed. Finally, those cases which would
complete the 100%, i. e. those in which the watches in-
dicate simultaneity of the movements in question, are not
recorded.

From this table we may note the following: The time-
measurements for Mr. Schillings and Mr. Pfungst are
quite in agreement and go to show that the order in time
of the head movement of the questioner and the back-

EXPERIMENTS AND OBSERVATIONS 55

step of the horse was exactly what had been expected.
The few contradictory cases which occur in Series I of
the observations upon Mr. Schillings are to be accounted
for by the fact that he was here for the first time the
subject of observation, whereas the recorded time-meas-
urements in the case of Mr. Pfungst had been preceded
by a number of practice tests. The results of the meas-
urements taken in the case of Mr. von Osten were far
less satisfactory. Even if one were to allow a series con-
taining barely more than 50% of “right” cases as suf-
ficient proof of the correctness of our expectation regard-
ing the order of the movements of the questioner and the
horse, only three of the six series obtained with Mr. von
Osten as subject, would satisfy this expectation. How-
ever, since four of the six series show a greater number
of cases of simultaneity (their percentage may be easily
deduced by referring to the per cent of “right” and
“wrong ” cases), the proposed method would give a dis-
torted view, and therefore it appears that the more cor-
rect method would be to consider simply the numerical
ratio of the “right ” and “ wrong” cases. Since, further-
more, Series II shows, in every case, a decided change
which is similar for all observers (note especially
Pfungst), there can be no doubt but that practice is here
involved, and that Series II is to be regarded as the true
standard. Throughout this series we find a preponder-
ance of “right” cases. Therefore, the table unmistaka-
bly confirms the expected order in time. That there were
more “ wrong” cases with Mr. von Osten as subject than
with the other questioners is to be explained by the fact
that the decisive movements were far less easily observed
in this case, than in that of the other questioners. (See
page 49.) We expect that Series III would show the

56 THE HORSE OF MR. VON OSTEN

same results, or approximately the same results in the
case of Mr. von Osten that it did for Mr. Pfungst and
Mr. Schillings, but unfortunately he declined to act as
subject. In the meantime, however, new and decisive
proof presented itself which destroyed all possible doubt.

Before adverting to it, let us consider in a few words
the reaction-time of the horse,—the time elapsing between
the final sign of the questioner and the reaction of the
horse (i. e., the back-step). Unfortunately this time can-
not be directly determined. All that can be ascertained
from our time-measurements, is the time intervening
between the moment of the head-jerk and the moment in
which the reaction of the horse is noted. (See page 51).
This time averaged, for the 127 measurements, .45 sec-
onds. If we stated the unavoidable error, (obtained on
the basis of extended supplementary measurements which
it is not necessary to consider here) as .15 seconds, and
apply it to the value found above, we obtain .3 seconds
as the probable reaction-time of the horse.*

That the tapping—as well as all other movements of the
horse—was nothing other than a reaction upon certain
visual stimuli, was proved beyond a doubt by the fact that
the voluntary execution of the head-jerk and of other
movements—which we will describe in more detail later
on,—brought about all the proper responses on the part of
the horse. Thus, artlficial synthesis became the test
of the correctness of analytical observation.

To elucidate; if the questioner retained the erect posi-
tion he elicited no response from the horse, say what he

* 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 But, as might have been expected,
they did not yield any satisfactory results.

EXPERIMENTS AND OBSERVATIONS | 57

would. If, however, he stooped over slightly, Hans would
immediately begin to tap, whether or not he had been
asked a question. It seems almost ridiculous that this
should never have been noticed before, but it is easily
understood, for as soon as the questioner gave the problem
he bent forward—be it ever so slightly—in order to
observe the horse’s foot the more closely, for the foot was
the horse’s organ of speech. Hans would invariably
begin to tap when I stooped to jot down some note I
wished to make. Even to lower the head a little was
sufficient to elicit a response, even though the body itself

Fic. 1.

might remain completely erect. Of thirty tests made in
this position, twenty-nine were successful. Hans would
continue to tap until the questioner again resurned a com-
pletely erect posture. If, for instance, I stooped forward
after having told the horse to tap 13, and if I purposely
remained in this position until I had counted 20, he would,
without any hesitation, tap 20. If I asked him to add 3
and 4, but did not move until 14 was reached, he would
tap 14. Twenty-six such tests gave similar results.

The reaction of the horse upon such a signal for
stopping showed slight modifications according to the

58 THE HORSE OF MR. VON OSTEN

time which elapsed between the last tap and the signal
for stopping. These modifications, which had hitherto
been paraded as expressions of the horse’s psychical power
may be illustrated by the following schematic figures
(Figures I—4). In all of them the dotted line c-d rep-
resents the ground level; d shows where the horse’s right
forefoot was located before he began tapping; a and ¢,
respectively, indicate the place to which the foot is lowered
during the process of tapping. The unbroken line gives
the direction of the back-step.

If Hans, having raised his foot from a to b—prepara-

Fic. 2.

tory to tapping,—receives the signal at or just before the
moment he lowers the foot, he immediately swings it ina
wide circle from ¢ back to its original position at d,
(Fig. 1). As a matter of fact a and ¢ coincide, but are
juxtaposed in the diagram for the sake of schematic
utility.) This was the usual form of the back-step.

If the signal for stopping is given a little after the
last tap (Fig. 2), i. e., at the time that the foot is already
being raised for another tap, then the back-step occurs
as a-b-d. The horse thus gives, at the moment it receives
the signal for stopping, a changed impulse to the moving

EXPERIMENTS AND OBSERVATIONS — 59

foot. The curve, therefore, has a kink at b, and the back-
step occurs with seeming hesitancy,—Hans appears not
quite certain of his result.

If the signal be given somewhat later still (Fig. 3), i. e.,
when the foot is being lowered to complete a tap, Hans is
still able to put on the brakes—as it were—and draw back
his foot before it reaches the ground. The whole process
gives the impression that the horse was just about to make
a “mistake” of one unit, but at the last moment had
bethought himself of the correct answer.

Finally, if the signal be deferred still longer, it becomes

Fic. 3.

impossible to prevent the extra tap. The back-step again
lias the same form as in figure 1; Hans has made a
“mistake” in his answer by one unit too many.

Conversely, if the head-jerk of the questioner occurs too
soon; i. e., at the moment the horse has raised his foot for
the final tap to the height b, (Fig. 4), then the tap is not
completed,—but the foot, without touching the ground,
‘makes the curve b c, d, back to its original position.
Hans has again made a “ mistake” in his answer,—this
time by one unit too few.

All these variations go to show one thing: Hans never

60 THE HORSE OF MR. VON OSTEN

knows in advance which tap is to be the final one. These
variations in his reactions occurred often without having
been intended by the questioner. But to bring them
about at will required skill, on account of the shortness of
the time involved in the reaction.

Whenever the signal for stopping—which we have
just discussed—was followed by the complete erection of
the head and trunk, Hans would definitely cease tapping,
If, however, the questioner failed to assume a completely
erect position, or if he stooped forward ever so slightly,
the horse would follow the back-step of the right foot

Fic. 4.

with an extra tap of the left foot. Besides occurring in
tests in which Mr. von Osten assumed the réle of ques-
tioner, this fact was also noted when the Count zu Castell
and Mr. Schillings acted as subjects. Since the extra
tap just mentioned was not given like the others with the
right foot forward, but with the left foot upon the spot,
it was possible for the horse to execute it with a greater
show of energy. This simulated a high degree of mental
certainty on the part of the horse, as if he wished to
indicate that this was the correct solution of the problem
and it would have to stand. In spite of all this, many

EXPERIMENTS AND OBSERVATIONS | 61

errors would creep in. It was possible to prolong this
extra tap and thus make it appear more dilatory. We
need hardly add that henceforth it was within the power
of the experimenter to have the tapping executed entirely
with the right foot or with the final extra tap of the left
foot. Hitherto the view had been current that this lay
solely within the pleasure of the horse.

If the questioner still inclined forward, still remained
in the bent posture after Hans had given the final tap
with his left foot, the horse would immediately begin to
tap once more with his right foot, which had, in the mean-
time, become ready for further action. If the head jerk
was then made, Hans would bring his right foot back,
give the extra tap with his left foot, then resume tapping
with the right and thus continue until the questioner once
more resumed the erect posture. Thus the horse on one
occasion when I wished him to tap 100, gave—contrary
.to my desire—the following response; 39 with the right
foot, I with the left, 24 with the right, 1 with the left, 35
with the right, and 1 with the left. Later it became
possible for me to cause him to tap 1 right, 1 left, 1 right,
I left, etc. I could even get him to tap exclusively with
the left foot by standing at his left rather than at his right
as had been customary with his questioners. These taps
with the left foot were executed in a far less elegant
fashion than those with the right foot, and with a great
waste of energy. Hans had become a right-handed
individual—as it were—as a result of long habit.

With regard to the distance at which the experimenter
directed the horse, the following may be said: The usual
distance was one-quarter to one-half meter. This holds
for all tests hitherto described. Seventy tests which were
made for the purpose of discovering the influence of

62 THE HORSE OF MR. VON OSTEN

change in distance showed that the reaction of the horse
upon the customary signal of the head-jerk was accurate
up to a distance of three and one-half meters. At a
distance of three and one-half to four meters there sud-
denly occurred a fall of 60-70% in the number of correct
responses. At a distance of four to four and one-half
meters only one-third of the responses were correct, and
at a distance beyond four and one-half meters there were
no correct responses. The greater number of these tests
were made in our presence by Mr. von Osten, who was
under the impression that we were testing the accuracy of
the horse’s hearing, whereas we were really testing the
accuracy of his perception of movements.

With regard to the different positions which the experi-
menter might assume with reference to the horse, the
following may be noted: The normal position was to the
right of the horse. If the experimenter stood immediately
in front of Hans, the latter’s reaction would be just as
accurate, though he would always turn his head and
make desperate efforts to see the questioner, even though
he was held in short by the reins. When a position im-
mediately behind the horse was taken—a somewhat
dangerous proceeding, since Hans would at once begin
to kick—no response could be obtained until he succeeded
in turning far enough around to get the questioner within
view. If he was restrained from turning completely
around, he would at least turn his head,—and always to
the right. One might even turn his back upon Hans
during the tests, for the signal for stopping was not
obtained from the face of the questioner, but from a move-
‘ment of the head. The following incident will show to
what extent the horse had become accustomed to seeing
the questioner in a certain definite position. For a long

EXPERIMENTS AND OBSERVATIONS 63

time I had been in the habit—without exception—of
standing close to the horse’s shoulder. Mr. von Osten,
on the other hand, would stand farther back. When, on a
certain day, I assumed the latter position, the horse would
not suffer it, but would move backward until he had his
accustomed view of me.

Finally we sought to discover by what movements the
horse could be made to cease tapping. We discovered
that upward movements served as signals for stopping.
The raising of the head was the most effective, though
the raising of the eyebrows, or the dilation of the nostrils
—as in a sneer—seemed also to be efficacious. However,
it was impossible for me to discover whether or not these
latter movements were accompanied by some slight,
involuntary upward movement of the head. The upward
movement of the head was ineffective only when it did not
occur as a jerk, but was executed in a circuitous form,—
first upward and then back again. Such a movement was
occasionally observed in the case of Mr. von Osten. The
elevation of the arms or of the elbow nearest the horse, or
the elevation of the entire body was also effective. Even
if a placard, with which the experimenter tried to cover
his face, were raised at a given moment, the horse would
make the back-step. On the other hand, head movements
to the right and to the left or forward and back, in fine,
all horizontal movements, remained ineffective. We also
found that all hand movements, including the “ wonder-
fully effective thrust of the hand into the pocket filled with
carrots”, brought no response. I might also change my
position and walk forward and then backward some dis-
tance behind the horse, but the back-step would only occur
in response to the characteristic stimulus. After what
has been said it is easy to understand how vain were Mr.

64 THE HORSE OF MR. VON OSTEN

Schillings’ attempts to disturb the horse and how naturally
he might conclude that Hans was not influenced by visual
signs. Mr. Schillings simply did not know which signs
were effective.

While the horse could thus be interrupted in the process
of tapping by movements which were executed at the
level of the questioner’s head, yet movements below this
level had the opposite effect. If Hans showed that he
was about to cease tapping before it was desired, it was
possible to cause him to continue by simply bending for-
ward a trifle more. The greater angle at which the
questioner’s trunk was now inclined caused the horse to
increase the rate of tapping. The rule may be stated
thus: The greater the angle at which the body inclined
forward, the greater the horse’s rate of tapping, and vice
versa, It was noticeable that whenever Mr. von Osten
asked for a relatively large number—in which case he
always bent farther forward than in the case of smaller
numbers—Hans would immediately begin to tap very
swiftly. Not being entirely satisfied with these observa-
tions, the following more exact measurements were taken,
I asked the horse to tap 20. From 1 to 10 I held my body
at a certain constant angle, at 10 I suddenly bent farther
forward and retained this posture until 20 had been
reached. If there existed a relationship between the angle
of inclination and the rate of tapping, then the time for
the last ten taps ought to be less than for the first ten.
Of 34 such tests 31 were sucessful. The following are
two specimen series.

The first series consisted of ten tests of 1 5 taps each.
In all cases my head was bent at an angle of 30° to the
axis of the trunk, but I constantly changed the angle of
inclination of the trunk. It was not possible to measure

EXPERIMENTS AND OBSERVATIONS _ 65

this angle accurately on account of the rapidity with
which the whole test had to be made. I was able, how-
ever, to differentiate between them with enough accuracy
to designate the smallest angle (about 20°) as belonging
to Grade I, and the greatest angle (about 100°) as belong-
ing to Grade VII. By fixing certain points in the environ-
ment, it was possible to get approximately the same angle
repeatedly. The time from the third to the thirteenth tap
was, in all cases, taken by Prof. Stumpf by means of a
stop-watch. The tests were taken in the following
order:

Grade of inclination: I VI JI II IV V_ VI VII
Time for Io taps: 52 46 50 50 48 48 4.6 4.4 sec.

From this series it will be seen that in the case of the
same angle of inclination (II and VI were repeated and
III was omitted) the same rate obtained in the tapping.
In two other tests I constantly increased the angle of
inclination during the 15 taps, and Hans gradually
increased the rate of tapping accordingly.

In a second series I had the horse tap 14, five times.
I myself took the time of the taps up to 7 by means of the
stop-watch, while Prof. Stumpf took the time of the taps
from 8 to 13. At 8I suddenly bent forward a little more
and retained this position until tap 13. The results were
as follows:

Taps 2to7 (Pf.): 3.2 2.2-2.4 2.4 2.2-2.4 2.4 seconds.
“ 8to13(St): 26 20 20 22 2.2 seconds.

Such good results, however, were possible only after
a number of preliminary practice tests had been made.
The experiment was especially difficult because the horse
was often on the point of stopping in the midst of a test.
This was probably due to some unintentional movement

66 THE HORSE OF MR. VON OSTEN

on my part. In such cases I could induce him to con-
tinue tapping only by bending forward still more, but this
effected also, as we have seen, an increase in his rate
of tapping. Such tests, of course, could not give
unambiguous results.

The rate of tapping was quite independent of my rate
of counting. Thus, if I counted aloud rapidly, but bent
forward only very slightly, the horse’s tapping was slow
and lagged behind my count. If I counted slowly but
bent far forward, Hans would tap rapidly and advance
beyond my count. Thus we see that his rate of tapping
was in accordance with the degree of inclination of my
body and never in accordance with the rate of my count-
ing, i. e., it was quite independent of every sort of auditory
stimulation.

Direct observation and a comparison of the records of
the time Hans required in giving to his master responses
involving small, medium and large numbers, with the
records of the time which he required to respond to my
questions when I bent only slightly, moderately or very
far forward, proved that the increased rapidity in tapping
in the case of large numbers, which many regarded as an
evidence of high intelligence, (see page 20), was, as a
matter of fact, brought about in the way described. The
two series (in each of which the time measured was for
Io taps) are quite in accord. The horse did not tap
faster because he had been given a large number by Mr.
von Osten, but because the latter had bent farther for-
ward.

From all this it readily appears why it was possible to
cause Hans to increase his rate of tapping but not to
decrease it. To do the latter would involve a decrease in
the angle of inclination of the body. This would neces-

EXPERIMENTS AND OBSERVATIONS 67

sitate the erection of the body. As we have seen, this
was the signal to which Hans reacted by ceasing to tap.
And as a matter of fact we never knew the horse to
decrease his rate of tapping in the course of any single
test, except in the case of very large numbers, and then
it was probably due to fatigue. Mr. von Osten insisted
that Hans often slowed down toward the end of a test,
“in order to obviate mistakes ”’, but all the tests in which
he tried to demonstrate this to us, were unsuccessful. In
spite of all exhortation, Hans would tap either uniformly
or somewhat more rapidly as soon as his master—in all
probability unconsciously—bent somewhat lower. Only
once was such a test successful. Mr. von Osten—upon
our request—asked the horse to give a certain large
number. In this instance the decrease in the rate of
tapping was due to fatigue and had nothing whatever
to do with the desire on the part of the horse to avoid
error. Futhermore, Mr. Hahn, who had visited Hans
twenty times and had made careful notes of his observa-
tions, corroborated my statement when he said that he
himself never noted the decrease in rate mentioned. Con-
trary statements may perhaps be due to the fact that the
tense state of expectancy on the part of the observer made
the interval between the last taps appear subjectively
somewhat longer.

So much for the technique of the tapping. Now a
word about the numbers which Hans tapped. (I refer
only to the results obtained in series which involved no
volitional control). The number 1 was very difficult to
get. Hans usually tapped 2 instead. Thus even in the
case of Mr. von Osten he responded five times with 2,
and only in the sixth test did he react correctly. As far
as other questioners were concerned, 1 was seldom ever

68 THE HORSE OF MR. VON OSTEN

obtained, except in the case of Mr. Schillings and myself.
The numbers 2, 3 and 4, on the other hand, were very
easily obtained and, above all, 3 seldom failed. 3 seemed
to be the horse’s favorite number and was very frequently
given instead of other numbers. Thus, one-sixth of all
the horse’s incorrect responses which were given to me
were in terms of the number 3. The numbers 5 and 6 were
a little more difficult to obtain and above Io the difficulty
increased rapidly. Indeed, I never saw Hans respond
with a number exceeding 20 to any questioner, Mr.
Schillings and Mr. von Osten excepted. I saw the nine
vain attempts of Count zu Castell to get the number 15,
and Count Matuschka’s eight unsuccessful attempts to
obtain the number 16 as a response. But even with Mr.
von Osten and Mr. Schillings such failures were not
infrequent. Thus, Mr. von Osten tried five consecutive
times to obtain the number 24. I myself did not fare
any better at first. But the following table shows what
practice can do. If we compare the percentage of correct
responses (involving the numbers 1 to 7—for which alone
I have sufficient material, viz., 80 to 100 cases), obtained
in the first half of our tests, with that of the second half,
we get the following:

For number: I 2 3 4 § 6 7
In first half of tests: 49, 92, 89, 86, 74, 62, 53%
“second “ “92, 95 92, 98, 97, 86, 96%

From this we see how hard it was at first to get the
number I and that failure was as frequent as success, and
how much easier it was on the other hand to get the
numbers 2 and 3 (and which, therefore, do not show any
great improvement in the second half of the tests).
Beyond the 3 the percentage of correct responses de-
creased and the number 7 stood at the same level as the

EXPERIMENTS AND OBSERVATIONS 69

number 1. In the second half of the tests, all these
differences disappeared and errors were infrequent and
seldom exceeded + 1 or—z1. These results of practice are
not to be accredited to the horse, but to the experimenter,
who was at first quite unskilled. This difference in results
does not appear in the case of Mr. von Osten, for his.
initial practice had been had many years previous. The
values obtained in his case were very constant throughout
our experimentation and generally showed something like
90% of correct responses. To be sure, in his case also,
the number I was somewhat unfavorable, (79% were
correct responses). But the percentages obtained in his
case showed no improvement whatever throughout our
experimentation. We need scarcely add that with the
voluntary control of the giving of the signs, in the case at
least of such small numbers as are here discussed, no
errors, whatever, occurred.

We have discussed the influence of the experimenter,
i. e., the one who asked the horse to tap; now let us con-
sider the influence of others present upon the horse.

As a general rule, other persons had no effect upon the
horse’s responses. This appears from the failure of nearly
all tests in which all of those present—with the exception
of the questioner himself—knew the number which the
horse was to tap. Even when the others concentrated
their whole attention upon the number, it profited little as
a close analysis of the 136 cases, which belong under this
head in our records, go to prove. Thus, in the presence
of a group of twenty interested persons—during the
absence of Mr. von Osten—twenty-one problems were
given to the horse, the solutions of which were known to
everyone but myself, the questioner. Result: only two
correct responses. Only when there was among the

70 THE HORSE OF MR. VON OSTEN

spectators someone to whom the horse was accustomed to
respond or one from whom he regularly received his. food,
would such an influence be effective.* But such cases

* 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 wcre made under the following conditions: The
horse was standing in his stall, when Mr. Schillings and another gentle
man 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.

I later tried similar experiments together with Mr. Hahn. I was
aware of the answer to the riddle at the time, but he was not. Mr.
Hahn stepped in front of the horse and thought intently of certain
numbers. I did the questioning, that is, I got the horse to tap. In
twelve tests Hans responded correctly in only two instances. In the
ten others he always tapped beyond the number Mr. Hahn had in
mind, e.g., 21 instead of 2, and was evidently awaiting a movement on
my part. When we exchanged rdles, Mr. Hahn doing the questioning
and I doing the “ thinking,” the horse would not respond at all, although
as a rule Mr, Hahn had been fairly successful in working with him
alone. Ihad gradually gained so much influence over the horse, that
he would scarcely attend to any one else when I was about—Mr. von
Osten hardly excepted.

In this connection I would prefer to avoid the term “ rapport,” which
may rise in the minds of many, since it has been used so much in con
nection with the phenomena of hypnotism, for I would not obscure a
fact that is clear by giving it a name that is vague.

EXPERIMENTS AND OBSERVATIONS 71

were few. The most important were the following:
I at one time whispered a number to Hans (on the occa-
sion of the tests mentioned on page 37), and Mr. von
Osten asked for it the moment I stepped aside. Hans
answered incorrectly even though I stood close beside
Mr. von Osten; I did not, however, think intently of the
number. As soon as I concentrated my attention upon
the number he promptly responded correctly. Further
cases are those mentioned on page 38, in which the
keeper of the horse unintentionally aided in giving four
dates which were unknown to all others present, including
the questioner. This single instance shows the necessity
of the rule that during tests in which the method is that
of procedure without knowledge the solutions should be
known to no one of those present. Finally the tests made
by the September-Commission and reported in Supple-
ment III (page 255) may possibly belong under this head.
Since they were not followed out any further, I am unable
to render a definite judgment upon them. In most of
these tests the question itself, as put by Mr. von Osten,
was not adequately answered, but curiously enough, how-
ever, the number which had been given to Hans in von
Osten’s absence and which formed the initial number of
some mathematical operation, was tapped correctly. This
may possibly be explained by the assumption that this
initial number had been retained in the memory of some
of those present, (see page 149, on the “ perseverative
tendency ”), and that the horse, since he had been working
with some of them, responded to one of those present.
Chance may have played some part also.

If the questioner knew the number of taps desired,
(which was not the case with the tests hitherto discussed),
then the environment had still less influence upon the

72 THE HORSE OF MR. VON OSTEN

horse—except that it caused occasional interruption. The
horse’s responses, therefore, did not tend to become more
successful just because a number of persons were
simultaneously concentrating upon the result desired,
This was proven by the experiments which we repeatedly
made for this purpose. Only one person at a time had
any influence upon Hans. If two questioners tried to in-
fluence the horse at the same time,—other conditions being
the same,—success would be for the one who had the
greater control over the animal when working alone with
him. Prof. Stumpf and I made the following experiment.
Both of us stood to the right of the horse, each thinking
of a number. In ten such tests Hans always tapped my
number. When Stumpf concentrated upon 5 and I upon
8, the horse responded with 8, i. e., the larger number.
When Stumpf had 7 in mind, and I had 4, the response
would be 4, i. e., the smaller number. When Stumpf
thought of number 6, and I had fixed upon none, Hans
tapped 35. He was evidently awaiting my signal. When
I went away Stumpf again demanded the number 6, and
the horse responded properly. When I returned, Stumpf’s
attempts again failed. On another occasion Count
Matuschka put a number of questions, while Mr. von
Osten stood behind him. All of the horse’s responses
were correct, even the one answering the question:
“How much is 7 times 7?”, which was difficult on
account of the great number of taps required. I was
able to note from the direction of the horse’s eyes that he
was attending only to his master and not to the Count.
On still another occasion Mr. Grabow sang two tones—
the second being the fourth of the first—and asked Hans:
“How many intervals lie between?” I was standing
erect before the horse, and was thinking intently of the

EXPERIMENTS AND OBSERVATIONS 73

number 2, but without giving any voluntary sign of any
sort. Hans tapped 2, whereupon Mr. Grabow put a
number of similar questions; but I no longer thought of
the answers, and all of Hans’s responses went wrong.
Although Hans was not influenced by others so long as
a suitable experimenter was present, yet he might be
disturbed and under certain conditions might be led to
make the back-step in response to certain movements in
his environment. The person to whom he responded
would have to be close to the experimenter and would
necessarily have to execute a movement greater in extent
than the experimenter’s. In such instances the raising of
the head, arm or trunk, was a sufficient stimulus. Thus
we made the following two series of tests. Mr.-Stumpf
stood with trunk bent forward before the horse, and at
a moment decided upon beforehand, assumed an erect
position. I myself stood beside Hans and asked him to
tap. When I stood at the horse’s neck, then Mr. Stumpf’s
interruption was effective. When I stood at the horse’s
flank, the interruption effected only a seeming hesitation,
and when I moved still farther back, the horse continued
to tap despite any attempted disturbance. In the second
series the questioner remained constantly at the right
shoulder of the horse, while the one who attempted to dis-
tract him, changed positions. When the latter stood to
the right immediately in front of or beside the questioner,
the distrubance was effective in Io out of 13 cases. But
when he stood back of, and to the right of, the questioner,
the attempts at disturbance were seldom successful. If
he chose a place before and to the left of the horse, there
was hardly any distraction (in 4 cases only, out of 13),
and if he stood to the left and behind the animal, he
exerted no influence whatever. Hans manifestly turned

74 THE HORSE OF MR. VON OSTEN

his attention, almost exclusively, to the side at which the
questioner stood.

That knowledge of this modus operandi made it
possible for those persons to get responses from the
horse, who hitherto had been unsuccessful, is shown in
the case of Mr. Stumpf when he began to control his
movements voluntarily on the basis of observations which
had been made.

II. Problems which Hans solved by movements of the
head.

We are here concerned with the horse’s head move-
ments upward, downward, to the right and to the left,
and also with nodding and shaking of the head to signify
“yes” and “no”. We soon discovered that these ex-
periments, also, were successful without an oral state-
ment of the problem,—in other words, the auditory
stimulus was quite superfluous. The tests with the
blinders showed that Hans was lost as soon as his ques-
tioner was out of his view, but responded adequately the
moment the questioner was in sight. Hans, therefore,
had established no idea of any sort in connection with
the terms “up”, “down”, etc., but in these cases, like-
wise, he reacted in response to certain visual stimuli. The
nature of these stimuli I discovered at first in my observa-
tions of Mr. von Osten and also of myself, when working
with the horse.

Above all things it was necessary that the questioner,
during these tests, should stand perfectly erect. If he
stooped ever so slightly, the test was unsuccessful. If he
carefully refrained from any movement whatsoever, and
looking straight before him asked the horse, “ Which

EXPERIMENTS AND OBSERVATIONS = 75

direction is right?” or “ Which way is upward?”, Hans
would execute all sorts of head movements without rhyme
orreason. It was evident that he noted that a head move-
ment of some kind was expected of him, but did not know
the particular one that was wanted. But if the questioner
now raised his head, Hans would begin to nod and would
continue doing so until the questioner lowered his head.
This reaction was interpreted as signifying “yes”. Mr.
von Osten had always asked Hans before each of the
more difficult tests whether he had comprehended the
meaning of the problem, and was reassured only upon
seeing the horse’s affirmative response. But contrary to
Mr. von Osten’s expectation, Hans also responded in this
manner after a pair of ear-caps had been drawn over his
ears. In the case of the tests described at the beginning
of the chapter, in which the method was that of “ pro-
cedure without knowledge”, Mr. von Osten had always
insisted that we await Hans’s nod of comprehension
before proceeding. We complied; Hans nodded and—
regularly disgraced himself!

When the questioner raised his head somewhat higher
than normal, Hans would throw his own upward, which
was supposed to signify “ upward”. A lowering of the
head on the part of the questioner was followed by a
lowering on the part of Hans, which was his form of re-
sponse for “down”. For some time I was in a quandary
as to the difference between the questioner’s signal for
this latter response and the one which was the signal for
the horse to begin tapping, although I had often given
both kinds unwittingly. Further experiments showed
that Hans responded with a nod of the head whenever
the questioner, while bending forward, chanced to stand
in front of, or to the side of the horse’s head, but that

76 THE HORSE OF MR. VON OSTEN

he would begin to tap in response to the same signal,
as soon as the experimenter stood farther back. The
difference in the two signals, therefore, was very slight,
and I repeatedly noted that instead of tapping, as he had
been requested, Hans would respond to the Count zu
Castell’s and Mr. Schillings’ questions by a nod of the
head.

If, while standing in the customary position to the
right of and facing the horse, the questioner would turn
his head a little to the right—a movement which, when
seen from the horse’s position, would appear to be to the
left,—Hans would turn his head to his left. But if on
the other hand the questioner would turn slightly to the
left,—i. e. seen from the horse’s position, to the right,—
then Hans would turn his head to his right. And finally,
whenever the questioner turned his head first to the right,
then to the left, Hans would respond by turning first to
his left, then to his right. This, according to Mr. von
Osten, signified “zero” or “no”. Since this movement
could not be executed by the experimenter while in a
stooping position, it can now readily be seen why it was
that Hans, instead of shaking his head, always began to
tap whenever a placard with “O” upon it, was shown to
him in the course of the experiments in which the
method was procedure without knowledge on the part of
the questioner. The latter expected the horse to tap, and
therefore bent forward. Like all of the horse’s other forms
of response, this, too, was always unsuccessful when-
ever the questioner stepped behind the animal. Although
Hans had always responded to Mr. von Osten and Mr.
Schillings, and at first also to me, by means of the
stereotyped movement of the head to the right and then
to the left to signify “zero” or “no”, I later succeeded

EXPERIMENTS AND OBSERVATIONS 77

in controlling my signals so as to get the inverted order
in the horse’s response. In the case of Mr. Schillings and
of Mr. von Osten all of the movements just described
were very minute, and long after the movements, which
were effective stimuli for releasing the process of tapping,
were recognized, it was still exceedingly difficult to dis-
cover them in these two gentlemen. The signal for
“zero” and “no” was relatively the most pronounced of
the group in the case of Mr. von Osten, while with Mr.
Schillings it was the least pronounced, in comparison with
his very strong “jerk”. Yet in both cases Hans re-
sponded wtih absolute certainty.

It is now readily conceivable how it was possible to
make the horse respond to all sorts of foolish questions,
both by involuntary signs—i. e., expressions following
upon the bare imaging of the response expected,—as well
as by means of controlled signs. One could thus obtain
consecutively the answers “ yes” and ‘‘no” to the same
question. Or one might ask: “ Hans, where is your
head?”, and Hans would bend to the earth. “And
where are your legs?” He would look at the skies. Etc.

Let us examine for a moment the directives which the
horse required for the various positions. If one called
him, while he was running about the courtyard, he paid
no attention whatever, but if one beckoned to him, he
came immediately. A raising of the hand brought him
to a standstill. If one now stepped forward or pointed
one’s hand in that direction, he would step forward, or
vice versa, he would step backward. By means of mini-
mal movements of the head, of the arm nearest the
horse, or of the whole body, Hans could be induced to
assume the position one desired, without touching him or
speaking a word. I noticed this quite early in the course

78 THE HORSE OF MR. VON OSTEN

of the investigation. Once, when intending to ask the
horse to step backward to the right, I inadvertently said
“Step backward to the left!”, whereupon he stepped
backward to the right. In spite of my verbal error, I had
involuntarily given him the proper directives.

Finally we may note that Mr. von Osten had occa-
sionally asked the horse to jump or to rear. The com-
mand in this case was: “ Jump”, or the question was:
“What do the horses do in the circus?’’. Since these
tests were just as effective when the command was given
silently, it was an indication that these, too, depended
upon visual stimuli. What was necessary to cause the
horse to step backward and then jump forward was to
step backward oneself, or make a slight movement of the
hand in that direction. If one wished to make him rear,
it might be effected by throwing the arm or head slightly
upward.

III, Problems, which Hans solved by approaching the
objects to be designated.

The method pursued in these tests was the following:
From five to eight pieces of colored cloth 44% meters in
size were arranged in changing series upon the ground,
the interval between them being equal to the width of
one piece, or else they were hung upon a string a man’s
height above the ground. This method was also employed
when placards of like size with written symbols were
used. The horse stood ten paces away and opposite the
middle of the series, while Mr. von Osten stood at his
right. Hans was asked to go and point out the cloth of
a certain color or the placard with a certain word upon it. |
If the cloth lay upon the ground, Hans picked it up with

EXPERIMENTS AND OBSERVATIONS = 79

his mouth and carried it to the questioner. If the cloth,
like the placards, hung from the cord, he approached,
pointed it out with his nose and then backed up to his
original position. Before approaching the objects, Hans
was required to indicate, by tapping, the number of the
place in the series (counting from left to right), which
the cloth or placard occupied. Mr. von Osten never
omitted this requirement. Then the command “Go!”
was given, and Hans obeyed. (As a matter of fact, a
slight directive movement of the head or hand was just
as effective as the spoken command).

The following cases, chosen in a haphazard fashion,
show that the horse’s indication of the object’s place in
the series, by means of tapping, was by no means a
guarantee that he would point it out correctly. Five
placards hung from the cord. Mr. von Osten asked:
“What is the position, counting from left to right, of the
placard which has the word ‘aber’ inscribed upon it?”.
Hans answered: 3. (It was indeed the middle placard.)
Then he was commanded: “Go!”. Thereupon Hans
went straight to the fourth placard. On another occa-
sion Hans happened to drop a brown cloth upon a black
one. His master asked him: “In which place are there
two cloths?”. Hans responded correctly, “ In the second
place”. To the question “ Which of the two is the black
one?” he also answered rightly: “The lower one”.
Upon being asked to get it, he brought the white cloth.

The large number and the irregularities of the errors
showed that there was no manner of intelligence involved
in the pointing out process. Thus during the two months
of our experimentation Hans was asked twenty-five times
by Mr. von Osten to bring the green cloth. Only six
times did he succeed in the first attempt, while in five

80 THE HORSE OF MR. VON OSTEN

instances he selected an orange-colored cloth, four times
a blue, three times a white one.

The fact that the errors were equally distributed over
the tests with the colored cloths and those with the
placards is strong evidence that the horse’s response
involved no intellectual process, for if that were the case,
then the responses in the tests with the placards would
have been very much more difficult, for they would have
involved the ability to read, whereas the tests with the
colored cloths demanded only that a few names be
remembered. Nevertheless, the horse was as unsuccess-
ful in tests of one kind as he was in those of the other,
—even when Mr. von Osten acted as questioner. (50%
failures in 78 placard tests; 46% failures in 103 color
tests. )

The fact that commands which were purposely
enunciated poorly, or else not spoken at all, were executed
with just as much accuracy as those given aloud,
strengthened us in our supposition. On one occasion
I placed a blank placard with the others. When I
ordered him to approach tabula rasa, he invariably
went to the right one. The following illustrates how he
fulfilled quite nonsensical commands. A series of blue
and green cloths lay upon the ground. Being asked
where the black, the orange, and the yellow cloths lay,
Hans shook his head energetically, i. e. they were not
there. And yet, upon being asked to bring them in the
order named, he regularly brought one of the blue ones.

All this goes to show that Hans did not know the
names of the colors (to say nothing of the symbols on the
placards). It was plain that here also, as in all the
other cases, he was controlled by signs made by the
questioner, the nature of which I soon discovered. Stand=

EXPERIMENTS AND OBSERVATIONS 81

ing erect, Mr. von Osten always turned head and trunk
in the direction of the cloth or placard desired. Hans,
keeping his eye on his master, would proceed in that
direction. Even after he had already started out, thanks
to his large visual field one could control his direction by
turning slightly more to the right or to the left. If,
however, he had already arrived at the row of placards or
- cloths, this method ceased to be effective, for then he
could no longer see the experimenter. It made no dif-
ference whether the cloths lay on the ground, or were
suspended, like the placards.

The following fact justifies the conclusion that the
bodily attitude of the questioner was the effective signal.
The more numerous the cloths, or the nearer they were
placed together, the more difficult one would expect it to
be for the horse to select the one indicated by the experi-
menter. Such was indeed the case, for the number of
errors increased with the number of cloths presented.

But no matter how many cloths there might be, or how
closely they might be placed, it was always possible to
indicate either end of the row, for in that case one had
merely to turn to the extreme left or the extreme right,
and might even turn beyond the row. Hans seldom
failed in these cases, whereas he made many errors when
cloths or placards within the series were wanted.

To turn from the nature and number of Hans’s errors,
to their distribution,—observation proved the hypothesis
that the nearer two cloths lay together, the greater was
the chance of their being mistaken one for the other.
If we designate as “error 1” all those cases in which
Hans went to cloth II instead of to cloth I, cloth III
instead of cloth II, to V instead of IV, etc., and as “ error
2”. when’he mistook III for I, IV for II, in fine, when-

82 THE HORSE OF MR. VON OSTEN

ever he went two places too far to the right or left, and as
“error 3” whenever he went three places too far to
either side of the cloth desired, we find the following
grouping of errors:

With Mr. von Osten, a total of 63 errors,:

TZ G weve secersenvees “ error y

BES cesciwic dente “SS ICROn2!”
AED eater ctesatanaencveneksiots “ error 3”
TG. spc veriycasdanpenceveuete “ error 4”
BOD eecsincisiteactomoren atin “ error 5”

With Mr. Pfungst, a total of 64 errors,;

OBEG citasesessirich enienotiuerer “ error1”

DONT: Sati wdatesisn naiencnonensearea “ error 2”
1 Ce “ error 3”
Bcc vsverincaveoes usucvevivessct “ error 4”
ORG sorsiatevers veseuaintvevaens “ errors”.

The most frequently recurring error, therefore, was the
one in which the horse, instead of going to the cloth
desired, approached the one immediately adjacent. On
page 79 I said that Hans’s errors were without system,
but only in so far as it was impossible to explain them on
a basis of the colors which seemingly were mistaken one
for the other. A part of a series in which Mr. von Osten
acted as questioner may serve as an illustration. The
order given is that of the experimental series as it
occurred. Five colored cloths were used.

Color of the cloth
asked for: blue, brown, brown, brown, brown, brown, green, green.

brought: orange, orange, green, green, yellow, green, blue, orange.

Place of cloth
asked for: V II II II II II III Il

| | | | | | ae
brought: IV IV WI WZ I imwé Vv Iv

EXPERIMENTS AND OBSERVATIONS 83

The interpretation of this series which it would be hard
to explain by a reference to the colors which were mis-
taken, is simply this: Cloths lying near together were
regularly mistaken on the part of the horse.

Experimental control of the questioner’s movements
decided the question. If the questioner at first indicated
the proper direction and then turned about after the
horse had already started forward, he was as a rule mis-
led. When the questioner did not face the cloths at all,
but turned away at right angles, or when he turned his
back upon them, Hans was completely at sea. If, on
the other hand, the cloths were arranged, not in a row,
but in several heaps, so that one might turn to a particular
heap, but could not indicate a particular cloth, then Hans
would regularly go to the proper heap, but would always
bring forth the wrong cloth. After much persuasion Mr.
von Osten consented to make a series of these tests him-
self. Hans’s failures were deplorable. He would take
up first one cloth then another, turn again to the first, etc.
We would mention, however, that this apparent searching
was not done spontaneously, but in reponse to Mr. von
Osten’s calls, such as “ See there! ”, “ The blue!”, etc.
Every time Mr. von Osten called, Hans would drop the
cloth he was holding in his mouth, or he would turn away
from the one he was about to grasp, and would then try
another one,

In addition to these visual signs, the horse received
auditory signals in these tests, (as in all others in which
he was required to bring objects). As soon as the ques-
tioner noticed that Hans was about to take up the wrong
cloth, all that was necessary to make him correct his error
was to give some sort of an. exclamation, such as
“Wrong! ”, “Look, you!”, “ Blue!”, etc. Hans would

84 THE HORSE OF MR. VON OSTEN

pass on as long as the calling continued. If he was pick-
ing up, or about to pick up, a cloth when the exclamation
was made, he would go on to the next; but if, at the time
he was on his way to a certain cloth, he would change his
direction in response to the call. If he stood before one
of the pieces at the time, but had not lowered his head, he
would pass on to the next. In all this he would adhere
to a certain routine of procedure. If he was approaching
a series from the right, then a call would cause him to
turn to the left, if he was coming from the left, he would
turn to the right. If he had approached the row of
cloths near the center, he would turn, in response to the
questioner’s calls, to the left,—seldom, very seldom, to the
right. Mr. von Osten did not seem to be able to control
the responses of the horse, entirely. As a rule, but not
always, one call sufficed to make Hans pass on to the next
cloth. If too many calls were given, he would often go
too far. Loud exclamations were superfluous.

These statements are not mere assertions, but are
founded upon the records of the results. The tests in
which calls were made show a larger percentage of correct
responses than do those without calls. Of a total of 103
tests with colored cloths, which Mr. von Osten performed
for us, only 37% brought forth successful responses on
the part of the horse when visual signs were the only
directives and when there were no directions by means
of calls, whereas the total percentage of successful re-
sponses was 54%, if we add to the above those in which
the vocal exclamations helped to bring about success.
The corresponding percentages for the total of 78 tests
with the placards were 23% and 50%. Ina total of 110
color tests I myself obtained 31% correct responses under
the first head, and 56% under the second head. In a

EXPERIMENTS AND OBSERVATIONS 85

total of 59 tests with placards I succeeded in getting 31%
correct responses under the first head and 46% under the
second head. We must note that without verbal admoni-
tion only one-third of the tests brought forth correct
responses, whereas one-half succeeded when those in
which calls were used, are added. Still, this is a relatively
poor showing. In the most favorable series that Mr. von
Osten ever obtained in our presence—and there was only
one such—50% of the responses ‘ without admonition ’
were correct, and 90% when all the correct reactions, both
with and without admonition, were taken into account.

Not all the places in the row required the same amount
of assistance by means of calls. Those positions which
needed the most help, were those which it was most
difficult to indicate to the horse by the visual sign, i. e.,
the attitude of the questioner’s body. We noted above
(page 81) that the cloths at either end of the row were
less difficult to point out than those nearer the middle.
If our hypothesis holds true, we would expect that the
end cloths would involve fewer auditory signals in the
process of pointing out, and those within the row a
greater number of such signs. By way of illustration, I
will cite one series of tests in which Mr. von Osten was
questioner, chosen not because it is most conformable to '
my hypothesis but because it is the longest (48 consecutive
tests with five cloths) which I have. In the upper row I
am placing the successful responses without auditory
signs, in the lower those involving both auditory and
visual signs.

Place of the cloth I II Ill IV Vv
No. of sucessful } visual signs only e522 2 4
responses. visual and auditory signs 5 5 8 5 3g

86 THE HORSE OF MR. VON OSTEN

We see that without verbal admonition the first and last
places are most favorable for success, the second and
fourth far less, and the middle least favorable. These
differences disappear when admonitions are introduced,
for all of the places then have the same number of correct
- responses with the exception of the middle, which now has
even more than the others.

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, succes-
sively, each one of the six cloths in the row, and without
a single error,—and all this in the presence of Mr. Schil-
lings 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 achieve-
ments. None of them stood the critical test. It would
have been gratifying to have repeated some of the experi-

EXPERIMENTS AND OBSERVATIONS 87

ments 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 thor-
ough test, therefore, would have been doubly desirable.

CHAPTER III
THE AUTHOR’S INTROSPECTIONS

In the preceding chapter we asked: What is it that
determines the horse’s movements? Independent think-
ing, or external signs?—We found that it was solely ex-
ternal signs, which we described as certain postures and
movements of the questioner. Beyond a doubt these nec-
essary signs were given involuntarily by all the persons
involved and without any knowledge on their part that
they were giving any such signs. This is to be seen
from their statements, which cannot be cavilled at, as
well as from the fact that several of them even to-day
still doubt the correctness of the explanation which we are
here offering. I myself for some time made these invol-
untary movements quite unwittingly and even after I had
discovered the nature of these movements and had thus
become enabled to call forth at will all the various re-
sponses on the part of the horse, I still succeeded in
giving the signs in the earlier naive involuntary manner.
It is not easy, to be sure, to eliminate at once the influ-
ence of knowledge and to focus attention with the great-
est amount of concentration on the number desired,
rather than upon the movement which leads to a success-
ful reaction on the part of the horse. To some this may
appear impossible, but those who are accustomed to do
work in psychological experimentation, will not deny
the possibility of such exclusive concentration upon cer-
tain ideas.

88

THE AUTHOR’S INTROSPECTIONS 89

If we now ask: “ What occurred in the mind of the
questioners, while they were giving the signs? ”, the an-
swer can be found only by way of the process which in
psychology is technically called “introspection”, i. e.
observation of self. In the following we will give the
most important results of this process of self-observation,
which took place in the same period in which the observa-
tions recorded in the preceding chapter were made.

My first experiments were made while the horse was
counting or solving arithmetical problems and were as
follows: Mr. Schillings, who was alone with me in the
horse’s barn, asked me to think of several numbers, main-
taining that the horse would be able to indicate them cor-
rectly upon being asked. He stood to the right of the
horse, I stood erect and at the side of Mr. Schillings.
There was no one else present. Somewhat skeptical in
attitude, I concentrated my mind consecutively on five
small numbers. Hans tapped one of them incorrectly,
one correctly and three by one unit too many. At the
time I considered these attempts as unsuccessful and cred-

ited some curious chance with the answers which were
correct, or nearly so. This was a mistake, for often
during the following days, and in the absence of Mr. von
Osten, the horse would give correct answers. Others, of
course, would be incorrect, and usually the mistakes
would be by one unit,—so that I soon saw that even in
the horse’s errors there lay some system. It will be seen
that Hans responded to me from the very beginning, un-
doubtedly because I had had the opportunity of watching
Mr von Osten and Mr. Schillings and had thus patterned
my behavior after theirs. I was not at first successful in
gétting the horse to respond correctly in the case of large
numbers. For in order to get complete control over the

90 THE HORSE OF MR. VON OSTEN

horse, and, what was, as I later discovered, more to the
point, control of myself, some practice was needed. But
I was able to work with the horse quite successfully,
while I was still in the dark as to my own behavior.

From the very beginning Hans responded as promptly
to those questions which I articulated merely inwardly,
as to those which were spoken aloud. That all formula-
tion of the question was unnecessary, however, was shown
by the following experiments. If, for example, I did not
think of any particular number until after the horse had
begun to tap, and then fixed upon 5, he would tap 5. If,
however, I told him to count to 6, but gave no further
thought to the command after he had begun tapping, I
would get an entirely wrong response. It was easy to
obtain any answer one wished to a question, simply by
focussing consciousness, with a great degree of intensity,
upon the answer desired. Thus Hans answered my ques-
tion: “How many angles has a hexagon?”’, first by 6,
then 2, then 27, in accordance with the numbers that came
into my mind. The animal always followed the ideas
which were in the questioner’s mind, and never his words,
for it was with the former that the movements upon which
the horse depended were bound up.

It was not enough, however, simply to imagine the
number desired. It was furthermore necessary that the
questioner be conscious of the moment when the horse
reached that number. Larger numbers (above 6) were
therefore, successful only when every single tap was in-
wardly counted to the end. The manner of counting was
indifferent. Thus I counted 6 as follows: 1, 2, 3, 4, 5,6,
and later: 6, 5, 4, 3, 2, I, and then again: 6, 6, 6, 6, 6, 6.
Finally I used the Greek letters and also nonsense syl-
lables. And in all cases I obtained six taps, the correct

THE AUTHOR’S INTROSPECTIONS gI

response. If, however, I simply counted the taps without
knowing when the desired number was reached, the re-
sponses were always incorrect, e. g., I counted

For No, 10: 10, 10, 10 —s continuously, Hans tapped 13,

“ © FO: yy 8 310 16 «“ “ 10,
“ “ Jy2: 12, 12, 12 continuously “ re CH
oS Te: a, 2, 3 to 12 “ “ 1

In the case of smaller numbers, on the other hand, one
often obtained correct results without counting. In this
I am borne out by Mr. Schillings. It was merely neces-
sary to image vividly the number 3, or 4, or even the
name of a week-day or of a month without the number
which would indicate it. In the last of these cases the
number corresponding to the day or the month (e. g. 3 for
Tuesday, 5 for May, etc.), though not consciously pre-
sented, still evidently lay at hand in the subconscious.
To use a popular expression, I usually had a “ feeling ”
when Hans had arrived at the right number.

It was furthermore found that it was not only neces-
sary to count to, or to think of, the number desired, but
that this must take place with a high degree of tension of
expectancy—that: is, a strong affective element must
enter in. The state required for a successful response
was not the mere passive expectation that the horse would
tap the number demanded of him nor the wish that he
might tap it, but rather the determination that he should
do it. An inward “ Thou shalt”, as it were, was spoken
to the horse. This affective state was registered in con-
sciousness in terms of sensation of tension in the muscu-
lature of the head and neck, by intraorganic sensations,
and finally by a steadily rising feeling of unpleasantness.
When the final number was reached, the tension would

92 THE HORSE OF MR. VON OSTEN

suddenly be released, and a curious feeling of relaxation
would ensue. I have made a series of tests to determine
the most favorable degree of tension in expectation. It
was possible to distinguish with certainty, three degrees
of tension besides the state of utter relaxation,—all of
which I measured by means of the differences in the sen-
sations of tension. In cases of tension of the first degree
(greatest concentration) the responses were usually cor-
rect, a few, however, were lacking by one unit. There
was therefore in the latter instance a premature release
of inner tension. In cases of tension of the second de-
gree all answers were correct except a very few which
were too great by one unit. In cases of tension of the
third degree, many answers were wrong, and usually by
several units too many. I wished to have the horse tap
10, with the lowest degree of concentration. He tapped
13, then in a repetition of the test, 12. I thereupon in-
creased the tension, Hans then tapped 8. I decreased the
tension once more, but so that it was somewhat greater
than at first. Hans tapped 10 correctly. At another time
I tried to have him tap the number 5, with a low degree
of tension. He tapped 6. I intensified expectation and
Hans tapped 4. I again decreased it, and he tapped 5,
comme il faut. Apparently, therefore, the most favorable
degree of tension was one between the first and second,
—the latter being the least favorable. After some prac-
tice a lesser degree than was used in the beginning suf-
ficed to evoke adequate reactions. The flow of nervous
energy to the motor centers of the brain evidently became
facilitated through practice. It will be easy to understand
why the first days of experimentation caused intense
headaches, which later never occurred.

Whenever, in the foregoing, we spoke of a certain de-

THE AUTHOR’S INTROSPECTIONS 93

gree of concentration which had to be attained, it is not
to be understood that the same tension had to be main-
tained throughout the test, from the horse’s first tap to
his last. But rather, that it began with a low degree, and
gradually increased as the final unit of the count was being
approached. It may best be represented by a curve whose
maximum represents that degree of tension which we
have been discussing. The rise to this maximum which,
when attained, was followed: by a sudden fall, did not
always occur in the same manner. Three types of curve
may be distinguished, which were first discovered in
purely empirical fashion, and later reproduced volun-
tarily for purposes of experimentation by diagramming
before each test the intricate curve of the varying degrees
which the intensity of concentration was to assume. The
types may be described as follows:

I. Here the tension curve rises steadily from begin-
ning toend. This type preponderates in the case of small
numbers. Thus, when I asked the horse: “ How much is
2 plus 4?”, the tension increased slowly with every tap
from the moment I began counting, until the final tap
was reached, when it was again relaxed. Externally this
relaxation is noticeable as a slight jerk.

II. In this case the curve does not rise at an equal rate,
but rather more slowly at the beginning and later under-
goes a sudden increase, or the tension increases immedi-
ately at the beginning, remains constant for some time
and then ascends to the maximum. This curve is the
rule in the case of large numbers and evidently means
economy of physical energy, for experience soon taught
that a steady increase in tension from the very beginning
soon brought it to a level which cannot be long main-
tained and usually leads to a premature relaxation. In

04 THE HORSE OF MR. VON OSTEN

the case of very large numbers the alternation of the slight
and the sudden increase may be repeated several times,
and at times it may even sink below a level which has al-
ready been attained, thus making a wave-like curve.
III. The third type of curve shows a sudden jump be-
tween two units at a certain point in its course. This
may occur in the cdse of both small and large numbers
but only when the highest or first degree of concentration
is employed (see page 91). Such a jump frequently
occurs in the transition from the tap preceding the last to
the last one which is being eagerly expected. Relax-
ation—with the upward jerk and raising of the head—
here occurs at the normal time; Hans taps to the end with
his right foot. Oftener still the “jump” described oc-
curs while passing over to the number just before the
last. The goal seems within reach and the mental tension
relaxes, and with it the physical tension,—the head gives
a slight jerk and Hans makes the back-step. Since, how-
ever, another tap is still awaited with some degree of
tenseness and, since complete erection of the head does
not follow immediately upon the jerk of the head, the
horse gives another tap with the left foot. Thereupon
occurs the complete relaxation of attention, and the as-
sumption of the erect posture on the part of the ques-
tioner. That this is psychologically the clue which leads
to the final tap, will readily appear from the following
remarkable fact: I was able to bring about at will either
the back-step with the right foot, or the additional extra
tap with the left foot by concentrating the mind either
upon the last unit or upon the one just preceding it. In
either case the movement which served as stimulus to the
horse followed naturally upon concentration on the num-
ber. I could of course also control the response by direct

THE AUTHOR’S INTROSPECTIONS 95

voluntary control of the movements involved. Hans
thus solved for me the same ten problems first with the
back-step, then with the extra final tap.

Finally we will indicate the one true inner cause of the
difficulty in getting the number 1 as a response. It is not
easy to relax attention immediately after having just
begun to concentrate. Relaxation, therefore, often oc-
curs with a certain retardation, and the result is a belated
jerk of the head.

Briefly, I would also mention a few of the more inter-
esting introspective observations which were made in
situations in which the horse responded with movements
of the head for answers such as “ yes” and “no”, “up”
and “down”, etc. From the very beginning I put ques-
tions to Hans which would have to be answered by a
shake of the head. It often happened that instead of indi-
cating “o”, Hans would begin tapping some number.
But the wonder of it was that, in many cases, he re-
sponded properly. I knew only that I inwardly pro-
nounced the word “null” (zero), and that I looked ex-
pectantly at the horse’s head. In the case of questions to
which I expected the answer “ yes” or “no”, I imagined
myself enunciating the answer, i. e., I used motor im-
agery. The tests failed, the moment I employed only
visual or auditory imagery, whereas, motor imagery was
always effective in calling forth correct reactions.* When

* Thus it is possible to think of the word “no” in three differ-
ent ways. I may get a visual image of the written or printed word,
or the auditory image of the word as spoken by another person, or
finally I might think of it in terms of images of the sensations of move-
ment which would arise if I myself were to enunciate or write the word.
And so, in like manner, I could think of any other word in terms of
either visual or auditory or motor imagery. In all probability the

96 THE HORSE OF MR. VON OSTEN

the proper response was “up” and “down ” I would
think of those directions in space, and likewise with
“eft” and “right” in which case also I would put my-
self in the horse’s place.

While I was still ignorant of the nature of the neces-
sary movements, the tests were successful only when I
had put the question aloud or in a whisper, but never
when I failed to enunciate, i. e., when I merely had the
question in mind (“in idea”). But this also became
possible after a little practice, although I could not then
give an explanation for my success. Except in one in-
stance, we could discern no difference between problems
spoken and those merely conceived by Mr. von Osten
who had had the advantage of long practice. But the one
exception deserves mention. The old gentleman com-
missioned Hans, presumably without uttering a word, to
step backward to the left. Hans thereupon responded by
giving his entire repertoire, as follows: He moved his
head to the right, then to the left. Then he leaped for-
ward and repeated the same movement of the head. Here-
upon he stepped backward and signified a “ yes” by a
movement of the head. He then lowered his head and
made two leaps forward. After this performance Mr.
von Osten repeated the same command aloud, and in every
case Hans responded properly. Again the silent com-
mand was given and again the horse responded with the
series of reactions described above, lowering his head

auditory and motor always occur together,® but still it is possible to make
the one or the other predominate.

It appears that the imagery of most persons is a mixture of auditory-
motor and visual elements, with a predominance of one or the other
kind. Individuals who utilize almost exclusively the visual (as does the
author, as a rule), are rare, But rarer still is the pronounced motor type.

THE AUTHOR’S INTROSPECTIONS 97

leaping forward, etc. In this experiment, without excep-
tion, the spoken command evoked adequate reactions,—
the silent command, an incorrect response. Evidently.
the impulse to movement was not so great with the mere
conceiving of “right”, “left”, etc., as when the words
were enunciated. It, therefore, required some practice
on my part before a sufficiently strong movement-impulse
became associated with the idea. All this is in no wise
at variance with the fact that tests involving counting and
computation were as successful when the problem was
given in silence, as when it was spoken. The signs for
tapping, viz.: inclination and erection of the head and
body, followed the question. The question therefore be-
came superfluous. On the other hand the signs for head-
movements on the part of the horse, were given while the
question was being put. I ask, which way is “ upward”,
and at the same time I look upward. In this case there-
fore the question itself is not entirely insignificant.—I ex-
perienced greater difficulty in getting Hans to respond
with the head-movement to the left. After much prac-
tice I was able to evoke this movement by means of
giving the command aloud, but never by means of the
“silent”? command. Accidentally I hit upon a device by
means of which I attained this end also. Iasked the horse
aloud “ Which direction is left? ”,—whereupon he re-
acted properly; then I immediately repeated the question
silently, and was successful every time. My mental atti-
tude here was still the same as when I put the question
aloud. What sort of an attitude this was, I could not, of
course, have stated explicitly at the time. I could not,
therefore, awaken it at will—and if I allowed but a
minute to elapse between the spoken and the silent ques-
tion, the vivid after-effect (the so-called “ primary mem-

98 THE HORSE OF MR. VON OSTEN

ory image”) soon disappeared and the test was wholly
unsuccessful. Practice, however, soon helped me to over-
come this last difficulty also. I believe that my inability
to evoke this specific reaction on the part of the horse,
lay in the unfavorable position which I assumed, for it
did not allow the horse to preceive my movements easily,
For the same reason, Hans would at first indicate “no”
and “zero” by turning to the right, seldom to the left.

As in the case of counting, a high degree of concentra-
tion was also necessary here, but with this difference,
that here attention was directed to ideas present to the
mind, (“yes”, “no”, etc.), whereas in the counting
process attention was directed toward expected sensory
impressions (i. e., the taps of the horse).

All that has been said thus far is readily understood
psychologically. The following curious fact, however, is
noteworthy. Hans used the head-movement to indicate
two such different concepts as “ zero” and “no”’; it ap-
peared therefore that in both cases he was receiving the
same kind of directive. Observation proved that such
was the case and the directive in question was none other
than an imitation in miniature, or rather a movement
anticipatory of the expected head-movement of the horse.
Now, whereas the signs for “up”, “down”, “ right”,
and “left” were natural expressive movements which are
normally associated with the corresponding concepts, this
cannot be said to be true of “no* and “zero”. My
laboratory observations (see page 107) lead me to con-
clude that the movements, by means of which the concepts
“no” and “zero” are naturally expressed, are quite dif-
ferent; and neither of these corresponds to the signs for
“zero” and “no” which the questioner involuntarily
gave to Hans. What was the genesis of these unnatural

THE AUTHOR’S INTROSPECTIONS 99

forms of expression? If we might assume that the ques-
tioner always had in mind the movement he awaited on
the part of the horse, and never thought of “zero” or
“no”, then the contradiction would solve itself. But I
must deny decidedly that I ever thought of the movements
of the horse’s head, and Mr. Schillings, whom I ques-
tioned on this point, agreed with me in this, in so far as his
own mental processes were concerned. I can see nothing
for it but that in this instance the expressive movements
normally connected with the concepts “zero” and “no”
have been replaced by other forms, without the questioner
becoming aware of it. That such displacements may
occur, has been shown by the tests described on pages 107
to 112. That they did occur in this instance may be
concluded from the following observation. In respond-
ing to me, as well as to Mr. Schillings, Hans always
moved his head first to the left, then to the right, never
in the opposite order. That this was not a peculiarity of
the horse, but must be ascribed to the signs which were
given him, is shown by the possibility of inverting the
order under experimental control (page 77). Frequently
Mr. Schillings and I had seen the horse respond to his
master by means of such head-movements, and the order
was always, without exception, the one mentioned. It
must be assumed therefore that the horse’s movement,
which we so often noticed, made such an impression upon
us, that afterwards it was regularly reproduced on our
part quite unconsciously, so that Mr. Schillings never, and
I only after a long time, became aware of the whole
process.

In closing, just a word as to the discovery of our own
movements. I soon noticed that every pronounced rais-
ing of the head or trunk brought about an interruption

10o0o THE HORSE OF MR. VON OSTEN

in the horse’s response. But only by observing the final
movement in the case of Mr. von Osten did I discover
that I, too, performed a slight erection of the head. Ob-
servation of others was less difficult than the observation
of one’s own movements. As in the case of all other signs
given to the horse, these movements were so slight that
they were prone to escape notice even though one’s whole
attention were concentrated upon their detection. I also
questioned whether in my attempts to disturb the horse by
means of loud calls, it were really the call or some simul-
taneous involuntary movement which was the true cause
of the interruption. The doubt was justified, for when
I finally learned to cry out vehemently without making
the slightest move, all my crying was in vain. Also it
had seemed to me at first as if I were able to induce the
horse to rear, not only by means of the proper sign or
movement, but also by a mere command, but I found
later that in every case there was always some movement,
were it ever so slight. Finally I tried to simulate volun-
tarily the oft-mentioned involuntary jerks of the head.
Although it is not very difficult to execute them at will
with almost the same minuteness as when they were per-
formed involuntarily, I still did not succeed in getting a
series of such jerks of equal fineness throughout. In
spite of (and partly on account of) the most concentrated
attention, there would be from time to time a jerk of
somewhat greater extent and energy. As soon as the
movement had been executed, I was able to form a good
judgment as to its relative extent, but I was unable to
regulate the impulse beforehand.

With the following comment the chapter will be con-
cluded. Introspections are necessarily subjective in char-
acter. If they are to possess general validity, they must

THE AUTHOR’S INTROSPECTIONS - 101

be borne out by evidence furnished by others—and this
to a greater extent than is necessary for other forms of
observation. It was hardly possible to get corroboration
from the other persons who had worked. with Hans, for,
although some of them were excellent observers of ex-
ternal natural phenomena, few of them had had the nec-
essary amount of practice in introspection. The neces-
sary confirmation, however, was had in laboratory tests,
which we shall presently describe.

CHAPTER IV
LABORATORY TESTS

Tue tests which are to be briefly reported here, were
begun in November, 1904, and were carried out at the
Psychological Institute of the University of Berlin.
The purpose was twofold: first, to discover whether the
expressive movements noted in Mr. von Osten, Mr. Schil-
lings, and others, were to be regarded as typical and to
be found in the majority of individuals,—and secondly,
to ascertain in how far the psychical processes which I
had noted in my own case and which I believed to lie at
bottom of these movements, were paralleled in, and con-
firmed by, the introspections of others. The effort was
made to make the experimental conditions as nearly as
possible like those under which the horse had worked.
The affective atmosphere which colored the situations in
which the horse took part, could not, of course, be trans-
ferred, but this was in some respects an advantage. One
person undertook the rdle of questioner, another—myself
—that of the horse. The experiments fall into three
groups, corresponding to the types of the horse’s reac-
tions: I, tests in counting and computation; 2, tests in
space reactions; 3, tests in fetching or designating ob-
jects.

In the experiments in counting and computation, the
questioner, standing at my right, thought with a high
degree of concentration of some number (usually be-
tween I and Io, but sometimes also as high as 100), or

102

LABORATORY TESTS 103

of some simple problem in addition. Then I would
begin to tap,—but in human fashion with my right hand,
rather than with my foot—and continued until I be-
lieved that I had perceived a final signal. I thus tested,
all in all, twenty-five persons, of every age and sex (in-
cluding children of five and six years), differing also in
nationality and occupation. None of them was aware
of the purpose of the experiments. It could not escape
them, to be sure, that they were being watched. It was
also evident to them that the things noted were certain
tensions and movements; but none of my subjects dis-
covered what the particular phenomena were that I was
looking for. Only in a few isolated instances did they
report that they were conscious of any movements on
their part. With the exception of two persons, they all
made the same involuntary movements which were de-
scribed in chapter II, the most important of which was
the sudden slight upward jerk of the head when the final
number was reached. It was at once evident that the di-
rection of this jerk depended upon the position which one
had asked the subject to assume at the beginning of the
test, the direction changing whenever the position was
changed. Thus, if the subject stood with head bowed—
the body either being held erect or likewise bowed,—then
release of tension would be expressed physically by an
upward jerk. (Occasionally the entire trunk is slightly
raised, so that it was possible to observe this physical
reaction when standing behind the subject). If the sub-
ject had bent his head backward, the “ psychological mo-
ment” was marked by a forward movement, (although
under certain conditions the head was, in such a case,
observed to bend still farther backward). If during the
tests the head was bent slightly to the right, then the re-

104 THE HORSE OF MR. VON OSTEN

action was expressed in a movement toward the left, and
vice versa, if it had been on the left, it was bent to the
right. If the subject had been bending his head forward
and to the right, he then raised it upward and to the left,
etc. In all of these changes of position I noticed an in-
termediate posture which, to be sure, it was not always an
easy matter to discover,—viz.: an upright position in
which there was discernible no manner of head-movement
or only a slight tremor. If the subject was lying on his
back with his head supported, then there was noticeable a
very slight movement to one side. In this same way a
number of other positions were tested in order to dis-
cover for each the characteristic movement expressive of
release of tension. It would therefore appear that the
raising of the questioner’s head, which served as the
signal for stopping for Mr. von Osten’s horse, was but
one instance of a general law which may perhaps be stated
thus: The release of muscular tension which occurs with
the cessation of psychic tension, tends to bring about that
position of the head (and body) which, at the time, repre-
sents the slightest amount of muscular strain —These
movements seldom were pronounced enough to be com-
pared to motion through a distance of one millimeter, in
a very few cases only did they attain to the magnitude of
one or two millimeters. I failed to note them entirely,
however, in only two individuals, two scientific men whose
mode of thought was always the most abstract, and one
of these was, in spite of repeated attempts, unable to elicit
any response whatever on the part of the horse.

In the cases of the more suitable subjects I was able
to indicate not only the number they had in mind, but
also the divisions in which the number was thought, thus
12 as 5 and 5 and 2, or the same number as 2 and 5 and 5,

LABORATORY TESTS 105

and I was also able to determine the addends in the
addition—i. e., whether the problem had been conceived
as 3+2=5 or as 2+3=s. It frequently happened that
in the beginning I would sometimes mistake these subdi-
visions, which were recognizable by the less pronounced
jerks, for the final number. Thus I would often respond
with 4 instead of 8, or 3 instead of 9, or with 3 when the
problem was 3+-2, just as Hans had so often done. In
these tests, too, the difficulty of getting the number 1, as
well as the larger numbers, came to light. Thus three
times in succession 17 was indicated as 4, as 9, and as 17.
But after some practice I was able to give numbers as
high as 58 and 96. The frequency of the errors of one
unit too many and of one unit too few is also noticeable
in these tests.

We also found desirable corroboration, by trustworthy
subjects, of the introspective observations of the author,
which were reported in Chapter III, with regard to the
significance of concentration and the curve of attention.
It is hardly necessary to mention that no attempts were
made to influence the subjects in their accounts by asking
suggestive questions. The most valuable feature about
these tests was that the mute horse had now been re-
placed, as it were, by an animal capable of speech, and
that it was now possible to follow the same process both
from within and from without. Two illustrations may be
welcome. The one who took the part of the horse gave
three taps and made the following entry: “ At 3 I saw a
slight upward jerk of the head on the part of the ques-
tioner”. The questioner however had thought of 4, and
made the following note, without knowledge of the other’s
entry: “I was aware of extreme tension, so that it
was impossible for me to get beyond 3”. Or again, the

1066 THE HORSE OF MR. VON OSTEN

‘horse’, reacting to a movement on the part of the ques-
tioner, stopped at 3, but the latter, having intended to ob-
tain 2, made the following entry: “I noted clearly that I
ceased thinking of the number too late, and did not put
on the brakes, as it were, until I had arrived at 3”. We
see that errors here were entirely the fault of the ques-
tioner, just as had been the case in the tests with Hans,
(See page 15rf.).

In a second group of experiments I asked a subject to
fix his mind upon certain concepts, such as “up”, or
“down”, “right” or “left”, “yes” or “no”, and
others, in any order he pleased, but with the greatest
possible degree of concentration. The subject each time
had the choice of four or six concepts, and he was told
to think of one of them at the signal “ Now!”. How he
was to ‘think’ the concept was left entirely to him.
He was also told to interpolate the series with a ‘blank’,
that is, to think of nothing at all. Standing opposite the
subject, I tried to guess at the mental content of the per-
son’s mind, on the basis of expressive movements. Some-
times I reacted by shaking or nodding the head, etc., just
as Hans had done, but as a rule I was content to say
the word which I thought the subject had in mind. With
twelve subjects (a total of 350 tests) I made an average
of 73% correct responses, and in the more favorable cases
I attained even 90 to 100% correct responses. Very
slight involuntary movements of the head and eyes,
which showed but little individual variation, and always
occurred when the subject began to fix upon the concept,
were the signs which I used as cues. As in the case of
the movements expressive of the release of tension, which
I discussed above, these movements, too, occurred with-
out the subject being aware of them, (except in those

LABORATORY TESTS 107

rare cases in which they had once or twice been especially
pronounced). Indeed, it was very difficult and in some
cases almost impossible for those persons whom I had
initiated into the secret, to inhibit them voluntarily.
“Up” and “down”, “right” and “left”, were ex-
pressed by movements of head or eye in those directions,
“forward” by a forward movement of the head, “ back’”
by a corresponding movement. “ Yes” was accompanied
by a slight nod of the head; “no” by two to four rapid
turnings of the head to either side.* “Zero” was ex-
pressed by a movement of the head describing an oval in
the air. Indeed, it was even possible to discover whether
the subject had conceived of a printed or a written
zero, for the characteristics of both were revealed in
the head-movements. I was able later to verify this
graphically. With Ch. as subject, I made 70% correct

* It was Charles Darwin 7 who first pointed out that the expressive
movements (of the coarser sort) to be noted in nearly every race and
people show a great, though by no means complete, similarity. The
similarity is most pronounced in the shaking of the head to signify ne-
gation and nodding to denote affirmation. It will be noted that the
former is essentially of the nature of a turning toward, and the latter
atuming away. These same movements have been reported in the
case of the blind and deaf Laura Bridgman,® and we have been ex-
plicitly assured that they were a spontaneous development, and not
acquired by imitation. For it is by imitation and never before the
completion of the first year, that our children acquire these move-
ments. On account of his unreliability, we can put but little stock in
the statement of Garner,!° a writer on the speech of monkeys, that
these same gestures have been observed in the case of those animals.
My experiments show that the same movements, greatly diminished in
scope, as a rule accompany the mere thought of “yes,” “no,” etc. I
cannot, however, regard the assertion as an established fact that every
thought process whatsoever is connected with some form of muscular
movement, as has been generalized by the French physiologist Féré,™
and the American psychologist Wm. James.

ly
108 THE HORSE OF MR. VON OSTEN

interpretations in a total of Zo tests; with von A. as sub-
ject, 72% in a total of 25 tests. And finally I was able
to interpret the signs without any errors at all. It was
not absolutely necessary to look directly at the subject’s
face. Even though I focussed a point quite to one side,
so that the image of the subject’s face would fall upon a
peripheral portion of my retina, I still was able to make
89% correct interpretations in a total of 20 tests—This is
not astonishing after all, when we recall that the periphery
of the retina possesses a relatively high sensitivity for
movement impressions, although its chromatic sensi-
tivity is very low.*

It was assumed, as indicated on page 99, that in the
case of Mr. Schillings and myself the movements natur-
ally expressive of “zero” and “no” had been displaced

* The productions of mind-readers, so-called, also, are based upon the
perception of involuntary movements, insofar as they are not based
upon pre-arranged schemes and trickery. But there we have to do
principally with tactual perception, since the reader touches the hand of
the subject and is guided by its tremor. Some of the expert mind-
readers, however, conduct tests without touching the subject. They
depend chiefly upon auditory impressions: the sound of footsteps,!?
involuntary whisperings }4 and the changes in the subject’s respiration 5
and the murmuring of the spectators. To a less degree visual signs also
are involved : posture and facial expression of the subject, and move-
ments of eyes and lips.6 Even the heat radiating from the person's
body is supposed to have some influence? And my own experience
has taught me that surprising results may be obtained by the utilization
of the movements described in the preceding chapter.

It may be that these truly microscopic movements also play some
part in bringing about the success of some of the experiments in telep-
athy, 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.

#
LABORATORY TESTS 109

—without our being aware of the fact—by others, viz.:
those which the horse required as directives for his reac-
tions. Since this was the case, we tried to discover if a
similar displacement could be brought about experimen-
tally. 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.

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 sub-
ject 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, how-
ever, 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.

110 THE HORSE OF MR. VON OSTEN

In the case of another subject (B.) in whom normally
the thought of “ up” was accompanied by a slight rais-
ing of the head, and “ down” by a downward movement,
these natural forms of expression disappeared entirely as
a result of my arm movements to the right to indicate
that I inferred his having in mind the thought of “up”,
and to the left when I inferred that he was thinking of
“down”. Instead, there appeared not merely the de-
sired movements to the right and left, but rather move-
ments upward to the right and downward to the leit.
That is, instead of a complete displacement of the old by
the new, there occurred a combination of the two.

A third type of result appeared in still another sub-
ject (Ch.), who normally expressed the concepts “ right ”
and “ left” by eye or head movements (never both kinds
at the same time) to the right and left. Here my arm
movements up and down caused the eye and head move-
ments to be made simultaneously, so that the thought of
“right” found expression in an upward movement of
the head and an eye movement to the right, and the idea
of “left” in a downward head movement and a move-
ment of the eye to the left. The subject had no knowl-
edge of this process, and it took six tests to bring about
the new reaction. From that point onward the new move-
ments were so well established that, depending upon
them for my cue, I was able to make 32 correct infer-
ences in a total of 40 tests. During the latter part of this
series I blindfolded the subject, so that I could not see
the movements of his eyes, and therefore had to base my
inference entirely upon his head movements.—After re-
moving the bandage, at the end of the series, I told the
subject that I would go through another series, in which
I intended to indicate his thought of “ right ” by an arm

LABORATORY TESTS III

movement downward (instead of upward as heretofore),
and his thought of “left” by a movement upward.
(This he regarded as an idle whim of mine). It was
only after the twelfth test that the former “ association ”
which I myself had caused to be established, was com-
pletely displaced by the new. The thought of “right ”
was now accompanied by an eye movement to the right
and instead of a raising there was a lowering of the head.
A corresponding change occurred in the head movement
expressive of the thought of “left”. These responses
were occasionally varied by some in which only the head
movement or only the eye movement occurred. But
these movements were always to the right, or downward
and to the right, at the thought of “ right ’,—and to the
left, or upward and to the left, at the thought of “left”.
In ten tests I made ten correct inferences. After the new
association appeared firmly established, I ceased respond-
ing by means of arm movements, and indicated my
‘guesses’ by word of mouth. At first the newly acquired
movements continued to appear promptly in the subjects.
But gradually they tended to become more uncertain and
finally disappeared, as readily as they had appeared, and
the normal conditions were once more established. Nor
was there any tendency to reappear on the following day
in another series of tests. (Those just described had
been made on one day in the course of an hour or two).
But as soon as I again used the earlier method of arm
movement to indicate my inferences (raising the arm for
“right”, lowering it for “left”), the former artificial.
association was again established, although not until
some 14 tests had been made,—during which the normal
movements to the right and left were often inhibited and
during which the conditions were, on the whole, chaotic.

112 THE HORSE OF MR. VON OSTEN

The new association, thus re-established, remained con-
stant during the ten tests of the remainder of the series,
but has very probably again disappeared long ere this.
In the case of this subject it appears therefore that the
new associations were superimposed upon, but in no
sense displaced, the normal expressive movements. Nor
did the two coalesce (except in a few exceptional cases),
but tended as a rule to occur independently of one an-
other.

I would emphasize once more that none of the subjects
had any knowledge of the purpose or meaning of the ex-
periments. Also, I was convinced by questioning the
subjects afterwards that none of them—and this is the es-
sential point—had merely conceived of the arm movement
which they were expecting me to make, instead of con-
centrating thought upon the idea of “right” or “left”.
On the contrary, all of them considered my particular
movements mere vagaries and without purpose, and they
felt perfectly certain that they were in no wise influenced
by these movements. Also, none of the subjects was con-
scious of any movements on their part, except one, who
was at times aware of her eye movements to the right,
but never of those to the left, (see page 111), nor of the
head movements which for us constituted the phenomena
of prime interest. When I asked my subjects what they
believed to be the cue upon which I based my inferences,
they invariably responded with probable explanations
which were always wide of the mark, and those to whom
I disclosed the cue—(after the experiments were com-
pleted), were thoroughly astonished.

In the tests just described we had to do only with such
ideas or concepts as normally were associated with some
stereotyped form of expressive movement (see page 106).

LABORATORY TESTS 113

I now chose a group of ideas which are not normally asso-
ciated with a particular form of motor expression peculi-
arly characteristic of them, and sought to establish arti-
ficially such a connection with some arbitrary movement,
without consciousness of the process on the part of the
subject. Thus I asked one subject (Miss St.), who had
no intimation of the aim of the tests, to think of the fol-
lowing words in any order she might choose: “ Ibis”
(ibis), “Irbis” (panther), “ Kiebitz” (plover) and
“ Kurbis ” (pumpkin). I said that I would react to her
thoughts by means of arm movements forward and back-
ward to the right and to the left, respectively. 15 out of
20 tests were successful, without the slightest suspicion
on the part of the subject (whose whole attention was
concentrated on the word-content), that she was giving
me the necessary directives in the form of very minute
movements of the head and eyes to the right and left, etc.
She was greatly astonished that I should be able to guess
words so much alike,—(she did not know that the ele-
ment of likeness was productive of no difficulty). When,
during one of the tests, the subject happened to think
spontaneously of the movement she was expecting me to
make, she became confused, and as a result the number
of my sucessful reactions suddenly fell. I never would
have discovered the cause, had not the subject enlightened
me without my asking.

I repeated this series with three other persons, who
had had some psychological training. I did not use the
same movement for each word in all three cases, but in-
dicated the word “ Kiebitz ”, for instance, by means of an
upward movement in one case, by turning the head to the
right in another, etc. In one of the three cases the tests
were almost wholly unsuccessful. The cause for this

114. THE HORSE OF MR. VON OSTEN

came to light later, but it would involve too much ex-
position to discuss it at this point. In the case. of the
other two persons, the tests were successful beyond ex-
pectation. I had made my various arm movements only
a few times when they presently began to raise their
heads slightly when thinking of “ Irbis”, and to move it
to the right at the thought of “ Kirbis”, etc. In the two
series of 35 tests I did not have a single error. In a num-
ber of instances I succeeded in guessing the word upon
which the subject had decided, even before the test
proper was entered upon—i. e., before the signal for con-
centration had been given. Nothing surprised a subject
more than the remark: “ You are intending to think of
the word ‘ Kiirbis’”’, or “ You had thought of concentra-
ting your mind upon ‘Ibis’ but later decided in favor
of ‘ Kiebitz’”’, yet nothing could be more simple. Be-
fore every test the subject would consider what word he
would fix upon, and while he was saying to himself “I
will choose ‘Ibis’”’, the proper movement would accom-
pany his decision, although it was only very slight, be-
cause attention had not yet attained the degree of con-
centration which was employed in the test proper.

In these experiments also, the subjects, whom I know
to be absolutely trustworthy, declared that they never
thought of the arm movements which I was to make.
They regarded them as being quite irrelevant. Also—
with but one exception—they thought of the objects, in
so far as they imaged them visually, as being directly
before them, and not off in the direction indicated by my
arm movements. Thus they did not image the plover
(“ Kiebitz””) as being on the wing, when I raised my
arm, or as resting on the ground, when I pointed down-
ward, etc. One of the subjects had done this occa-

LABORATORY TESTS 115

sionally, but by no means regularly. He was therefore
asked to localize all objects in the same place, i. e., directly
in front of him at the level of the eye. He complied with
this request, but no change, whatever, was observed to
occur in his expressive movements.

In order to overcome the difficulty just mentioned, I
selected another subject (Miss von L.), whose power
of visualizing was very slight, and requested her to fix
her mind upon four words which I had selected because
they were not, necessarily, associated with a particular
image. The order in which the words were to be thought
of, was entirely optional on her part. The words were
“Form ”, Inhalt”, “ Mass”, and “Zahl”, (form, con-
tent, measure, and number), and each of them I ac-
companied, with a certain definite arm movement. The
subject always pronounced the word inwardly as em-
phatically as possible, but without ever imaging the cor-
responding arm movement. Often, it must be noted,
she did not know whether or not the movement which
I made was the proper one. And yet she, too, soon fell
into line in the matter of executing unconsciously the
characteristic head movements. In a total of 50 tests, I
was able to make Io correct guesses in the course of the
first 20 tests, 8 in the next Io tests, and 19 in the last 20
tests. Miss von L. noted only a few of her upward head-
movements, viz.: those that were especially pronounced
(movements through about 2 millimeters), but of the
others she knew nothing. The same experiment was re-
peated with a psychologist, well-trained in introspection,
as a subject. Success was even greater here. But no
matter how closely the subject observed himself, he was
unable to solve the puzzle.

Variations which were introduced in these tests, I

116 THE HORSE OF MR. VON OSTEN

will only mention in passing. Thus, instead of making
an arm movement, I, in some cases, would tap with my
foot, for “Ibis” once, for “ Kiebitz” twice. The sub-
ject could not see my feet. The involuntary movement-
expression which became associated with “ Ibis ”’ was one
nod of the head, with “ Kiebitz” two nods, etc. Here
our only concrn was to show that unconscious change
in natural expressive movements and the acquisition of
artificial ones are possible in the case of psychically
normal subjects trained in introspection.

I was not satisfied with convincing myself subjectively
of the facts indicated, but sought to fix them objectively,
by means of a graphic method. For this purpose I used
the device mentioned by Prof. R. Sommer for the analysis
of expressive movements.® The purpose for which
Prof. Sommer’s apparatus had been constructed, was to
record the involuntary tremor and movement of the
hand. These movements, of course, take place in the
three dimensions of space. By means of three levers it
is possible to record the movements upon the flat surface
of a smoked paper fastened to the revolving drum of the
kymograph, the movements in each direction being re-
corded by a separate lever, in such a way that the three
curves thus made represent the analysis of a single move-
ment into its three dimensional components. By making
slight changes, which tended to complicate the experi-
ment somewhat, I adapted the apparatus to the measure-
ment of movements of the head. The method of experi-
mentation was the following. The subject whose move-
ments were to be registered, was placed in the device
in such a way that his trunk and head were bent slightly
forward, the latter a little more than the former. This,
it will be remembered, was the usual position of the

LABORATORY TESTS 117

questioner when working with the horse. Three levers
were attached to his head in such a way that every move-
ment backwatd or forward would act upon the first
lever, every movement to the right or left would move
the second, and every movement of the head upward or
downward would be recorded by the third. With regard
to the sensitivity of the machine, micrometric determina-
tion showed that when the subject was properly installed,
movements through so small a distance as #5 millimeter
could be accurately ascertained. The subject was care-
fully instructed to remain as quiet as possible, but with-
out constraint. Voluntary movements were thus ob-
viated. But the question arose: were not the involuntary
movements thus suffering a loss?—And it was upon them
that we were experimenting. The question cannot be
put aside summarily, but experience taught us that the
movements in question, nevertheless, did appear quite
effectually, if one could have the right kind of subjects
at one’s command. We need hardly mention that besides
the two persons immediately concerned—I, myself, at-
tended to the apparatus—there was no one else present,
and that the subject was not allowed to see the curves
produced on the kymograph. Besides the registration
of the head-movements, I also undertook to register the
respiratory-movements of the subject. This was done
by means of the so-called pneumograph, attached to
which was a lever recording the thoracic expansion and
contraction. This was for the purpose of ascertaining
the relationship, which might eventually be found to
exist, between the release of psychic tension, on the one
hand, and respiration, on the other.

The subject was now told to think of some number,
which, of course, was unknown to me. At a given

118 THE HORSE OF MR. VON OSTEN

moment I was to tap upon one of a series of keys ar-
ranged like those of a piano, with the middle finger of
my right hand—corresponding to the right forefoot of
the horse. The questioner observed my key, I, his head,
—just what had happened in the experiments with Hans.—
and as soon as I perceived the involuntary closing signal
I reacted upon it by releasing, suddenly, another key
upon the same keyboard, which I had in the meantime
been pressing down with my second finger, thus marking
what with Hans had been called the backstep. Each key
was connected with a separate electro-magnet, and these
in turn with markers, in such a manner that pressure
upon the keys closed two electric circuits and, releasing
the keys, opened them, and both the closing and the
opening were recorded upon the smoked paper by means
of the markers. And, finally, in order to ascertain the
time relations of all these processes, a time-marker in-
dicated the time in fifth-seconds upon the revolving
kymograph record. The time-curve was recorded just
below the other curves.

Of the curves * thus obtained under the most equable

* For registering the curves a Hering kymograph was used, with a
loop 2} metres long. The kymograph rested on felt. With the aid
of the Marey model a pneumographic record was taken now of the
thoracic, now of the abdominal, breathing, never both simultaneously,
since this was extrinsic to my purpose, and it would have made the
whole experiment too complex. The time was recorded by means of
the Jacquet chronograph. For purposes of making more exact measure-
ments the acoustic current interrupter of Bernstein was used, attuned to
too vibrations per second. But this necessitated such rapid revolution
of the drum of the kymograph that the curves were not compact enough
for purposes of demonstration. The levers were all fitted with micro-
meter adjustments. They wrote tangentially and, except the one reg-
istering the breathing curve, all points lay in one vertical line. The
error of deflection and that due to the rondure of the writing-surface,

LABORATORY TESTS 119

conditions possible, we publish seven which show the
great general uniformity of the tests made upon the horse
with those made in the laboratory. The réle of questioner
was undertaken at different times by Mr. Schillings and
the students of philosophy, Messrs. von Allesch, Chaym
and K. Zoege von Manteuffel. To all of them I am
greatly indebted for their unselfish services in these labor-
ious tests. The experiments with von Allesch and Chaym,
who were among the most suitable of my subjects, were
conducted absolutely without knowledge on their part of
the nature of the phenomena which I was observing.
Neither of them knew anything about the expressive
movements in which they were unconsciously indulging,
and furthermore, since they kept their heads bowed during
the entire course of these experiments, they did not per-
ceive what it was that I was observing. It is interesting
to note that Chaym on the occasion of his only visit to
the horse, immediately received a number of correct
responses. Without a doubt von Allesch would have
met with equal success. The other two subjects (von M.
and Sch.) went through this series of tests, possessing
some knowledge of the nature of the movements involved.
Conditions were such that they (and especially Mr.
Schillings) could not be prevented from obtaining some

were both very slight on account of the comparative length of the
levers and the small extent of the excursions, and for that reason syn-
chronous points lie practically in one perpendicular. Only the breathing
curve has been moved somewhat to the left, 7.5 millimeters in figures 6
and 7, 2 millimeters in figure 8, 4.5 millimeters in figure 9. (When the
breathing was very profound, as occasionally happened, the error of de-
flection would, of course, have to be taken into account.) The curves
here used as illustrations have been reproduced in the exact size of the
originals by the zinco-graphic method, though somewhat compressed
vertically in order to economize space.

120 THE HORSE OF MR. VON OSTEN

knowledge of the essentials, at least. However, it would
be wrong to suppose that for this reason the results were
more favorable, owing, mayhap, to voluntary efforts on
the part of the subject. The contrary was true. The two
subjects who had no knowledge of the character of the
reactions upon which my responses depended, retained
their normal habits, unchanged, throughout the series,—
whereas the last-named two, afraid lest their knowledge
vitiate the result, lost more and more of their power of
concentration and within a short time were in a condi-
tion of tense inhibition, which is all the more conceivable,
since they had had no psychological training whatever.*

Their movements, which at first were quite profuse,
decreased more and more, so that in the case of von
Manteuffel the percentage of my successful responses
sank from 73% correct responses in 90 tests to 20% in a
total of 20 tests,—and in the case of Schillings from
75-100% to 23% in a series of 35 tests. The curves
obtained with von Manteuffel as subject, which I am
here publishing (figures 8 and 15), are, however, true
to his normal habits. The same is true of the two first
curves of Schillings (figures 10 and 11), whereas the
third (figure 12) shows distinctly the traces of the state
of inhibition into which he fell, and represents the same
condition as when Mr. Schillings, while preoccupied, tried
to work with Hans. All the finer details of the pheno-
mena in question, were likewise unknown to these two
subjects.

For purposes of a clearer understanding of the various

* My own expressive movements, on the other hand, are as pronounced
as ever. I still find the attempt to suppress them as difficult now
as when I was working with the horse (page 57). I could not, of
course, procure a curve of these movements of my own.

LABORATORY TESTS 121

curves, figure 5 is inserted to give the general scheme
of their arrangement.

Breathing

Head movements

Taps

Reaction

Al
&

Inhaling

Fifth-
seconds

= ae
uo
Le I

NH

eee |e

[pe Se ey

Pitt fii sit tp iti titisi tit

Fic. 5.

ee

{raciwant
ce
| down

| down

packstep

‘All curves are to be read like script from left to right.
The first is the breathing curve of the questioner, the
second, third and fourth curves represent his head move-

122 THE HORSE OF MR. VON OSTEN

ments,—all translated through the workings of the levers
into up-and-down movements. The objective direction of
these head movements is indicated by the arrows. It will
be noted that (because the lever in question was one
with two arms, and therefore reverses all movements
made) each lowering of the head of indicated by a rise in
the fourth curve, and each raising is the head is recorded
by a sinking in the same curve. The records of the head
movements forward and backward and to the left and
right (curves 2 and 3) are two and one-half times the
size of the actual movements; while the curve of the
movements up and down (curve 4)—which is of especial
interest to us—is five times its actual size. The fifth
and sixth curves, which record my own responses,
represent the taps of the horse,—the fifth indicating the
number of taps and the sixth the back-step, which was
Hans’s reaction when he noted the head-jerk of the
questioner. The seventh, the lowest line, indicates the
time in fifth-seconds. Since the rate at which the drum
revolved was not uniform for all the tests, the fifth-
second marks do not appear the same distance apart in
all the records, but are farther apart the greater the
rapidity with which the drum revolved. For the experi-
ment itself this is quite immaterial. Figures 6 to 9 cor-
respond in detail with the diagram just described.
Figures 10 to 12 differ only in that the breathing and
back-step curves (the first and sixth in the diagram) are
lacking. In these there is no response on my part to
the head-jerk of the subject, but tapping was continued
ad libitum (in the case of the illustrations here given I
tapped to 5). When these latter curves were taken the
ordering and the technique of the experiments had not
yet been perfected. When this was finally done, Mr.

LABORATORY TESTS 123

Schillings, who acted as subject in those tests, had to be
eliminated from the ranks of appropriate subjects on
account of the increasing inhibitions, which’ gradually
developed as described on page 120.

Analysis of such curves is rather difficult, and those
of different subjects cannot be directly compared. It is
necessary to make a study of the normal curve of each
subject taken when his affective state could be described
as “indifferent”. The influences of the purely physi-
ological processes, such as pulse * and respiration, must
also be determined. And even so, an interpretation of
the curve becomes possible only when a large mass of
material is at hand, and when the introspections of the
subject are taken into consideration. The following
remarks, therefore, are not based solely upon the illus-
trations given, but upon the mass total of my results.

In beginning our analysis, let us take first the breathing
curve. Our results here were quite in accord with the
view taken by Zoneff and Meumann,?° who believe that
in the respiration is to be found a good index of the
affective tone of the subject’s mental state. In the
greater number of cases it was possible to conclude as to

* Slight head movements accompanying the pulse-beat were until re-
cently regarded as the symptom of certain diseases of the vascular
system (the so-called symptom of Nusset), but H. Frenkel has now
shown them to exist also in normal individuals.!9 I myself discovered
such movements (lateral as well as sagittal) more or less pronounced in
all the curves obtained from my subjects. The most striking case was
that of a young physician whose circulatory system was perfectly healthy.
In most instances I was able to note these oscillatory movements
directly and to count them without much difficulty. For purposes of
control the radial pulse was always determined at the same time. The
observation of the phenomenon appears to be especially easy in the
case of somewhat full-blooded individuals.

124 THE HORSE OF MR. VON OSTEN

the degree of concentration of attention,—and when this
was very great, it was even possible to get a clue as to
the number thought of. Since the high degree of ten-
sion, under which a subject labored during a test, would
be accompanied by strong affective coloring, we cannot
regard as normal any of the curves here reproduced
(with the exception of the two high points in figure 9).
Although breathing was always deep and regular before
and after a test, during the test it was less deep and ir-
regular. Very often it was suspended altogether (figures
7,8 and 9g). In ordinary life we often notice that highly
concentrated attention is usually accompanied by non-
voluntary inhibition of movements in the musculature
which, for the moment, is not directly involved; the man
lost in thought slackens his pace and finally stands still,
the intent listener or looker-on holds his breath.

— Of the three curves registering the movements of the
head, we find that nothing peculiarly characteristic is
revealed by the two upper ones, giving the movements
up and down, and to the right and left, respectively.
They are the ordinary tremor-like movements and in-
dicate nothing beyond the fact that the subject is unable
to hold his head absolutely quiet for even one second.
It is the third line that is of interest to us, for it is here
that the oft-mentioned head-jerk (which indicates arrival
—in the counting—at the number expected) registers
itself. The moment of the head-jerk corresponds, almost
without exception, with the moment of the first deep
inhalation,—just as one would be led to expect from
common experience. But we are not to regard the head-
jerk as a result of the inhalation, for it also occurs when
the subject complies with the request that he hold his
breath during the test. The actual height of the jerks

LABORATORY TESTS 125

recorded in figures 6 to 12 was %4 to 1%4 millimeters and
the average height obtained from the forty curves of
these four subjects was 1 millimeter. There is great
individual variation: the greatest height that was ob-
tained from the records was 2,3, millimeters, the lowest
zy millimeter. The variations within the records of
the several individuals are comparatively slight and
are evidently dependent, in the main, upon the degree
of concentration of attention. Thus in the case of von
Allesch, where in 75 tests the average height of the jerk
is 1 millimeter, the mean variation is #5 millimeter. If,
in order to obtain some idea of the size of Mr. von Osten’s
movements,* we compared the values gained in the
laboratory with those which would probably obtain in
his case, we would say that his head movements were
more minute than almost any of those of which we
obtained records. At the most they could not have been
more than % millimeter (when measured in terms of
the distance through which the brim of his broad hat
moved, they would appear to be about 114 times as large.
See page 49.) The movements of Mr. Schillings, on
the other hand, were certainly four or five times as great
as those of Mr. von Osten, and occasionally even greater
than that. When we turn to consider the time-interval
elapsing between the subject’s final head-jerk and my
reaction (as recorded in the sixth curve), we find that

*In a special series of experiments a subject was instructed to exe-
cute rapid head movements as minute and as evenly as possible.
These were registered objectively and at the same time I made judg-
ments concerning them. The results showed that my judgments were
most exact in the case of the most minute jerks. The thing that made
it especially easy to judge the movements of Mr. von Osten under nor-
mal conditions, (page 220), was their extraordinary evenness, such as I
have not met with in any other individual.

126 THE HORSE OF MR. VON OSTEN

the reaction-time averages 35 seconds, a value which
agrees very favorably with that estimated for the horse

ALE dEt itd dd died diy ait

Fic. 6. Fic. 7.

(page 56). Thus it appears that man and beast have
the same reaction-time—though we must bear in mind

LABORATORY TESTS 127

that I worked under. some difficulty, since I had to care
for the apparatus.

Let us now turn to a discussion of the several figures.

Figure 6 (von Allesch) gives a typical view of the
great, and at the same time economic concentration of
attention characteristic of the subject. Respiration (first
curve) is not so profound as usual, yet is changed very
little. The head-jerk (fourth curve) is of medium height.
It occurs just at the proper moment,—the subject had
thought of 2, and had directed his attention economic-
ally. This attention was of the kind described as type I.
on page 93. The lowering of the head, (recorded in the
figure by a rise in the curve), immediately following upon
the head-jerk upward, is irrelevant.

In figure 7 (Chaym) we have a record of a different
nature. Respiration was inhibited throughout the test,—
(the small waves are due to the pulsating of the heart) ;
immediately after the test deep breathing takes place.
Tension steadily increased till 3, the number expected,
was reached. The head, accordingly, gradually sank a
little forward. The head-jerk ensued during an interval
beginning just before the reaching of the goal and ended
immediately after. The movement was predominantly
backward, its upward direction being only through a
distance of 4% millimeter. (This subject was not so
strongly motor, as the preceding one.) The reaction
followed promptly as seen in curve 6. It was the decided
raising of the head which follows the head-jerk, that
prevented the usual back-step with the left foot, when
the subject was working with Hans.

Figure 8 (von Manteuffel) is typical of strong and
at the same time economical concentration. Respiration,
normally deep and very regular, is for a time completely

128 THE HORSE OF MR. VON OSTEN

inhibited. Tension rises steadily and the head gradually
inclines forward. In the interval between the number

Fic. 8. Fic. 9.

before the final one and the final one the subject makes a
sudden bend forward and immediately upon reaching the

LABORATORY TESTS 129

final number gives a violent jerk of the head, upward.
The attention here would be characterized as being of type
III, described on page 94. (Owing to lack of space it is
impossible to give an example of type II, which is only
to be found in the case of very large numbers. )

Figure 9 (von Allesch) is expressive of great, but—
according to the subject’s introspéction—not economical
concentration. . Respiration, which before and after the
test was quite regular, during the test itself shows a

Sree ae

FIG. 10.

pause. (The tiny waves are due to the heart-beat.) The
subject had thought of 5, and this number is accompanied
by a decided head-jerk. But we note that even before
the final jerk a number of less pronounced jerks occur—
the result of poorly regulated psychic tension.

Figure 10 (Schillings) depicts a very high degree of
uneconomical concentration. There was sudden concen-
tration at the beginning of the test, and a steady increase
throughout its course. Accordingly Mr. Schillings bent

130 THE HORSE OF MR. VON OSTEN

forward at the start, and inclined still farther forward
at the second—and just before the third—tap. But
at 3 there is a sudden upward jerk. The number
thought of had been 4, tension therefore had exploded, as
it were, too soon.

Figure 11 (again of Schillings) gives indications, on
the other hand, of a medium and economic concentration
of attention, which is more normal in character. The
number thought of was 4.

Fic. 11.

Figure 12 (Schillings again) is indicative of a low
degree of psychic tension. With the very first tap the
head begins to rise and continues to do so throughout
the test. A true final jerk does not occur, we note rather
in all three curves registering the head movements, slight
time-marking movements, especially in the second curve.
In the third curve they are at first minute, but increase
steadily in size until the fourth tap, after which they
suddenly disappear. The subject had, as a matter of fact,

LABORATORY TESTS 131

thought of the number 4, but it is hardly probable that
Hans would have reacted properly upon these stimuli.

Mr. Schillings had thought of the same number in all
three tests given in figures 10, 11 and 12. The prob-
abilities are that if he had been working with the horse
at the time, in the first case Hans would have reacted
with three taps with the right foot and a final tap with the
left, as a result of the questioner’s bending forward again
after the premature head-jerk at 3. In the second in-

Fic, 12.

stance the horse would probably have given four taps
with the right foot, and in the third, the chances are that
he would have continued to tap beyond the 4.

These curves give, on the whole, a fair idea of the in-
tensity and of the course of attention of the various
subjects.

Let us now consider a number of records which illus-
trate the expressive movements involved in the process

“ce aT

of thinking of such concepts as “up”, “down”, etc.

132 THE HORSE OF MR. VON OSTEN

Their arrangement is identical with the scheme given in

figure 5, with the exception that the tapping curves (the

sixth and seventh) do not appear. The subject was asked
a” sé

to think of any of the words “up”, “down”, “right”,
“left”, “yes”, “no”, etc. He was to begin to conceive

FIG. 13.

them vividly when the command “ Now!” was given.
This moment is recorded in figures 13 to 15 on the fifth
curve. What has been said on page 123 with regard to
respiration, holds also; in these instances: only the first
rise recorded in figure 14 can be regarded as normal.

LABORATORY TESTS 133

The magnitude of these movements varies between 14
and 3 millimeters. The records of the subject whose
movements were most extensive, show an average of I7y
millimeter (based on 50 tests), with a mean variation of
i> millimeter. Lack of space precludes the reproduction
of more than three records.

Figure 13 (von Allesch) shows the movement accom-
panying the thought of “up”, a slight raise of the head,
recorded in the fourth curve. (The thought of “down”
is accompanied by a corresponding downward move-
ment. )

Figures 14 (von Allesch) and 15 (von Manteuffel)
illustrate the nod which is associated with the thought
of “yes” in the case of two subjects. It is essentially
the same in both: the head is lowered and then raised.
The first of the two subjects is more decidedly motor,
and his movements therefore were somewhat the more
extensive. In the case of the second subject the nod
proper is followed by another which is somewhat less
extensive.

A number of other experiments were carried out which
corresponded with the color-selecting tests made upon
Hans. (Page 78.) Five sheets of white paper, %4
meter long and 14 meter wide, were arranged in a series
upon the floor, 4% meter apart. A dot marked the middle
of each. The experimenter stood at a distance of 7%
meters and directly opposite the middle sheet. At about
y, meter to the right or left of him stood the subject who
took the part of the “horse”. The problem of the ex-
perimenter was to indicate to the “horse” a certain one
of the five sheets, but without the use of word or gesture.
I at first undertook the rdéle of “horse”, whereas the
others consecutively played the part of questioner. All

134. THE HORSE OF MR. VON OSTEN

of them looked fixedly at the sheet which they had in
mind. Besides, it usually happened that they would turn
at least their heads, and often their bodies, more or less

PR BSUSHEULOU OPEC NDREEBEE

Fic. 14. Fic. 15.

in the direction of the particular sheet—and this without
purpose or knowledge on their part, but purely as a
result of concentration upon the sheet they wished me
to point out. One of the experimenters remarked, quite

LABORATORY TESTS 135

casually, that he had noted that I always made a better
judgment, the more intently he thought of the sheet.
Others often admitted that, when I had made an error,
they had not imagined the sheet vividly, or had been
debating whether or not to decide to think of the neigh-
boring sheet—the one I had designated. This indecision
could be noticed by the direction of the eyes. But the
following table shows how uniform, on the whole, was
the behavior of the various persons when under the
guidance of the same impulse. The number of tests was
200 in each case. All errors were of the same character.
Neighboring sheets were mistaken for each other, and
the errors were never of more than one position to either
side. Their number can easily be obtained by subtracting
the percentage of correct inferences from the total,
100%.

Experimenter : v. A. B. C. Mrs.v.H. K. Miss v. L.
Correct inferences: 88% 88% 77% 81% 77% 82%

It will be seen that the number of correct interpretations
is quite high and in none of the cases does it deviate far
from the mean average of 82%.

I based my judgment as to the direction of the subject’s
eyes, upon.an imaginary line perpendicular to the center
of the cornea. (This perpendicular does not always
coincide with the subject’s line of vision, which was the
thing I was after, but this cannot be directly obtained.
This, of course, was what made the judgment a rather
difficult matter.) My judgment as to the direction of
the head I based largely on the direction of the nose,
(to express it more accurately: upon the direction of the
median plane.) I purposely noted only the position of
the experimenter and not the movement which led up to

136 THE HORSE OF MR. VON OSTEN

to it. When I tried to do the latter, the results were not
always satisfactory, because the head and eyes of the
person would frequently, in the process of adjustment,
move beyond the goal and thus lead me into error. An
attempt was made to make each judgment as independent
as possible of the preceding one. But usually, after a
few tests, an unintentional association became established
between certain attitudes and the different places in the
series of papers. Often all that was necessary was to
observe the experimenter in order to know which of the
places he had in mind, it was not necessary to look at
the papers at all. Every change in the position of the
person would, of course, make the association thus’ es-
tablished, useless.

Later, the subjects and I changed roles, I took the
part of the experimenter and they the part of the
“horse”. The number of tests in each case was 200
as before. Here, too, errors were, with but one excep-
tion, never more than of one place to either side.
Whether the error was one place to the right or one place
to the left appeared to depend upon the position of the
person making the judgment, i. e., it depended on whether
he stood at my right or at my left. The following results
were obtained:

Subject (“horse”): v. A. B. C. Mrs.v.H. K. Miss v. L.
Correct inferences: 76% 79% 75% 81% 77% 74%

A certain agreement can be seen in these results. The
average of correct inferences is somewhat lower than
that which was obtained by me (page 135), 77% as over
against 82%. This is probably due to the fact that the
“subjects had had so little practice compared with me.
With one of these subjects, Mr. Koffka, a student of

LABORATORY TESTS 137

philosophy, I carried these tests somewhat further, vary-
ing them partly by increasing the number of sheets of
paper, partly by decreasing the distance between them.
The increase in the number of sheets made only a slight
difference in the results. With 200 tests in each case I
obtained the following results:

No. of sheets 3 5 6 7 8 9 10
Correct inferences: 77% 72% 72% 60% 73% 68%

With but few exceptions, the errors were, as a rule, of
one place. The series with an odd number of sheets (5,
7,9) gave better results than those with an even number
(6, 8, 10). In the tests with the odd number of sheets
the experimenter (K.) stood in front of the middle sheet,
so that it was at the apex of a right angle made by the
series of papers and the median plane of the subject’s
body; whereas in the case of the even number of papers
the subject stood opposite the space between the two
middle sheets, thus making the position of the sheets less
favorable.

In the preceding tests the distance between the centers
of the neighboring sheets was always 50 centimeters, so
that the angle through which the median plane of the ex-
perimenter’s body would have to turn in order to pass
from one sheet to the next, was about 334 degrees. In
the following tests these distances were gradually
decreased. The sheets, always five in number, were
replaced by ever narrower white strips of paper mounted
on dark cardboard and illumined by a Nernst lamp.
The following table shows the decrease in correct infer-
ences running parallel with the decrease of the angle
through which the subject would have to turn in order
to be in line with the several pieces of a series succes-

138. THE HORSE OF MR. VON OSTEN

sively. The percentage in each case is based upon at
least 100 tests.

Angle: 3R° 3° 24° 2° 14° re
Distance between the
centres of two neigh-

boring papers : . §o0cm 39cm. 33cm. 26cm. 20cm. 13cm.
No. of correct inferen-
ces: ‘ ‘ , 77% 73% 71% 68% 66% 61%

A curious and unexpected change was here noted in
the subject, Mr. Koffka, who, while concentrating his
attention to the uttermost, began unawares to develop
a new system of expressive movements of the head.
When the distance between the sheets was relatively
great, he had been in the habit of turning his head and
eyes in the direction of the sheet intended, and as the
distances became less he had reacted only by a turning
of the eyes. But now, as the distances were still further
decreased, he began again to react. by means of head
movements, and these were of exaggerated magnitude,
for which he would compensate, as it were, by an eye-
movement in the opposite direction. Although the head
movements decreased in scope as the distances between
the sheets were steadily decreased, they still were always
decidedly greater than the eye movements, which I was
now normally led to expect and which could be judged
without much difficulty. This form of reaction was much
more satisfactory as a cue, and therefore it came to pass
that, whereas in the preceding series I had made only 60%
correct inferences when the angle was 1 degree, I now
found that—the angle remaining the same—80% of my
inferences were correct. (My final judgment I continued
to base, as before, upon the position, and not upon the

LABORATORY TESTS 139

movement, of head and eye). The number of correct
inferences continued relatively high, even after the dis-
tance between the papers was decreased tenfold,—as
will be seen from the following table:

o ,

Angle: . - © 30° i gf 7 C6 gs’ 3! 2’
Distance between th

centres of two neigh-

boring papers: . .131 65 33 20 15 13 1 6f 4mm.
Percentage of correct

inferences: . - . 8079 78 81 84 80 77 68 68%

Beginning with an angle of 1’ (distance between the
centers of two neighboring papers = 2 mm.), the sub-
ject was unable to focus, with sufficient steadiness of
vision, upon one paper alone, and the movements, for that
reason, ceased to manifest themselves. Comparing the
results obtained in the case of this subject with those
obtained from two others, whose reactions had remained
normal, B. and Miss St., we find that with them there
were only 53% correct inferences in both cases (based
each upon 200 tests), when the angle was 5’. In my
errors, too, I often shot wider of the mark. In another
series of 200 tests, in which Miss St. “ merely thought
of the places”, I had a percentage of 56% correct infer-
ences, and my errors did not become any coarser. Miss
St. believed this a case of true telepathy, but I had been
guided in my judgments entirely by her unwittingly
made movements—or rather the direction—of her eyes.
The magnitude of these movements bore a constant rela-
tionship to the distance between papers as it was con-
ceived by the subject.

Reviewing the experiments discussed in this chapter,
we find that the same kind of movements and postures,

140 THE HORSE OF MR. VON OSTEN

which had been ‘noted in persons experimenting with the
horse, tended to recur in the laboratory, in so far as the
mental attitude of the subjects, given in their introspec-
tive accounts, corresponded with that of the questioners
of the hosse:

CHAPTER V
EXPLANATION OF THE OBSERVATIONS

THE author having described the observations made
upon the horse, and having discussed the activities of the
questioner upon the basis of observations made object-
ively and upon his own introspections, and having veri-
fied the results thus obtained, by means of laboratory
tests,—we are now in a position to solve satisfactorily all
the problems which this interesting case has presented.

That which is least difficult to understand is the
horse’s seeming knowledge of language and particularly
“his ability to z answer questions, no matter by whom, or in
what dialect, they were put. As a matter of fact, it made
no difference who desired an answer, for the only person
upon whom the experiment depended was the questioner,
that is, the one who asked the horse to tap. We have
everywhere designated this person as the experimenter
or questioner. It was he who gave the directions, and
since all that were involved. were_visual signs, the drama
in which Hans appeared as the hero, was “nothing but a

pantomime, All speech was superfluous and, except
in so far as the tone of voice in which it was spoken
was soothing or reprimanding, it was quite unintel-
ligible to the horse.

From the foregoing, the reader understands without
further explanation Hans’s ability to count and to make
computations. If the number of taps had depended
solely upon the length of time and the angle at which

141

1442. THE HORSE OF MR. VON OSTEN

the questioner bent forward, the horse would have been
able to tap any number desired. Since, however, only
the right foot was employed, the left one being used at
most for making a final tap, the number of taps had an
upper limit which was due to the fatigue of the animal.
This limit was about 100. That it was possible to ask
such questions as: “ How many times is 100,000 con-
tained in 654321?”, and thus to give problems involving
millions, is perfectly clear. .

All wonderful feats of counting and computation which
were accomplished while thus experimenting with the
horse are to be accredited, not to the horse, but to
the questioner. If such is the case, they certainly cannot
be considered astonishing. Thus, when to the question,
“How many of the gentlemen present are wearing straw
hats?” the horse answers correctly in accordance with
the wording of the question and omits the straw hat of
a lady, then Mr. von Osten is the guide. It is no wonder
that Hans never showed the slightest excitement when
confronted with difficult problems, nor that it apparently
took no time whatever to solve them.

Hans, however, was also a faithful mirror of all the
errors of the questioner. Aside from mistakes due to
occasional interruptions on the part of visitors, these
errors had two sources: faulty computation and ina
_quate concentration—i. ey aie han arithmetical ao
~on the part of the questioner, were his premature or be-
lated movements. Since both of these factors might be
operative, the following three possibilities arise.

(a) The questioner computes correctly but does not
move at the proper moment. Nearly all the errors which
had been accredited to the horse, were of this kind.

A part of these errors had the appearance of being

EXPLANATION OF OBSERVATIONS 143

significant, that is, they might be interpreted as a mis-
_apprehension_of the question. If, for instance, instead —
of a sum only one of the quantities was given, or, if in-
stead of a product only one of the factors was given, it
might be interpreted that the horse simply wished to re-
peat the problem. Thus, Mr. von Osten in response to the
question : “ How much is 3 times 5?”’, twice in succession
received the answer, “3”, and upon my question, “ How
much is 3 plus 4?” he answered, “3”, and to “ How
much is 2 times 6?” he tapped 6, and to “ What is one-
fourth of 36?” 4. In part (certainly in the second and
third example cited) an individual quantity or factor
had been emphasized in the consciousness of the ques-
tioner (cf. page 105) and in part the reactions were due
to chance. Thus, when Mr. Hahn asked the question:
“What is one-half of 10?”, he received the following
responses: 2 and 10, and then 17 and 3. To this class
belong also, the tests made by the Commission of Sep-
tember and reported in Supplement III. (See page 255).
Other errors, even though they may not have appeared
to be significant, might yet have been characterized as
mistakes due to speed ; as when, e. g., Hans made an error
“of one unit—and sometimes, though less frequently, of
two units—too much or too little in his response. One
might be led to believe that Hans had not made an error
of calculation but merely of counting in the process of
giving his result, which always had to be done by the
cumbersome method of tapping. As a matter of fact,
the trouble lay in the wrong degree of concentration on
the part of the questioner: In errors of + 1, tension was
too slight, in those of — 1, it was too great (see page QI).
This comes out clearly in a comparison of the two more
extensive series which I took in the case of Mr. Schil-

144 THE HORSE OF MR. VON OSTEN

lings. During the first series, he was well disposed, and
was able to concentrate effectively, while during the
second, he was nervous and easily diverted. This dif-
ference in intensity of concentration in the case of the
two series is attested, not only subjectively by Mr. Schil-
lings’s introspective statement, but may be measured
objectively by means of the number of final taps which
the horse gave with his left foot during these two series.
We saw (page 94) that these final taps were always a
sign of intense concentration and, as a matter of fact,
one-half of the horse’s responses to Mr. Schillings during
the first series were made in this way; whereas, in the
second series, only one-third were of this sort. (I, my-
self, was never able to get, without conscious control, a
greater number of this type of response.) We may
therefore say that, in the first series we had a high degree
of tension, or concentration, whereas, in the second
series, we had a low degree. The errors distribute them-
selves over the two series as follows:

+1 +2 -1 —2
Series I (31 tests)
Correct responses : 87%
Incorrect “ : 0% 0% 13% 0%
Series II (40 tests)
Correct responses : 40%.
Incorrect “ : 40% 8% 2.5% o% (and 9.5%
other kinds of errors.)

We find in Series I no “ + 1” errors, but only “—1”
errors; in series II, on the other hand, the errors are
almost exclusively of the “+ 1” category, equaling the
number of correct responses, and there is only one
“— 1” error. A series obtained in the case of Mr. von
Osten is almost as satisfactory an illustration. When he

EXPLANATION OF OBSERVATIONS 145

first began to take part in tests in which the procedure
was the one we characterized as “ without knowledge ”
and had to note their complete failure, he was thrown
into such confusion that the responses in the case of
procedure with knowledge were also incorrect. The
errors there were always + 1, (whereas those in the case
of procedure with knowledge, which were due to quite
different causes, were very great and inconstant.) The
number of + 1 errors obtained on this occasion com-
prises one-fourth of all the plus errors which were ever
obtained in the case of Mr. von Osten during the entire
course of these experiments. Finally, I would mention
two examples of my own. In the course of my very first
attempts with Hans I obtained, as I said on page 89,
three responses in a total of five which exceeded the cor-
rect result by 1. This I would explain by the fact that
although I employed a high degree of concentration, I
nevertheless was somewhat skeptical. The result was a
certain deficiency in the degree of concentration. A
second example which I would cite is taken from the
period in which I had already discovered the cue to
Hans’s reactions and goes to show that I was then still
able to eliminate the influence of this knowledge and to
work ingenuously. To the question, “How much is 9
less 1?” I, momentarily indisposed, received the answer
10, and then six times in succession the answer “9g”, and
finally the correct response, “8”.

Errors of another kind—the not infrequent offenses
against the very elements of counting and the funda-
mental arithmetical processes—were regarded in part
as intentional jokes and by an authority in pedagogy as
a “sign of independence and stubbornness which might
also be called humor”. Hans emphatically asserted that

146 THE HORSE OF MR. VON OSTEN

2+2 was 3 or he would answer questions given in imme-
diate succession as follows: ‘How many eyes have
you?r—2. “How many ears? ”—42. “ How many tails?”
—z2. These errors, as a matter of fact, evince neither
wit nor humor, but prove incontrovertibly that Hans had
not even mastered the fundamentals.

_ Many of the errors baffle every charitable attempt at
interpretation. These gave the horse the reputation of
capriciousness and unreliability. If Hans designated the
tone “e” as the seventeenth, or “g” as the eleventh, or
when he called Friday the 35th day of the week or
believed 50 pfennige to be worth only 48, the cause for
these responses lay either in the insufficient degree of
tension on the part of the questioner (as in the first
three examples) or in the extravagant expenditure of the
same (as in the last case). If, therefore, the horse
at times would “hopelessly flounder ” which would seem
to be indicated by tapping now with the right and now
with the left foot, then as a matter of fact, this form of
reaction came about as was described on page 61, with
this difference that there we had to do with voluntary
controlled movements on the part of the questioner,
whereas here, they are the result of an unsuitable degree
of tension which expressed itself in frequent and dis-
concerting jerks. Besides the answer 3, this so-called
floundering was the only reaction the average person
could obtain from the horse in the absence of Mr. von
Osten and Mr. Schillings. It would however occur
also in the case of these gentlemen and would be re-
ceived by them with resentment when in truth it was
Hans’s greatest feat, for he showed his extremely keen
reaction upon every movement of the questioner. To
this group belong also the errors in the case of higher

EXPLANATION OF OBSERVATIONS — 147

numbers, the sole cause of which lay in the difficulty with
which tension cculd be maintained and the body kept
motionless for so long a period. These errors occurred
in accordance with a certain law. If, for instance, a cer-
tain test repeatedly evoked incorrect responses, the
questioner would gradually increase the duration of
tension and would thus come a little nearer to the desired
goal with every test. In this way, Mr. von Osten desiring
30 as an answer obtained consecutively the responses,
25, 28, 30; and I, myself, for the answer 20, received con-
secutively the responses Io, 18, 20 (see also the laboratory
tests, page 105). Sometimes too, the questioner would
flag in his efforts’before the goal was reached. Thus in
one of my first tests, I received for the answer 11 the
following responses: I, 4, 5, 7, 4. I was unable to get
beyond 7. In other instances, the horse responded first
with too few and then with too many taps. The correct
response therefore could only be obtained after an ap-
preciable amount of gauging of tension, as in target
practice there must be a gauging of distance. (See
page 92). In this way Mr. von Osten obtained for 10
the responses 8, 8, 11, 10, and Mr. Schillings for 17,
received 9, 16, 19, 18, 18, 14, 9, 9, and finally, after some
efforts, 17 taps. Thus there was a rise from 9 to Ig,
then a fall back to 9 and after eight tests the correct
response. As long as we attempt to explain this fact
as error on the part of the horse, so long will it remain
inexplicable, but the moment we regard it from the point
of view of the psychology of the tension of expectation,
it becomes perfectly plain.

The same holds true for the curious predilection which
Hans appeared to have for the numbers from 2 to 4,
especially for 3 (see page 68). As a matter of fact the

148 THE HORSE OF MR. VON OSTEN

cause of this lies in nothing other than the. inadequate con-
centration of attention on the part of the questioner and
less often in an extravagant expenditure of concentration,
which explodes immediately after the first tap on the
part of Hans (as in the case of my first tests) ; but usu-
ally the cause lay in a complete lack of concentration,
though the same result may be produced by various
causes. It is usually after 2 to 4 taps of the horse’s foot
that the questioner, who does not concentrate, makes his
first move which naturally puts an end to the tapping
on the part of the horse. As a rule this jerk follows im.
mediately upon the second tap. (On the other hand, re-
laxation of attention is very difficult upon the first tap.
See page 95). The questioner, however, would expect
further tapping and therefore would not bring his body
back to a completely erect position and the result would
be a 3, the last unit of which would be given by the
final tap with the left foot. Here we also obtained light
as to the answers which Hans gave in those tests in
which the method was that of “procedure without
knowledge”. These responses had nothing to do with
the problem, for neither the horse nor any one else knew
the solution. But in the horse’s responses the degree of
tension of the questioner’s concentration was faithfully
mirrored. An experimenter who was as skillful in con-
centrating as Mr. von Osten, obtained—almost without
exception—very high numbers, whereas one whose con-
centration was slight would receive in response to nearly
all questions the answers 2, 3 or 4. Thus, the Count zu
Castell received in response to seventeen questions the an-
swer 2, three times, the answer 3, six times, and the
answer 4, four times, two answers being accidentally cor-
rect,

EXPLANATION OF OBSERVATIONS _ 149

Another group of errors was characterized as_stub-
-bornness on the part of Hans, such as his persistence in
repeating an incorrect response, or his repetition of a
former correct answer in response to later questions
where it was perfectly senseless. During a demonstration
before a large number of persons, I held a slate with the
number 13 upon it within the horse’s view and also
within view of the spectators. I, myself, did not know
what number was written on the slate. Having been
asked to tap the number, Hans responded by tapping
5. The grand-stand shouted “ Wrong!” I asked Hans
to try again. Four times in succession he answered 5.
At another time Mr. von Osten and I each whispered a
number (7 and 1, respectively,) into the horse’s ear and
asked him to add the two. Three times in succession he
tapped 11. After the test had been repeated in accord-
ance with “ procedure with knowledge” and a correct
response had been received, we tried once more a test of
“procedure without knowledge”. Again, he responded
with an 11. On a third occasion, I asked Hans to tap 5.
He responded with a 4 and then, correctly, with a 5.
Thereupon, I asked him to tap 6. Again, he responded
with a 4. Then I asked him to tap 7. Once more he re-
sponded with a 4, and only when I proceeded to count
aloud did he tap 7 correctly. I had him repeat the 7 and
then went over to 9. Promptly he responded with an-
other 7. In these cases, which by-the-way were not very
frequent, we have to do, not with stubbornness on the
part of Hans, but with the persistence of that number
in the consciousness of the questioner. Modern psy-
chology has recognized this tendency of ideas, which
have once been in consciousness, to reappear on other
occasions even though they are wholly inappropriate.

150 THE HORSE OF MR. VON OSTEN

It has been termed “ perseverative tendency.” (Persever-
ationstendenz ” ).?*

While the errors thus far discussed appeared sporadi-
cally in long series of correct responses, there still might
be observed at times a massing of errors, usually at the
beginning of a day of experimentation or at the begin-
ning of a new series. We were regularly told that Hans
always had to have time to adjust himself to new cir-
cumstances. The records often showed comments such
as these: “After a number of practice tests the horse
appears particularly well disposed”, or “ Hans, at first
inattentive, does not respond. Suddenly he gets the hang
of things”. Different questioners who worked with the
horse required different lengths of time to obtain proper
responses. Some needed a quarter of an hour, others
scarcely half a minute. I, myself, found that in the
degree in which I learned to control my attention, in that
degree did this phenomenon tend to disappear, but would
reappear the moment I became indisposed. From this
we see that, instead of attributing all sorts of mental
characteristics, such as stubbornness, etc., to the horse,

_we should lay them to the account of the questioner. As
a matter of fact we find that this “ getting into the sweep
of things”, i.e. the overcoming of psycho-physical
inertia, has long been known in the case of man and has
been experimentally determined and called “ Anregung”
(excitation) by the psychiatrist, Kraepelin,?? and his
pupil, Amberg.?* A massing of errors toward the end
of a long series occurred only when the questioner was
fatigued. There was nothing which had to be interpreted
as fatigue or as indisposition on the part of the horse,
(except in the few cases of very large numbers, cf.
page 67). To be sure, Mr. von Osten always offered

EXPLANATION OF OBSERVATIONS | 151

these two excuses. That they were without warrant is
shown by the fact that Hans, after appearing indisposed
or fatigued while working with one questioner, would
nevertheless react promptly and correctly a moment later
for some other experimenter, and furthermore, when
working with me, the number of his correct responses
would rise or fall with my own mental disposition. _—--’

Finally, I would here note a rather interesting obser-
vation for which I am indebted to Mr. Schillings and the
Count zu Castell. They had noticed, independently of
each other, that the horse would often fail to react
when for any length of time he was given problems deal-
ing with abstract numbers, even though they were of the
simplest kind; but that he would immediately improve
They believed that Hans found applied mathematics more
interesting, and that abstract problems, or those which
were altogether too elementary, bored him. The Count
zu Castell furthermore noticed that the responses tended
to be more correct as soon as he had the horse count
objects which he, himself, (Castell) | could see during the
test. Quite in accord with this is the statement to be
found in the report of the September-Commission, in
which we find this note in a discussion of the arithmetical
problems (not involving visible objects), which the gen-
tlemen already mentioned had given the horse. “The
horse responded with less and less attentiveness and ap-
peared to play with the questioner.” Here again, that
was looked for in the animal which should have been
sought in the man. Mr. Schillings was capable of in-
tense, but not continued concentration and it was he who
was bored, and not the horse.” And it was the Count zu
Castell and not the horse that found it necessary to in-

152. THE HORSE OF MR. VON OSTEN

voke the aid of perceptual objects to bring his attention
to the proper height of concentration.

The reader will see that thus far I have supposed the
horse to be a never-failing mechanism and that I have
placed all errors to the account of the questioner. The
horse never failed to note the signal for. stopping and
therefore never was the immediate cause of an error. It
is not to be denied that now and then he would cease
tapping spontaneously and in this way would become
the cause of an error. We have no data on this point, but
undoubtedly the horse’s share in the total number of
errors was very slight.

(b6.) Another source of error was faulty computation
on the part of the questioner. The questioner made the
signal for stopping when the expected number of taps
had been reached. The horse faithfully mirrored the
miscalculation of the questioner. I have knowledge of
only one such case. The journals report that once Mr.
von Osten, when someone called to his attention that Hans
had indicated the wrong day of the week, replied: “ Yes,
you are right, it was not Thursday, but Friday,” where-
upon Hans being asked again, promptly responded cor-
rectly. This appeared to the reporter in question as proof
of the subjective influence of Mr. von Osten upon the
horse.

«~-(e.) When errors in calculation and failures in proper
| concentration combine, i. e. when the questioner makes a
‘mistake in calculation because he is excited or inatten-
tive and for the same reason does not make the move-
ment, which is the signal for stopping, in accordance
with the number which he deems to be the correct an-
swer, then the result is usually wrong, but it may be cor-
rect in the few cases in which the two errors exactly
compensate each other. Nothing has been so effective

EXPLANATION OF OBSERVATIONS | 153

in establishing Hans’s reputation, nothing has iedushe
him so many followers, as these cases in which he, rather_
than his mentor, has been in the right. Compared with
the mass of cases in which Hans was wrong these latter
eases are diminishingly few in number, yet these few
made such an impression upon the observers that their
number tended to be overestimated. As a matter of fact,
I have been able to discover records of only seven
such cases. Two of these were reported by the Count
zu Castell. On the 8th of September, he entered the
horse’s stall, alone, and believing it to be the seventh
day of the month, he asked Hans the date. The horse
responded correctly with 8 taps. At another time he
held up before Hans a slate on which were written the
numbers 5, 8 and 3 and asked the horse to indicate their
sum which in the momentary excitement, vaguely ap-
peared to Castell to be 10. To his chagrin he noticed
that Hans continued to tap. Thereupon he intentionally
remained motionless until the horse had stopped tapping
spontaneously—as he thought—at 16. (The newspapers
reported that the numbers to be added had been 5, 3, and
2; that the questioner had expected the answer 11, but
that Hans had in three tests always ceased tapping at
Io.) In both cases the questioner regarded the answers
of the horse as wrong and recognized his mistake when
his attention was called to it. I, myself, had the same
experience. One time I received in response to the ques-
tion, “ What day of the week is Monday?”, the answer
2, although I had expected the answer 1; at another time
I asked, ‘“‘ How much is 16 less g?”, and the horse re-
sponded with 7 taps, although I had erroneously expected
5. I noticed my mistake only when my attention was
called to it by one of those present. Another example is

134 THE HORSE OF MR. VON OSTEN

related by Mr. Schillings. A row of colored cloths lay
before Hans. Beside them stood an army officer. Point-
ing to the latter’s red coat Mr. Schillings asked the horse
to indicate, by means of tapping, the place in the row
where a piece of the same color lay. Hans tapped eight
times, but Mr. Schillings reprimanded him because the
red piece was, as a matter of fact, second in the row.
Upon a repetition of the test, Hans again tapped 8. (By
some, the facts are recounted as having been the other
way round; viz.: Hans tapped 2 instead of 8. This of
course would call for a different explanation.) It was
noticed that at the place which would be indicated by
eight taps there was not a red piece but a carmine colored
piece of cloth. A newspaper reports, somewhat vaguely,
a sixth case as follows: Hans was asked to spell the name
“Dénhoff” and began correctly: “D6”. Mr. von
Osten, who somehow began to think of another name,
“Dohna ”, interrupted him and wished to correct him by
suggesting o instead of 6 (i. e., 2 taps instead of 3).
Hans, however, “ continued to spell the entire word with
the greatest equanimity. He had not erred. A similar
experience is reported by Mr. H. von Tepper-Laski, the
well known hippologist. Although the details have
slipped from his memory, he reports that in the case in
question the correct answer was thrice refused by the
questioner who thought that the horse’s answer was in-
correct. Hans, upon being severely reprimanded in a
loud and harsh tone of voice, turned about as if disgusted
with the injustice of the man and made straight for his
stall—It is clear that in the cases described we are not
dealing with accidentally correct responses, for in nearly
every case the test was repeated a number of times and
_ the same responses were received each time. As a mat-

EXPLANATION OF OBSERVATIONS _ 155

ter of fact, my own introspection convinced me that the
third and fourth cases were surely, and the first and
sixth were very probably, due to insufficient concentra-
tion on the part of the questioner. Accordingly there is
everywhere in these cases a difference of + 1 or + 2 be-
tween the number thought of and the number tapped
(see page 92 f.). The data in the second and fifth
and still more in the seventh case were too meager to
warrant an attempt at explanation, for it is not even
known whether Hans responded with more or fewer taps
than was expected by the questioner. It is unfortunate
that a more complete record was not made.

The frequent and intentional attempts of Mr. von.
Osten to induce the horse to give an incorrect response,
—which, by-the-way, were regularly unsuccessful—be-
long only apparently to this group. Thus he asked, e. g.,
“2 times 2 is 5, is it not?” “3 times 3 is 8?”, etc., but
Hans refused to be misled, and responded correctly.
This was from the very beginning one of the main argu-
ments for independent thinking on the part of the horse.
The actual procedure was as follows, even though the
questioner had said “ 2 times 2 is 5”, there still was pres-
ent in his consciousness the number 4. I, myself, would
think either of the first member of the equation, i. e., 2
times 2, in which case Hans would respond with 4 taps or
I would have in mind the second member, i. e., 5, in
which case he would respond with 5 taps. Never did I
succeed ir thinking of both at the same time. The associ-
ation between the thought “2 times 2” and the concept
“4” is so close and supported by so many other associ-
ations that the attempt to form a new one, that is at com-
plete variance with all these, is futile. One may say
“2 times 2 equals 5” but it is impossible to conceive it.

156 THE HORSE OF MR. VON OSTEN

Let us turn now, from the tests in counting and compu-
tation to those in reading. We have seen that Hans
manifested his seeming knowledge of language symbols
in a threefold manner:|he might approach a slate on
which was written the symbol asked for,dor he would
indicate its location in a series of slates by means of tap-
ping, orfinally by means of so-called spelling of the
word which was written upon a slate or placard. The
responses by means of approaching a placard were very
often:unsuccessful, while indications by means of tapping
were scarcely ever unsuccessful. If it were true that
higher intellectual proceesses * were here involved, then
the converse would have been expected, for tapping re-
quired not only the ability to read, but also the ability to
count. If, on the other hand, we assume that the horse
simply followed the directions given by the questioner’s
movements, this seeming difficulty resolves itself, for it
would be more difficult for Hans to perceive the signs
which he receives while moving than those which he re-
ceives while tapping. When we recall that it was easier

* Professor Shaler 24, a well-known American savant, mentions 2
three-year old pig belonging to a Virginian farmer, that was able to read
and had some understanding of language. From numerals which were
written upon cards and spread out before it, this pig could compose
dates. It could also select from among certain cards one upon which
was written a given name, asked for by the master. Supposedly no
signs of any kind were given. (Shalerthought to exclude effectively the
sense of smell, which is so highly developed in the pig, in that he, Shaler,
himself smelled at the cards, since he also “ possessed an acute olfactory
sense!”) Since we are told that the farmer in question made a business
of supplying trained pigs for exhibition purposes, the case appears sus-
picious. We hear of a pig exhibited in London, that was able to read
and spell, and could also tell the time by the watch %. We cannot
tell, however, whether the two pigs, which beyond a doubt were mechan-
\cally trained to respond to signals, are identical or not.

EXPLANATION OF OBSERVATIONS — 157

to direct the horse to a placard near the end of a row
than one nearer the center (see page 81), we can
readily understand how it was that during the experimen-
tation carried on by the September-Commission (Supple-
ment III; page 255), Hans was able to point out immedi- :
ately the placards on which were written the names “ Cas-
tell” and “ Stumpf”, for they were at the two extreme
ends, but was unsuccessful in locating the one on which
was written the name “ Miessner”’ which was not a bit
more difficult to read, but was located at the fourth place
in the row. He first approached the fifth card, then upon
repetition of the test he pointed out the other neighboring
tablet, viz., the third.

In spelling, Hans was quite indifferent whether his
table with the eighty-four number signs upon it stood
before him, for he had no knowledge of letters. Neither
Mr. von Osten nor Mr. Schillings required it, for the
former knew the table by heart and Mr. Schillings told
me that before every test he made a note of the
numbers which were necessary to indicate the required
letters, trusting in this way to control the responses
of the horse and never guessing that by so doing
he was making it possible for the horse to answer cor-
rectly. The newspaper reports aroused much interest at
the time by stating that Hans was able to spell such
proper names as “ Pliiskow ” and ‘‘ Bethmann-Hollweg ”,
even to putting in the difficult “w” and “th”. The
friends of Mr. von Osten at the same time called attention
to the exquisite auditory acuteness of the horse which
enabled him to perceive the aspirated ““w” and to dis-
criminate between the “th” and “t”, (the “th” is
softer than the “t” in German.—Translator). This ex-

158 THE HORSE OF MR. VON OSTEN

planation, of course, must have appeared somewhat
daring even at that time.

Hans was quite guiltless of the many limitations im-
puted to him concerning his knowledge of symbols. That
he was unable to read capitals or Latin script was merely
a vagary of the master, like the belief that it was neces-
sary to confine one’s self in one’s questions to a certain
vocabulary and to a certain form. Mr. von Osten’s ap-
parent failure to elicit responses from the horse on topics

'of which it was ignorant is a beautiful illustration of the
| power of imagination. Mr. von Osten was convinced
from the very first that Hans could not answer such ques-
tions. When the belief in success was lacking, of course
there was not the requisite amount of concentration
which, alone, leads to perceptible expressive movements
and thus elicits a successful reaction on the part of the
horse.
“~Mr. Schillings, owing to his great impressionability,
remained long under the spell of Mr. von Osten’s point
of view. Thus I find in the record of the September-
Commission that the question “ How much is 3 plus 2?”
was answered incorrectly by Hans, but he responded cor-
rectly the moment Mr. Schillings replaced the word
“plus” which was “ tabooed”, by the word “and”. For
a long time also he could receive no response to ques-
tions put in French until one day he made the discovery
that, curiously enough, the animal never responded ade-
quately unless he himself firmly believed in the possi-
bility of success. It is noteworthy that the Count zu
Castell, independently of Mr. Schillings, made the same
discovery. Mr. Schillings made his curious discovery—
which he was unable to interpret, but which aroused some
suspicion—on the following occasion. One day—whether

EXPLANATION OF OBSERVATIONS 159

accidentally or because his prejudice was temporarily
overcome—he commanded; “Dis deux!”. Hans re-
sponded promptly with 2 taps. He was greatly sur-
prised and believed that Hans had gotten hold of the
French by hearing it spoken in his environment. Possi-
bly he understood also “trois” and “quatre”? He put
the questions and received correct responses. He asked
again, “dix”, “vingt”, and so on to “soixante”. At
“ soixante—six”’ he became doubtful. Indeed, Hans
failed him. At “ quatre-vingt”, the game began again.
“Cent”, again, succeeded. The old saying that “ Faith
will move mountains ” was verified once more.*

*It has been scientifically proven that a number of supposed mys-
tical phenomena, table-moving, table-rapping, and divination by means
of the rod, all are the result of involuntary movements made unawares
by those concerned, just as in the case of this work with Hans. (We
must of course except those not infrequent instances in which the phe-
nomena in question are purposely and fraudulently simulated.) There
is this difference, however, that there the thing affected is a lifeless ob-
ject,—the table or the rod,—here it isa living organism, the horse; hence
there the immediate effect of the movement is physical work in the form
of energy expended in moving the table, here the movement becomes a
visual stimulus. A number of observations which I find in the relevant
literature, and which I shall introduce into this chapter, may serve to
show how close is the similarity between the two cases, how much
depends upon the questioner, and how little really upon the instrument
—whether table or horse—which is acted upon.

Two examples will suffice to illustrate the significance of belief and
of the concentrated attention that results from it. The first is taken
from the letters of Father P. Lebrun on the divining rod %, which ap-
peared in 1696. An old woman once told a treasure-seeker that she had
always heard that a treasure was buried at a certain place in the fields.
The man, who was known as an expert in the art of using the divining
rod, immediately set out to locate the gold. Lo, and behold, the moment
he set foot on the spot described by the old woman, the branch turns
downward, and from its movements the man gathers that twelve feet
below ground there lies buried some copper, silver and gold. He calls

160 THE HORSE OF MR. VON OSTEN

Hans’s seeming knowledge of the value of coins and
cards, of the calendar and the time of day, as well as his
ability to recognize persons or their photographs, can
now be readily understood. In all of these cases, we had
to deal, in so far as knowledge is concerned, only with
that of the questioner,—the horse simply tapped the
number the questioner had in mind. The meaning which
was supposed to be expressed by the tapping never
existed as far as Hans was concerned; it was only in the
mind of the questioner that the concepts: ace, gold,
Sunday, January, were associated with “1”, etc. The
same was true with regard to all other wonderful feats
of memory. The sentence: “ Briicke und Weg sind yom

a peasant to dig a pit eleven feet deep, then he sends him away so that
no other should get into the secret. He himself digs a foot deeper, but
all in vain, for he finds nothing. Standing in the pit, he again takes up
the branch. Again it moves, but this time it points upward, as if to
indicate that the treasure had disappeared from the earth. Dismayed,
he climbs out of the pit and questions the branch a third time. This
time it points downward once more. He climbs back into the pit.
Presently he feels the prick of conscience (for in the 17th century many
regarded the dipping of the divining rod as the work of the Devil).
Terrified, he exclaims : ‘‘ O God, if the thing I am doing here is wrong,
then I renounce the Evil One and his rod (s’il y adu mal, je renonceau
démon et 4 la baguette”). Having spoken, he once more takes the rod
in hand to test it. It does not move. Horrified, for now there was no
longer any doubt that Satan was the cause of its movements, the man
makes the sign of the cross and runs away. But he had hardly gone
more than two or three hundred paces when the thought strikes him:
Ts it really true that the branch will no longer move for him? He
throws a coin to the ground, cuts a branch from a bush nearby, and is
overjoyed when he notes how it dips down toward the money.

Another example is to be found in a report of the well-known physi-
cist, Ritter °’, of Munich, which appeared during the early part of
the r9th century, Ritter, a man with a bent for natural philosophy and
metaphysics, describes an instrument which was to replace the divining
rod, and which he called “ balancier.” It was simple enough, consisting

EXPLANATION OF OBSERVATIONS | 161

Feinde besetzt”, (The road and the bridge are held
by the enemy), which was given to the horse one day and
correctly repeated by him on the following day, was not
an answer elicited from the horse by means of a question,
but rather a system of automatic reactions which were
induced by certain involuntary movements of the ques-
tioner as stimuli. Far from showing a wonderful
memory in these feats—as is claimed for him by the
very non-critical compiler, Zell *—-Hans, on the contrary,
has at his service a remarkably small number of asso-
ciations. For, besides possessing the powers of any
ordinary horse, he recognizes only a few meager visual
signs. To be sure, we find in the literature a horse that

of a metal strip that was balanced horizontally upon a pivot, and was
supposed to be put into motion in the presence of metals. Ritter used
this instrument in his numerous experiments with the Italian Campetti,
a man who had achieved a measure of fame in Europe for his ability to
discover springs and metals by the use of the divining rod. Carrying
the “balancier” on the tip of the middle finger of his left hand, Cam-
petti—whose integrity one cannot cavil at—had to touch repeatedly a
plate of zinc or pewter, and had to count aloud the number of touches
he made. The following curious law was found to obtain (that was
probably suggested to the subject by Ritter without his being aware of
it): with the first contact the “ balancier” turns to the left, with the
second to the right, and with the third it remains at rest. At 4 it turns
once more to the left, at 5 to the right, at 6 it remains at rest, etc. It
remained immovable only at the so-called trigonal numbers (3, 6,
9, 15, 21, etc.). Ritter tells us that when Campetti did not really count
or did not think of the number, then it would not have any influence
whatever upon the action of the instrument. This Ritter ascribes to
the agency of electricity (which in the 18th and rgth centuries was made
to play very much the same role that Satan had played in the 16th and
17th centuries).

The similarity of these two cases and that of Mr. Schillings is evident.
When the questioner of the horse and the bearers of the “ balancier ”
and of the divining rod are confident of success, they succeed. When
they do not expect success, they fail.

162 THE HORSE OF MR. VON OSTEN

was said to have recognized 1500 signals,”* but all proof
is lacking and the report is so meager that we cannot
discover whether these signs were auditory or visual.*

Having thus disposed of all questions concerning the
horse’s apparent feats of reason and memory, let us turn
to those in the field of sensation. We shall begin with
vision. That Hans was unable to select colored pieces
“of cloth merely upon the basis of color quality, without
reference to their order, was shown in Chapter II. It
would, however, be somewhat hasty to infer color-blind-
ness from this fact, as did Romanes ** on the basis of
similar unsucessful responses on the part of a chim-
panzee (“Sally ” of the London Zodlogical Garden). It
is much easier to explain the failure of the horse than
that of the monkey on the basis of intellectual poverty,
a poverty of associative activity. It presumably can
discriminate between the various colors, but it cannot
asociate with these their names. The existence of
‘chromatic vision in the lower forms is by no means as
unquestionable as is assumed by popular thought. Even
teleological considerations which are often brought for-
ward (especially that of the ornamental and protective
coloring of so many animals) can never do more than
establish a certain probability. For definite proof, we
need data given by observation (we have none in this
case), or experimental evidence. Such evidence we
have, but it is insufficient in quantity and unfortunately
most of it was obtained under inadequate experimental

* The French investigators Vaschide and Rousseau make a reference
to this case, and mistakenly state the number of signals as 1500 instead
of 115 ®, Ettlinger *! taks over this wrong figure and makes the
additional mistake of assuming that the reference is to an original inves-
tigation made by the two Frenchmen.

EXPLANATION OF OBSERVATIONS 163

conditions.* We know nothing regarding chromatic
vision in the horse, though we have often had trained
horses which apparently possessed color discrimination.
The earliest report of this kind I find in a work published _
in the year 1573.9 Here we read that a number of
Germans exhibited two horses in Rome which could,
upon request of their masters, point out those persons
among the spectators who were wearing stockings of
any designated color. The passage, “ conoscevano i
colori”, (they recognized the colors,) proves nothing and
no one has ever heard, even in modern times, of a horse
that actually knew colors. 4
Nor did Hans possess anything like that high degree -
of visual acuity which had been attributed to him. He
was supposed to be able to read easily at a distance small,
almost illegible script, which we ourselves could decipher
only with the greatest difficulty close at hand. It was
also supposed that he could distinguish ten- and fifty-

* All told, there are hardly more than half dozen experimental inves- ‘i

tigations of the color-sense in mammals,—to speak only of these.

‘Three of them deserve especial mention. One, the work of the Amer-
ican, Kinnaman, ® on two Rhesus monkeys. Then a brief but careful
piece of work by Himstedt and Nagel.84 These two investigators were
able to determine that their trained poodle could distinguish red of any
tone or shade from the other colors, and from Professor Nagel I learned
that later the tests were extended and the same was shown to be true
concerning the blue and the green. And finally there is an investiga-
tion which hitherto has been known only from a reference which Pro-
fessor Dahl,5 the investigator, himself makes. The work is on a mon-
key, Cercopithecus (Chlorocebus) griseoviridis Desm. (Professor
Dahl has kindly allowed me to look over the records of the experi-
ments. He intends to publish the monograph at an early date.)

All of these investigators arrive at the conclusion that the animals
tested by them possess color-sense. The monkey last-mentioned shows
one peculiarity : it was unable to distinguish a saturated blue from the
black. It will require further tests to clear this up.

164 THE HORSE OF MR. VON OSTEN

pfennig pieces whose faces had become worn beyond
recognition for us. None of these accomplishments have
stood the test. We havé iio" reason to“bélieve that Hans
can see the objects about him more clearly than other
horses, regarding whom one usually assumes that they
receive only vague visual impressions. Horses do not
as a rule seem to be near-sighted as is often asserted by
the layman, but rather somewhat far-sighted, or if we
‘may believe Riegel,” who tested some six hundred
horses, they probably have normal vision. But we are
told that many horses—and according to some authors all
—have an innate imperfection which detracts con-
siderably from the clarity of vision. This imperfection
-consists in an irregular formation of the sclerotic coat
and of the lens of the eye.* The two organs do not have
“the same refraction in all parts. As a result, objective

Mae arr . .
points aré not imaged as points upon the retina. (Hence
the name: astigmatism, i.e., ‘‘ without points”, for this
disorder.) The retinal image of the object is not only
vague, but also distorted.*

Many will doubt whether with such imperfect images
an animal can react to directives so minute, as we have
asserted to be true in the case of Hans. In considering
this question we must distinguish between the directives
for pointing out colors and the directives for tapping and
for head movements on the part of the horse. In point-

* There is no justification for the wide-spread belief that the horse
which on account of the greater size of his eye (more correctly, on
account of the greater focal distance) receives larger retinal images of
objects than does the human eye, for that reason also sees objects,
larger than we do. Horses’ shying is often explained in this way. But
the conclusion just mentioned is erroneous. The retinal image is not
the perceptual image. It undergoes many transformations within the
nervous system itself.

EXPLANATION OF OBSERVATIONS © 165

ing out and bringing forth pieces of colored cloth there
is involved the perception of an object at rest, viz.:
the direction of the questioner who is standing quietly;
whereas in the case of responses by means of tapping the
stimulus is the horse’s perception of the questioner’s
movements. Now, the construction of the horse’s eye,
as described above, is not favorable for the perception
of objects (so-called acuity of vision). This may partly
account for the slight success of the horse in those tests;
in which he was required to select a piece of cloth of a!
designated color, in so far as these commands were not ‘
accompanied by calls or exhortations. Where human ~
observers averaged eighty per cent correct responses
(page 135), Hans, under similar conditions was suc-
cessful in only one-third of the tests. In his errors he
was also wider of the mark than were the human obser-
vers (page 82). The object perceived, to be sure, is
a large one, viz.: the questioner, and he at close range.
We must therefore consider more specifically what are
the determining factors that make for success or failure
of the response. {First of all, the innocent questioner
very often did not designate the direction with sufficient
clearness. Furthermore,iHans presumably was not
able to discriminate sufficiently between the direction of
the experimenter’s eye and that of his head, which two
directions did not always coincide. * Finally the horse’s
attention was often diverted, while he was running toward
the piece indicated, by the other pieces lying to the right
and to the left, and for this reason the addition of a single
Piece to the otherwise unchanged row of five pieces
tended to decrease greatly the chances of success.

The case is different with the perception of the direct-
ive signs for tapping, for nodding and shaking the head,

166 THE HORSE OF MR. VON OSTEN

etc., all of which require the perception of movements.
This is not necessarily more difficult on account of the
imperfect constitution of the tissues that serve for the
refraction of light. Some authors even aver that this,
facilitates the perception of moving objects. This view
was first advanced by the excellent ophthalmologist, R.
Berlin ** of Stuttgart. In arriving at this view he was
guided by the following considerations. The peculiar
form of astigmatism of the lens of the horse’s eye, which
Berlin has described as “ butzenscheibenformig ”,* be-
cause it appears in the form of a series of glossy concentric
circles around the lens nucleus, has the property of en-
larging the pathway (and with it the rapidity) of moving
retinal images. If we take a speculum by means of which
a view may be had of the interior of the eye, and fixate
a definite point on the retina of the horse, and then
make a slight movement of the head horizontally, we
find that the point fixated moves—apparently at least—
toward the border of the pupil. In a normally con-
structed eye this seeming movement will be in a straight
line, while in the eye of the horse, (according to Berlin),
its path is curved, and therefore longer. Berlin believes
that the same thing which here occurs in the case of this
merely apparent movement, must also happen when an
external moving object is imaged on the horse’s retina.
Its pathway, too, will be curved, and therefore longer, so
that if the head of Mr. von Osten moves past the animal’s
eye, then the image on the horse’s retina will take a
longer, more circuitous route than it would if the eye

* “Butzenscheiben ” are the small circular panes of green glass, used
in leaded windows in early days. They are -high in the middle (hence
the name: “ Butze,” a protuberance) with a number of concentric circles
around the central elevation.—Translator.

EXPLANATION OF OBSERVATIONS _ 167

were not astigmatic. We cannot, however, immediately
conclude from the fact that an objective movement is
imaged as being greater in extent on the retina, that it
will therefore be more readily perceived by much less.
that it will appear greater to, the horse, than would
be the case if the lens were normally constructed. The
visual percept is not immediately dependent upon the
retinal processes, for between the two are interpolated
complex, inaccessible nervous processes. Still, Berlin
believes that he is justified in drawing this conclusion
from a number of relevant considerations. Accepting
it, he believes that it would be possible for the horse to
perceive movements, that for the human eye, which is
not subject to this form of astigmatism, would lie below
the threshold.

This theory, the simplicity of which certainly must
make a strong appeal, has been adopted by a number of
well-known investigators (Schleich *°, Konigshdfer **).
If we also could accept it, then Hans’s phenomenal power
of perceiving the movements of objects would be ex-
plained. But doubts arise which restrain us. Even if
we were to accept Berlin’s view in general, we should
still come upon the following difficulties. \In the first
place, it is questionable whether the peculiar form of
astigmatism mentioned is indeed as common as he sup-
poses.* The references in the literature are exceedingly

* Since no opportunity was given us to examine Hans’s eyes we do
not know what their condition is in this respect. Though it would have
been interesting to know, it would hardly make any difference in the
views presented. If Hans should prove to be either far or near-sighted,
then, if we are to make any supposition at all, it would be that the defect
could not be very great, since near-sightedness exceeding 2 or 3 diopters
and far-sightedness exceeding one diopter is seldom found in the case of
the horse. According to Mr. von Osten, Hans at one time manifested

168 THE HORSE OF MR. VON OSTEN

meager on this point. In order to make a few tests at
least, I undertook to examine nine horses with the aid of
Dr. R. Simon, oculist, to whom I am greatly beholden
for the assistance given in these and other tests to be
mentioned presently. In not one of the nine cases did
we discover anything like the curved deflection which is
supposed to be the sign of the form of astigmatism in
question. But in order to test objectively whether Ber-
lin’s assumption were justified, we examined in the
laboratory fresh specimens taken from two horses. The
eyes were fastened in a frame in what corresponded to
their normal position. Their posterior spherical wall
(i. e., their respective retinal surface) was replaced by a
piece of ground glass. On a spherical surface linear
movements of a point of light are always imaged as
curves, no matter what the shape of the lens forming
the image may be. (For a more detailed statement see
page 170, at close of note.) Since, however, our inves-
tigation had to do only with those curves which were
due to the qualities peculiar to the lens, we had to replace
the spherical by a plane projection surface. In front of
the eye thus modified a strong light was placed at such
a distance that the image of it, produced on the im-
provised back of the eye by the cornea and the lens,
was a sharply defined point of light. Now, when the
source of light was moved, the point of light would also
move on the glass plate. Sitting at some distance behind
the eye, we observed the movements of this point through
a telescope. Thus we became witnesses of what happens
upon the horse’s retina when a moving object passes in

a tendency to shy easily. Be this as it may, for little could be concluded
from it, since in many extremely shy horses, no kind of visual imper-
fection can be discovered.

EXPLANATION OF OBSERVATIONS _ 169

front of his eye. Although we saw the point of light
move through relatively long distances both horizon-
tally and vertically, no sort of deflection in its pathway
could be noted. Berlin’s exposition does not hold true
for the eyes of the horses, either living or dead, which
were examined by us.

But in the case of some of the horses in whom Berlin
had seen the phenomenon for which we sought in vain,
he himself tells us, the deflection was very slight. In
that case, it would appear, no great advantage would
be gained along the lines indicated. But even assuming
the degree of deflection to be very great, his theory goes
to pieces on the very point it was supposed to explain.
A concrete example will make this clear. If Mr. von
Osten, standing two feet away from the horse, raised
his head % millimeter (which figure by no means rep-
resents the extreme values that were obtained), then in
the horse’s retinal image every point of the man’s head
would move through a distance of 0.0025 millimeter—
assuming the horse’s eye to be free from astigmatism
and assuming its focal distance to be 25.5 millimeters.
If, however, other conditions remaining the same, we
prestippose an extreme form of astigmatism, one in which
the path of the retinal image is not a straight line, but
is deflected into a semicircle, then each point would pass
through a distance of nearly 0.004 millimeter. If the
sensitive retinal elements have a diameter of 0.002 milli-
meter (as Berlin, somewhat inexactly, states), then from
two to four elements would be stimulated in case there
were no astigmatic deflection. But in case the deflection
did take place, it would not necessarily involve more
elements, as can be seen by making a simple graph; in-
deed we can imagine cases in which the circuitous path

170 THE HORSE OF MR. VON OSTEN

would involve even fewer elements than the straight
one. And finally, when the movement which the horse is
to perceive, does not occur in a straight line but in the
form of a curve, (which will generally be the rule),
then the astigmatism will tend in many cases to decrease
the curvature of the image’s path on the retina, and
sometimes even obviate it entirely. In all these cases,
on Berlin’s own theory, the perception of the movements
would be hindered rather than aided.*

* For the benefit of specialists I would say the following in addition
to the more general remarks just made. For the most part, the deter-
minations of refraction made on the eye of the horse are still rather
unreliable. In sciascopy there is a dispute among investigators con-
cerning ambiguous shadows, and in the use of the refraction-ophthal-
moscope no definite region of the eye’s background has been adhered
to by the various investigators. It appears that Riegel, whose diligent
researches mentioned on page 164 were published in rgo4, knew nothing
concerning the round area in the horse’s eye, discovered by I. Zitirn #? in
1go2. Also, if so great a degree of astigmatism is really the rule as is
emphasized especially by Hirschberg #3 and Berlin,“ then the simple
refractive index usually given—sometimes within a half diopter—
would be meaningless. Berlin 4 and Bayer*® believe the vagueness of
the retinal image resulting from the astigmatism, is offset by this: that
the oval pupil functions as a stenopaic slit. In view of the width of the
horse’s pupil this appears to me to be rather hypothetical.

Concerning Berlin’s theory of deflecting astigmatism I would say the
following: Of the two ophthalmoscopic signs mentioned as being
characteristic of this form of astigmatism,—the concentric circles and
the arcuate deflection of the pathway of the fixated points,—when there
is a movement of the eye of the observer (or of the eye observed), ac-
cording to Berlin the former is not so constant as the latter. So far as
I know, the concentric ring formation is mentioned only by Bayer“ and
Riegel,* and is said to occur principally in horses with myopic vision—
and hence, relatively, in a minority of cases. Judging from the particu
lars, we are inclined to believe that a case of “ Butzenscheiben ”—lens
reported by Schwendimann 48 is in reality a case of senile sclerosis.
Berlin repeatedly warns us against mistaking the one for the other.
The arcuate deflection, on the other hand, has not been mentioned else-

EXPLANATION OF OBSERVATIONS © 171

But to come now to the most pertinent objection. We
saw that Berlin’s whole train of thought rested upon the

where as a personal observation. In Berlin’s calculation ** of the in-
crease in the extent of the retinal pathway an ambiguity has crept in.
He says that “in the astigmatic eye there are stimulated 207 times as
many nervous elements as would be stimulated in the ideally normal
eye.” It ought to read “207 more” instead of “207 times as many.”
And this number holds only for the one case computed by Berlin, and
under the specific assumption that exactly “ times the normal number
of elements were stimulated (571 instead of 364). Therefore the gen-
eral statement which Bayer © makes in his text-book, that according to
Berlin's evaluation * 207 times more nervous elements ” are stimulated
in the astigmatic eye than in the non-astigmatic one, does not hold true.

Closing this note, a few remarks concerning the experiments made
by Dr. Simon and myself. All of the nine horses were tested for the
vertical image by means of the ophthalmoscope. In most cases Wolff’s
electric speculum was used. Atropine was not employed. For the
laboratory tests the adipose and the muscular tissues were removed
from the eye-ball and the rear part of the bulb cut away. The front
part, containing the cornea and the lens, was fastened over one opening
of a metal cylinder which was closed at the other end by means ofa
disc of ground glass. The whole, approximately as long as a horse’s
eye, was filled with a normal salt solution whose refractive index (1.336)
corresponds quite closely with that of the vitreous humor of the horse’s
eye. The pressure from within was regulated so that on the one hand
it was not dimmed and yet on the other there were no wrinkles in the
cornea. The source of light——the filament of a Nernst lamp——was
moved about in a plane 120 cm. distant from the eye and perpendicular
to the optic axis. It was moved through the point of intersection as
well as at various distances from it. Movement in horizontal and verti-
cal directions was in each case along lines 150 centimeters in length,
which would correspond to an angle of vision of not less than 64°. The
pathway of the imaged point was controlled by means of the cross-hairs
of the telescope. If in the same way we observe through the sclerotic
of an intact eye-bulb a point of light falling upon the retina and shining
through the sclerotic and choroid (which is not difficult when we use an
intense light), then to the observer its pathway will, of course, appear to be
deflected convexly toward the periphery,—and the deflection will appear
the greater, the farther the point of light is removed from the optic axis.

172. THE HORSE OF MR. VON OSTEN

assertion that it made no difference whether we regarded
by means of the speculum the seeming movement of a
fixed retinal point, or whether the image of an external
moving object is passing over the horse's retina. As a
matter of fact, however, these two processes are very
different from one another. In moving the mirror, with
its small opening we are looking through ever changing
portions of the horse’s lens,—testing it out, as it were.
The horse, on the other hand, sees with all parts of the
lens simultaneously, in so far as the lens is not covered
by the iris. The arcuate deflection, which is nothing but
a registration of the difference in the indices of refraction
of the different parts of the lens used consecutively,
might thus be formed for the observer using the mirror,
but never for the horse. For these reasons we cannot
conclude that the kind of astigmatism described can
really increase the horse’s acuity in the perception of
movements.

Since the light-refracting apparatus of the horse’s eye
does not offer a satisfactory explanation for the extraor-
dinary keenness of visual perception possessed by the
Osten horse, we must go a step further and ask whether
it may not perhaps be found in the part immediately
sensitive to light, the retina. That portion really would
seem to be adapted to the perception of movements of
minimal extent, and for this reason: it is more than three
times as great in extent as the human retina, and the
horse’s retinal images are likewise larger owing -to the
position of the nodal point. The cells of the retina that
are sensitive to light, the rods and cones, might therefore
be correspondingly larger than those of the human eye,
without thereby making the whole organ less efficient
than the human eye. But the most recent measure-

EXPLANATION OF OBSERVATIONS 173

ments *' have shown that the rods and cones of the horse’s
eye are more minute than ours. Assuming that, in the
case of the horse, as is presumably the case in human
vision, the transition of a stimulus from gne retinal cell
to the next already in itself induces a sensation of move-
ment, then the horse ought indeed be extraordinarily keen
in the perception of moving objects (provided that the
horse’s more minute cells are packed just as closely as in
the human retina). And besides, there are two specially
adapted areas within the retina of the horse. The
“band” (streifenformige Area”) which was discovered
fifteen years ago by Chievitz,®? is a strip of 1 to 1%4 mil-
limeters in width, traversing the entire retina horizontally,
and is noteworthy on account of its structure and prob-
ably, too, on account of its greater efficiency. It may
have something to do with the accomplishments of the
Osten horse; but in how far it would be hard to say.
The other noteworthy portion of the horse’s retina is the
“round area”: discovered some four years ago, located
at the rear outer end of the “ band’’, and it is the best-
equipped part of the horse’s retina and corresponds to the
area of clearest vision, the yellow spot, in the human eye.
But this round area need not come in for consideration
by us, for its location would indicate that it is used in
binocular vision, that is, seeing with both eyes? But in
all our experiments the Osten horse observed only with
one eye. That does not mean, however, that under other
circumstances the round area may not be of very great
importance.

In the present state of our knowledge, all attempts at
explanation are, of course, of the nature of hypotheses.
If further investigations should disclose this explanation
to be untenable, then we would either have to suppose

174 THE HORSE OF MR. VON OSTEN

some unknown power in the eye of the horse,* or else
seek a cause in the animal’s brain. Further experiments
on other horses would be necessary in order to discover
whether the species as a whole possesses this ability or
whether only certain ones are thus endowed. The
former is of course more probable. In this particular
case conditions were unusually favorable for the develop-

* Konigshdfer, who as we have already said, seconds the explanation
given by the ophthalmologist Berlin (and who confounds “ Butzen-
scheiben” astigmatism with the common, so-called regular form), be-
lieves & that not only astigmatism but also the shape of the blind-spot of
the eye must be taken into consideration. This portion of the retina,
where the fibres of the optic nerve enter the eye (and called “ blind-spot ”
because there are no cells there that are sensitive to light) is very nearly
circular in man, but differs in shape in the different species of animals.
Kénigshéfer thought he had discovered that a relatively elongated blind
spot was favorable to keenness of vision. If we place the mammalia
in series on the basis of their relative keenness of vision, he says, we
would find that this series is identical with the one in which they are
grouped with reference to the form of the blind-spot from the circular
up to the most elongated. (In such a series the marmot takes the place
of honor.) %,

This exposition is not very satisfactury, however. We cannot be sure
what he means by “ keenness of vision ” (‘‘scharfdugigkeit”). Is it
visual acuity in the usual sense of the term (as is said in one of his pas-
sages), or keenness in the perception of the movements of objects, (this
would appear to be his real meaning), or both at the same time. But
whatever the significance he may put into the term, any such attempt
at grouping the lower forms must prove unsatisfactory from the very
start on account of the scant data which we possess on visual perception
in animals. The experiences of the hunt upon which Kénigshéfer
partly bases his view, are entirely inadequate for such a purpose. This
much is certain, that the Osten horse, in spite of a blind-spot which,
thought somewhat oval, is by no means very elongated, possesses an
extraordinary acuity in the perception of movements. Even if the par-
allelism: mentioned by Kénigshéfer were really shown to exist, it would
not explain the matter until it were also shown in what way keenness of
vision is dependent upon the shape of the blind-spot,—a portion of the
eye which is not immediately operative in the visual sensation at all.

EXPLANATION OF OBSERVATIONS | 175

ment of this ability. We must bear in mind that in all
probability Mr. von Osten’s movements very gradually
became as minute as they are now, and that therefore
Hans at first learned to react to such as were relatively
coarse. Furthermore, his practice extended throughout
four years and during this time it was his sole occupation.
Without specific predisposition, however, all this practice
would have been utterly futile. We can also readily
appreciate how indispensable in the struggle for existence
a well-developed power of perceiving moving objects
must be to horses (and most other animals) living in
their natural condition and habitat, in order to be aware
of the approach of enemies, or, in the case of carnivora,
the presence of prey. In view of all these considerations
we can readily see how it was possible that the horse,
perhaps in spite of rather defective vision, could react
with precision to movement-stimuli which escaped ob-
servation by human eyes.

We can understand also the horse’s never-flagging
attentiveness when we recall that self-preservation
prompts eternal vigilance over against all that is going
on in the animal’s environment. (In the case of Hans,
hunger was at first the motive; later, habit did the work.)
Furthermore, the lower form is not hindered in giving
itself over to its sense-impressions by the play of ab-
stract thought which tends so strongly to direct inward
our psychic energy,—at least, in the case of the cultured.

Nevertheless, Hans still remains a phenomenon not
only in excelling all his critics in the power of observa-
tion, but also in that he is the first of his species, in fact
the first animal, in which this extraordinary perceptual
power has been proven experimentally to be present. It
has long been known that horses could be trained to

176 THE HORSE OF MR. VON OSTEN

respond to cues in the form of slight movements, which
remained unnoticed by the layman, and this fact has
been made use of by circus trainers to its fullest extent.
But such signs, I have discovered, are without excep-
tion, of a far coarser sort than thosg.we have here de-
scribed, and they can be instantly detected by the prac-
tised observer. Nor was it known to professional trainers
that it was possible for the master to direct a horse to
any point of the compass simply by means of the quiet
posture of the body. For this reason it was believed
that no signs could possibly be involved in the color-
selecting-tests (cf. Supplement III, page 255). In this
we have the support of some of our experts, as is wit-
nessed by the following extract from a letter of his Ex-
cellency Count G. Lehndorff, one of our best hippological
authorities, who at one time carefully examined the Osten
horse. (The letter was addressed to Mr. Schillings, and
I have permission of both gentlemen to use it). In it he
says: “If the author’s statements, in which you also have
concurred, are correct, and if, as a matter of fact, the
horse really does react to such minute movements as are
absolutely imperceptible to the human observer, then we
have indeed something quite new, for hitherto no one
would have believed that horses can perceive movements
which man cannot. But I am even more surprised by the
explanation of the color-selecting feats— This too, is
something absolutely new. One would not have deemed
it possible that a horse could do anything of the kind
simply by using the posture of a man’s body as a cue to
which it could react with such precision.”

And yet, even though both facts were new concerning
the horse and had not hitherto been proven experiment-
ally regarding any other species, nevertheless something

EXPLANATION OF OBSERVATIONS | 177

of this sort has been known concerning the dog for some

time. His ability to single out an object upon which his

master had intently fixed his gaze, was made the basis of
a special form of training, called “ eye-training,” ®* nearly
one hundred ygars ago. The dog was taught to focus
~ constantly upon his master’s eyes and then upon com-
mand to select the object which he, the master, had been
fixating. Such a dog has been described by the natural-
ists A. and K. Miiller.5” But the master of the dog, unlike
Mr. von Osten, would not permit anyone else to work
with the animal, and the two brothers, recognizing the
trick, were justified in adding that “the whole affair
aimed at deceiving the public, and the dog’s reputation
was but a means of making money”. The success of
such exhibitions appeared furthermore, to depend upon
the close proximity of the trainer and the dog, whereas
the direction of the head (and even of the body) could
very probably be perceived at greater distances also.

At least we learn from a reputable source that in the -

hunt, dogs can perceive from the mere posture of their
master, what direction he intends to take.*®

But a still more curious fact is this, that dogs, too, learn
—evidently spontaneously—to react to the minimal in-
voluntary expressive movements of their master. The
first example mentioned in the literature on the subject
is that of an English bull-dog called Kepler, belonging
to the English astrophysicist, Sir William Huggins.®
We are told that this dog seemingly could solve the most
difficult problems, such as extracting square roots and
the like. The numbers were indicated by barking,—
thus one bark was for one, two barks for two, etc. Every
correct solution was rewarded with a piece of cake.
‘Huggins states explicitly that he gave no signals volun-

178 THE HORSE OF MR. VON OSTEN

tarily, but that he was convinced that the dog could see
from the questioner’s face, when he must cease barking,
for he would never for an instant divert his gaze during
the process. Huggins was unable, however, to discover
the nature of the effective signs. This satisfactory,
though still unproven, explanation has been accepted by
specialists, among them Sir John Lubbock.® I, too,
regard this dog as a predecessor of our Hans.

A similar case is reported by Mr. Hugo Kretschmer,
a writer of Breslau, in the ‘“ Schlesische Zeitung” of
August 21, 1904. To him I am beholden for a detailed
written statement, which he has kindly permitted me to
use in this connection. The gentleman named, first
trained his dog to ring the table-bell, and this, by press-
ing the dog’s paw upon the bell-button. When the dog
had learned to do this independently, his master tried to
teach him the rudiments of numbers, in such a way that
the animal was to give one ring of the bell for the num-
ber 1, two for 2, etc. But these attempts failed utterly
and had to be abandoned. But Mr. Kretschmer had
noticed that he was able to get the dog to ring any num-
ber which he, Mr. Kretchmer, might decide upon.
(Success was always rewarded by a bit of bread and
butter.) At first Mr. Kretschmer tried to imagine vividly
only the final number, but failed thereby to elicit correct
responses from the dog. But he did succeed when he tried
making a series of separate volitions. Thus for the num-
ber 5, he would “ will” each separate push of the button
on the part of the dog. Even so, however, he never got
beyond 9, for then the dog would become impatient and
would ring the bell continuously. Anything that diverted
the dog’s attention, such as noises, etc., also entailed
failure. In these tests master and dog had faced each

EXPLANATION OF OBSERVATIONS 179

other, each gazing steadfastly at the other. Mr. Kretch-
mer was convinced, however, that the dog was not
guided by any sort of sign, but rather by suggestion.
He based his belief on the following two observations.
After some practice, he says, the tests were also success-—
ful when he did not look at the dog, but stood back to
back with it, or when he screened himself from the dog’s
view by stepping to one side behind a curtain. The
tests were unsuccessful, on the other hand, whenever he
was mentally fatigued or had taken some alcoholic drink. ,
The arguments do not appear to me to be adequate. If
he turned his back upon the dog and no other observer
was present, he had no means of knowing whether the
dog did not, after all, peer around to get a peep at him.
If others who knew the desired number, were present,
the dog might have gotten his cues from them. And
there may be some doubt whether the curtain adequately
served the purpose for which it was intended. At any
rate, it was added that all attempts to influence the dog
from an adjoining room—which would thus exclude
effectively all visual signs—were utter failures. I am
also strengthened rather than weakened in my belief, by
the second argument which Mr. Kretschmer makes, viz..
that mental fatigue or the use of alcohol on the part of
the questioner tends to make the result unsatisfactory.
We noted a similar effect in the case of the horse (page
150), where a disturbance of the “ rapport” between the
questioner and the horse was invoked by some by way of
explantion. The facts were explained by us much more
simply. We attributed the result to the close correlation
between the type of mental concentration and the nature
of the expressive movements—a correlation which we
have shown experimentally to exist. I cannot, therefore,

180 THE HORSE OF MR. VON OSTEN

subscribe to the view that this dog did not require either
visual or other sensory signs. The tests which were
made for the purpose of strengthening that view, are on
a par, I believe, with those mentioned on page 45.
And since auditory, olfactory, and other stimuli, though
not impossible, still are improbable, I believe that out
Hans, Huggins’s dog, and the one belonging to Mr.
Kretschmer, differ from one another only in this, that
the first taps, the second barks, and the third presses a
bell-button.

And finally I have access to a letter from the Rhine
Province in which there is a brief account of a dog that
would promptly obey any command that was given with-
out a sound and supposedly without the accompaniment
of the slightest kind of gesture. It is specially mentioned
that the animal steadily watched its master during these
tests. The perception of the slightest involuntary ex-
pressive movements is in all probability the secret in this
case also. Here, too, suggestion has been invoked by
way of explanation, but there was not the slightest at-
tempt made to find for it a more specific foundation, and
we cannot suppress an objection based on the matter of
principle. It is incumbent upon anyone who uses a term
so ambiguous, to define what content he desires to have
put into it. If he does not do this, he is giving us, in-
stead of a concept, a bare word, instead of bread, a
stone.

While we must reject the explanation based on sug-
gestion,* we believe, on the other hand, that we have

* J can find examples of supposed suggestion in the case of animals
given only by Rouhet.*t He says that by means of suggestion he taught
a half-year old half-blooded mare-colt which he had raised himself, to
fetch and carry, and this in a very short time. In order to indicate to

EXPLANATION OF OBSERVATIONS © 181

here again, evidence of the presence of visual signs,
given unwittingly and involuntarily, just as I am sure
that they were involved in the two preceding cases, and
similarly in the case of the Huggins dog. Since the ef-
fective signs were discoverable in none of these canine
predecessors of Hans, an investigation would be desir-
able, based upon the insight gained as a result of these
experiments upon Mr. von Osten’s horse. Unfortunately
this is impossible, since the dogs in question are dead.
But others like them undoubtedly exist in many places.
We might mention that when Hans first came under the
limelight of public attention, there was also frequent
reference to the Huggins dog, but he soon dropped out

the colt what was wanted, Rouhet would concentrate with his whole
mind upon the object intended (a watch), and at the same time he would
bend forward slightly. In the third test, that is at the end of fifteen
minutes, he had accomplished his purpose, and in the tenth lesson, no
more mistakes occurred. The colt would fail to respond, however, as
soon as he refrained from making any gestures, or was in a laissez faire
frame of mind, or when he thought of other things. He therefore be-
lieves that there must have been some kind of immediate, though in-
explicable, connection between the brain of the trainer and that of the
horse. I think the explanation is evident: the connection was not as
he thought, an immediate one, but arising through the mediation of the
man’s attitude (“ attitude un peu baissée”), and of his movements
(‘gestes ”), both resulting from his intense concentration (“tension de
la pensée ”).

In general we may say that, no matter what content we may wish to
put into the term “suggestion,” not a single fact has since come to
light which would justify, and much less demand, the application of the
term to lower forms, unless we would expand the definition of the term
to the extent of comprising every kind of command, every arousal of
ideas, whatsoever. But it would then be nothing but a new name for
old knowledge ® and would lose all explanatory value. (Hypnotism,
so-called, in the case of horses, I shall discuss elsewhere in another’
connection.) a

182 THE HORSE OF MR. VON OSTEN

of the discussion again.** And this for two reasons.
The dog never took his gaze from his master and ap-
peared to be entirely dependent upon him in his reac-
tions. Hans, on the other hand, seemed to give evidence
of a high degree of independence and never appeared to
look at the questioner. But we know now that, though
he was never dependent upon the will of his master, he,
~too, abjectly hung upon the man’s involuntary movements
and never for a moment lost him from view. But since
the horse is able to observe with one eye alone, and
needed to direct only it and not the entire head toward
the questioner, in order to focus comfortably, one could
not conclude as to his line of vision from the direction of
the head. Since, furthermore, in the horse the pupil is
hardly distinguishable from the darkly pigmented iris
and since the white sclerotic is hidden by the eyelids,
except when the eye is turned very much, it is difficult to
determine what direction the eye is taking. I once pur-
posely stepped backward to the horse’s flank, so that he
had to turn his eye far back and thus the outer border
of the iris and the white sclerotic coat became visible
and all doubt concerning the line of vision was removed.
This doubt could never. arise in the case of the dog, the
median plane of whose head is always directed toward
the object fixated, and Zborzill is justified in saying, as
he does, in his discussion of training of the kind men-
tioned on page 177, “ But any careful observer can im-
mediately guess the manner in which such a dog has
been trained.” ** If Hans had chanced to possess so-
called “ glass-eyes”—in which the dark pigment is
wholly or partly lacking, so that, the black pupil is clearly
defined against the lighter background,—then no doubt
could ever have arisen concerning the direction of the

EXPLANATION OF OBSERVATIONS 183

eye, and Hans never would have come to be regarded as
the “ clever” Hans.

After the publication of the December report, Hans
acquired a reputation for excellence in thought-reading
and thus the discussion of thought-reading among
animals in general became once more the order of the
day. That is to say that many of our domestic animals
are—like the human mind-reader (a la Cumberland),
—supposed to have the ability to infer the thoughts of
their masters from slight involuntary movements. They
are thus aware when the feeding hour approaches, when
they may go out in the open, etc. They also appear to
be aware that their welfare lies in our hands, and there-
fore would seem to have a vital interest in divining our
intentions and our wishes. Not only our spoken words,
but also numberless movements—usually without our
knowing it and often contrary to our desire—speak a
clear language. As is well said by the American neuro-
pathologist, Beard, ®° (who first explained the phenom-
enon of thought-reading, on the basis of the perception
of very minute muscular jerks, and therefore called it
“muscle-reading” or “ body-reading”): ‘Every horse
that is good for anything is a muscle-reader; he reads
the mind of his-driver through the pressure on the bit,—
though not a word of command is uttered.” We know
that in the case of perfectly trained horses the rider’s
mere thought of the movement which he expects the
horse to make, is seemingly sufficient to cause the animal
to execute it.* Such cases are of course very much like

* An illustration is given by Babinet & concerning the horse of an
English lord. Mr. Burkhardt-Foottit, also, that excellent trainer, who
has been master for more than forty of the most highly-trained horses,
tells us that while sitting on a well-managed horse it sometimes hap-

184 THE HORSE OF MR. VON OSTEN

that of our Hans, excepting that instead of visual signs
they involve aids of a mechanical nature, which, however,
does not alter the general principle, since both of them are
of the nature of sensory stimulation, But we must not
overlook the essential difference between this so-called
thought-reading on the part of animals and that which is
done by man. The human thought-reader can interpret
movements, for he is familiar with the ideas which are
their source. Thus when at the second tap, I notice a
very slight jerk of the subject’s head, and a stronger one
at the fifth tap, I infer that he thought of the problem
2+3=5. While the experimenter thus cannot be said
to read thoughts, he still infers them. The animal, on the
other hand, we may be reasonably sure, draws no such
inferences. In its conscious life it remains ever on the
sensory level. If we could ask Hans about it, he would

pened that he had merely thought of making a certain turn, when the
horse immediately executed it, before he, the rider, had to his knowl-
edge given any sign or aid. An observation belonging under this head
is also made in Tolstoi’s “Anna Karenina”®’, this perfect mine of
acute psychological observation. In the famous description of the race
we are told concerning Count Wronskij riding his Frou-Frou just behind
Machotin mounted upon Gladiator, who was leading the race: “At the
very moment when Wronskij thought that it was time to overtake
Machotin, Frou-Frou, divining her master’s thought, increased her pace
considerably and this without any incitement on his part. She began
to come nearer to Gladiator from the more favorable, the near side.
But Machotin would not give it up. Wronskij was just considering
that he might get past by making the larger circuit on the off-side,
when Frou-Frou was already changing direction and began to pass
Gladiator on that side.” Similar experiences might be gathered else-
where. Not infrequently the reflection of the rider that his horse had
not for a long time indulged in some trick peculiar to him, will imme-
diately call it forth ; or doubts on the part of the rider concerning the
possibility of crossing some barrier, are often the cause of the horse’s
fall or of his refusal to leap and of his running away.

EXPLANATION OF OBSERVATIONS 185

probably answer: “ As soon as my master stoops forward, ~
I begin to tap; as soon as he moves, I stop. The thing
-which induces me to act thus is the carrot which is given
me; what it is that induces my master to make his move-
ments, I do not know.”—It is therefore erroneous to
believe that animals require the power of abstract think-
ing in order to utilize the signs which are consciously
or unconsciously given them, as is argued by Goldbeck
when he says with reference to the training for visual
signs, which we have already mentioned before:
“There the dog has consciously interpreted the visual
impression in terms of the conclusion that he is expected
to bring forth the leaf indicated.” Nor was there any
justification for the critic who thought he could put the
essence of the report of December, given in Supplement
IV, into the following words: ‘“ He (Hans) showed that
he has the power of attention, can draw logical conclu-
sions, and can communicate the result of his thinking,—
and all this independently.” Yet none of this had been
asserted. The whole thing may be explained satisfactorily
by means of a process of simple association established
between the signs observed in the master and certain re-
actions on the part of the horse. The fact that the move-
ments made were so exquisitely minute does not change
the matter in the least. Such signs call for a high degree
of sensory keenness and great concentration of attention,
but by no means an “ extremely high intelligence.”

Let us turn now from the consideration of visual per-
ception to that of auditory perception in the horse. We
saw that the fact that Hans was able to respond to com-
mands which were only inwardly enunciated, that is,
commands which were merely thought of but not spoken,
was not proof of great acuity of hearing, but rather that

186 THE HORSE OF MR. VON OSTEN

hearing was not at all involved. If Hans had been deaf
he would, none the less, havé promptly obeyed the com-

mands. Blind and near-sighted horses try to overcome
their deficiency by means of the sense of hearing, and
hence show a pronounced play of ears. In the case of
the Osten horse, however, attention has been diverted from
auditory stimuli in the process of habituation to visual
signs, and as a result ear-movements are almost com-
pletely wanting. One is not of course permitted to deny
a priori that perhaps some associations might have
been formed between objects and the vocal signs belong-
ing to them, e.g., between the colored cloths and the
names of the colors if both had been presented together
oftener than was the case.

But there is a dearth of reliable observation as to how
far auditory associations of this sort may be established
in horses. Usually the following is cited. Horses learn
to start off, to stop, and to turn about in response to calls.
They are able to distinguish properly between the ex-
pressions “right” and “left”, or equivalent terms.
Upon command they will start to walk, to trot or to run.
And they also know the name by which they are usually
called. All authors agree that cavalry horses understand
the common military commands; one writer even avers
that they excel the recruits in this respect. Some be-
lieve that in riding schools the horses pay closer heed to
the calls of the riding-master than to the control of un-
practised riders, even when the two are at variance with
one another." My experience with the Osten horse and
a number of other pertinent observations aroused in
me the suspicion that much that is called or spoken in
the process of managing a horse may possibly be just so
much labor lost. In consequence I made a series of

EXPLANATION OF OBSERVATIONS _ 187

relevant experiments. I have thus far tested twenty-five
horses of different kinds, from the imported Arabian
and English full-blood, down to the heavy draft-horse.
The experiments were made partly in the courtyard of
military barracks, partly in the circus, and partly in a
riding-school or in private stalls. I am specially indebted
for kind assistance to Messrs. von Lucanus, Busch, and
to H. H. Burkhardt-Foottit and E. Schumann, the two
excellent trainers connected with the Busch Circus.
During these tests, the horses were always amid circum-
stances familiar to them, whether free or bridled, under
a rider or hitched to a wagon. All aids or signals, except
the calls, were eliminated in so far as it was possible.
The results of those tests were in substance as follows:
Many horses react to a smack of the lips by a rather fast
trot. Many stop on the cry “Hola” or “Brr”. This |
last was nicely illustrated in the case of two carriage,
horses supplied with large blinders and held with a loose |
rein, and hitched to a landau. One of them regularly
stopped when the “brr ” was given by the driver, )
whereas the other, which had not been habituated to this |
signal, kept serenely on the trot, so that the vehicle’
regularly veered off the track—a sure sign that no un-
intentional aid was being given by means of the reins.
Other horses, again, were accustomed to halt in response
to a long-drawn-out “hola”, but it was the cadence of
melody rather than the word that was effective, since
any other word, or even a series of inarticulate sounds,
would produce the same result, provided they were given
with the proper inflection. When this was changed, then
the response would fail. Suu
The result was not so apparent when it came to con-
trolling the kinds of gait. One riding-school horse, when

188 THE HORSE OF MR. VON OSTEN

lunged and in a gallop, could be induced by a friendly
call—_the word again was a matter of inconsequence—to
slacken his pace into a trot and from a trot into a walk.
But this reaction was by no means very precise. Another
a full-blood, contrary to the trainer’s expectation and to
his great astonishment, failed to respond to any kind of
, spoken command as soon as the one who carried the
’ reins refrained from making any movements which might
indicate what was wanted. (To refrain from all ex-
pressive movements of this kind is by no means an easy
matter). The slightest move, apart from any help by
means of the reins or the whip-handle, was sufficient to
evoke a response. The results in the case of the military
horses, differed in many particulars. Thanks to the
courtesy of Captain von Lucanus I had the opportunity
of testing three cavalry horses, two geldings and one
mare, aged nine, thirteen, and nineteen years respectively,
and all of them in the regiment ever since their fourth
year. They had been selected as the “ most intelligent ”
in the squadron, and we were assured that they would
obey punctiliously all the usual commands. They were
ranged behind one another, with the customary distance
of two horses’ lengths between, and were ridden each by
his accustomed rider. Both starting and stopping upon
command were tested. The horses were held by the
reins, but the riders were cautioned to refrain from giving
any aid that might cause the horse to start when starting
was to be tested, or that might restrain him when stop-
ping in response to the spoken command was to be tested.
If a suspicion arose—a thing which happened only twice,
however—that a rider had actively aided in his horse’s
reaction, then an officer would mount into the saddle.
If it appeared that one of the horses was simply imitat-

EXPLANATION OF OBSERVATIONS 189

ing the others, then the others were purposely restrained
by their respective riders. The commands were given
by the corporal who usually had charge of the horses. In
a few cases the sergeant of the squadron gave the com- .
mands, but this made no difference in the success of the
experiment. Now as to .the results. Whenever the
horses were trotting or walking, all commands, without
exception, were in vain. They effected neither an in-
crease nor a decrease in the pace. A result was obtained
only when the horses were standing when the test began;
and this result was simple enough,—upon certain calls
the animals would respond by beginning to walk. . This
was the only reaction that was obtained. The most effec-
tive of the-comimands appeared to be “ Squadron,—
march!” But the command “Squadron!” or
“March!” alone, were quite as effective; yet none of
these commands was obeyed without exception. Reac-
tions were occasionally obtained in response to “trot!”,
“gallop!” “retreat!”, (the usual introductory “ squad-
ron” was purposely omitted here, because it alone suf-
ficed to start the horses). But the reactions were always
the same, viz., to start on a walk. Another series of
commands (such as those which are addressed to the
rider alone, e. g., “ Lances down!”’) had no effect what-
ever; a certain amount of selection therefore did seem
to take place. In all these tests the order of the horses
with reference to each other’s position was repeatedly
changed. One of the horses, the youngest, and reputed
to be the most “ intelligent ”, (he was as a matter of fact
the most spirited), gave evidence of a gregarious instinct,
‘intensified by habit, which, if it had been en overlooked,
might have become a source of serious error. Not being
accustomed to go at the head, when-se-placed it started

190 THE HORSE OF MR. VON OSTEN

properly in only 18% of all:such cases. When, however,
(other conditions remaining the same,) he was put in
second or third place, he started properly in 67% of the
tests, and if we take into account only those cases in
which the three most effective commands were used
(“ Squadron! ”, “ March!”, and “ Squadron—march!”)
he reacted correctly in 91% of the cases. (The number
of tests was 17, 36 and 22 respectively for the three
groups mentioned.) The horse, therefore, almost always
began to step properly when he stood behind one of his
companions, but seldom when he stood at the head. And
when he stood at the head and began to walk at the
proper moment, it was plain that it was a case of imita-
tion and not initiative, for the horse was still able to see
the others, owing to the extent of his field of vision back-
ward, and he was always the last to move, whereas other-
wise he was always the first to move, and always difficult
to restrain. So when the horses to the rear were re-
strained or when the intervening distance of two horses’
lengths was lessened, so that this gelding could not see
the one in the rear, he failed completely to respond. Ac-
cordingly these three horses did little to justify the faith
which their squadron had placed in them.
Now a few words on the manner in which horses react
(ozo the call of their names. We are not concerned
with those that are seldom or never called by name
(such as those in the cavalry). I have not discovered
one horse that constantly and unequivocally reacted upon
the mention of its name (though I would not assert that
there are none that would do so.) I was nearly always
able to convince the owners or grooms, who at first had
maintained a contrary opinion, that any inarticulate sound
was capable of producing the same effect as the calling

EXPLANATION OF OBSERVATIONS | 191

of the name. What the significance of inflection may be,
I am not at all certain. When a certain one of a number
of horses standing in the same stable was called, all of
them responded by pricking their ears, raising their
heads, or else turning about. For this reason the reac-
tion of the horse specifically called lost all significance.
Likewise the call which is ordinarily used in. lunging
when the man in the center of the circle wishes the horse
to change its gait, or to advance toward him, also proved
_ineffectual as soon as the man inhibited every sort of
_movement. A slight nod, on the other hand, was always
effective. Several times I have tried to call horses to me,
when they were free and running about in the arena, but
was unsuccessful. After I had given them some sugar,
however, they would always come to me—whether I had
called or not—and would then refuse to leave my side.
But this is a matter of common observation.

I would, however, regard all of these tests as merely
provisional. In spite of the greatest effort, it was not
always possible to control all the conditions of the ex-
periment, and furthermore, the number of tests would
have to be materially increased in order to yield an
appreciation of the difference due to race, age, and the
individual variation and training of horses. But we
may, even now, be sure of one thing. Over against the
certainty with which horses react to visual stimuli (in
the form of movements perceived), it does not appear
that the formation of auditory associations is greatly
favored by_ nature in these animals,—indeed, auditory
associations - are far less common than is generally SUP
posed. ed.* Horses compare very unfavorably with dogs in

Pa

* All the siithone who have given practical suggestions for the train-
ing of horses, whether free or with lunging reins, have great faith in

192 THE HORSE OF MR. VON OSTEN

this respect. The latter easily learn to react with a high
degree of precision to auditory signs,—as I learned from
a series of experiments which I was enabled to perform.
The Osten horse, therefore, does not stand alone among
his kind in his inferior auditory equipment, as one might
be tempted to believe at first blush.

the efficacy of calls, but usually recommend a mingling of calls and
movements in the way of signs, (thus Loiset,"! Baucher,”? von Amim®),
It therefore cannot be stated just in how far the calls really effect any-
thing. In other cases I am inclined to doubt outright the influence
which is ascribed to the auditory signs. Meehan7* gives an account of
a horse that was exhibited in London in the early go’s of the last cen-
tury. Pawing with his hoof, this horse apparently was able to count
and answer questions in arithmetic, and among other accomplishments
he was supposed also to be able to understand something of language.
In reality, however, he merely responded to cues which were disclosed
to the reporter by the trainer. In pawing, the horse was guided by
movements of the trainer, and in nodding or shaking the head he repu-
tedly got his cue from the inflections of the man’s voice. Is it not prob-
able that in this latter case it was the movements which accompanied
speech that were alone effective in inducing the nod or the shake of the
head, so that the exhibiter was deceiving not merely the public, but also
himself? Perhaps we may also doubt the exposition made by the well-
known hippologist, Colonel Spohr.% He tells us that it is easy to train
horses to raise the left foot or the right foot in response to the com-
mands “ Left—foot!” or “ Right—foot!” and that it will be the fore
foot when one is standing in front of the horse, and the hind foot if one
stands near the rear. It cannot be so very difficult, he thinks, even to
get the horse to understand the commands “ Left (or right)—fore foot!”
and “Left (or right)—hind foot!”—and all without any other aids
but the spoken words. Should this really be possible without even
the slightest kind of designating movement ?——The following case,
again, I believe is undoubtedly based upon a misinterpretation. Red-
ding” relates concerning his nineteen-year old horse that he himself had
owned for thirteen years, and had always kept in single harness, —
that this horse not only understood the meaning of a long list of words,
such as: bureau, post-office, school, churchyard, apple, grass, etc.,
but he also knew a number of persons by name, as well as their
places of residence. If he were told in advance to halt at a certain resi-

EXPLANATION OF OBSERVATIONS _ 193

It is easy to explain the musical accomplishments. The
tones which were played for the horse, were known to
Mr. von Osten, since he himself played the harmonica,
or when someone else played it, he, Mr. von Osten,
could see the stoppers. He then thought of the number

dence, he would do it without any further aid from the driver. For
this reason the happy owner felt certain that the animal possessed a
high order of intelligence and “that this horse does reason.” What
sources of error were here operative, whether signs were given by means
of reins, or head or arm movements, could be determined only by a
careful examination of the case.

And finally we would exercise some reserve in entertaining the sug-
gestions for the acoustic education of horses which have come from
various sources. Colonel Spohr 77 whom we have just been mention-
ing, thinks that it would not be a difficult matter to get a horse
to respond with a walk to one smack of the lips, with a trot to two
smacks, and with a galop to three, and then he could be made to
slacken his pace once more into a trot in response to one long-drawn
“Pst!” and to stop in response to two, Others have gone even further.
Decroix,’* at one time leader in veterinary affairs in France, conceived the
idea of working out a universal language as regards the commands that
are given to horses, in the humane purpose of sparing them the whip.
He called it “ Volapiik hippique.” For the commands “go,” “ right,”
“left,” and “halt,” he suggests these: “ Hit” “Hal” “Hé!”
and “Ho!” respectively. From these it was possible to make
eight combinations, such as Hil Hi!” for “ Trot!” “ Hé! Hé!” for
“Left about ” (while the single “ Hé” was to mean “ Forward, to the
left!”) “Ho! Ho!” for “Back!” etc. Decroix thought that the
whole system could be inculcated in a very few lessons. He even had
a medal struck which was to be awarded to the driver or rider who
should first exhibit a horse, thus instructed, to the Société Nationale
d’Acclimatation de France (of which Decroix was president). Eight
years have elapsed since then, but we have heard of no one who has
earned the medal mentioned. In the future greater care will probably
be exercised in the putting forth of such suggestions, and two sources
of error may be guarded against, viz.: involuntary movements on the
part of the rider or driver, and imitation of the horses amongst them-
selves. (One horse, guarded by an experienced rider, may serve as
copy for ten others with inexperienced men in the saddle.)

194 THE HORSE OF MR. VON OSTEN

which indicated the tone in question, and Hans would
tap it. Thus arose the tale of the horse’s absolute tonal
memory. This tale gained much support at the time,
from an experience which has been recounted to me by
the well-known composer, Professor Max Schillings.
It shows more clearly than any other report how very
confused were the threads that had been spun in the whole
matter. In order to test the horse’s musical ability Prof.
Schillings played, let us say, three tones upon the accus-
tomed instrument. Complying with Mr. von Osten’s
_ wish, Prof. Schillings always indicated which three he
was about to play. The horse always tapped them cor-
rectly. In order to make a decisive test, Prof. Schillings
then played, without anyone’s knowledge, a note that was
in reality a third below the one he had indicated to Mr.
von Osten. Curiously enough, Hans tapped, as a matter
of fact, the number indicating the note that was actually
struck, and it was only in the third repetition and after
many exhortations on the part of the master “to have
a care”, that the horse finally tapped the number in-
dicating the note Mr. von Osten had in mind and which
in truth was the wrong one. This curious experiment
seemed to those to whom Professor Schillings commu-
nicated it, to yield conclusive evidence of the horse’s
absolute hearing. As a matter of fact, however, Prof.
Schillings had unwittingly, and, contrary to any inten-
tion on his part, inspired the horse. Standing, as he did,
just behind the right shoulder of the horse, he was able
to interrupt Hans (who had begun to tap in response to
a move on the part of Mr. von Osten,) by means of an
involuntary movement which did the work of a closing
signal. At the same time Mr. von Osten, likewise stand-
ing to the right of the horse and expecting more taps,

EXPLANATION OF OBSERVATIONS _ 195

remained perfectly quiet. (This is as it was in the tests,
mentioned on page 71, in which, of two experimen-
ters, one started the horse tapping, and the other stopped
him.) Mr. von Osten very probably lost patience after
Hans had seemingly given the wrong response twice,
and thereupon came nearer to the horse and thus by
monopolizing its attention—so as to exclude Prof. Schil-
lings—he was able to get the response so ardently
‘desired.* When, in tests such as these, two stoppers

* General Noizet 79 has left us a story of the middle of the last century,
which in essential detail corresponds closely with the one just given.
The scene is a French chateau and the hero is—a rapping table, highly
prized on account of the intelligent answers it could give. Seated about
it were a number of ladies and at the other end of the room sat a French
savant,a member of the Academy. The ladies requested him to put a
simple mathematical question to the table, and complying with their
request, he asked for the cube root of 4. None of the ladies who sat
about the table knew the solution; the table unhesitatingly gave 6 raps.
This answer was refused as incorrect. The table wasasked to try again,
and again it wrapped 6. For this it was bitterly reproached. Hereupon
the questioner, who during the whole time had remained in his place at
the other end of the room, came forward with the confession that the
table was innocent, that he had made a mistake. He had asked for the
cube root of 4, but had really meant to ask for the cube of that number,
viz., 64, and the table had as a matter of fact given the first numeral of
that number.

One is immediately struck by the analogy between this case and that
of Professor Schillings. In both cases those immediately concerned
(the women in the one, Mr. von Osten in the other) believe that a wrong
answer is being given repeatedly. The cause of the error lies in a per-
son who seemingly is not concerned with the response. (The French-
man asked the question, but did not sitat the table. Professor Schillings
sounded the notes, but it was Mr. von Osten who got the horse to tap.)
In both instances the questioner asks one thing, but had something else
in mind. (With the Frenchman it was a slip of the tongue; Mr. Schil-
lings did it purposely.) And finally, in both cases the response cor-
responds not to the question that has been asked, but to that which has
been thought, so that, though seemingly wrong, the responses of both

196 THE HORSE OF MR. VON OSTEN

were opened and thus two notes sounded, Mr. von Osten
would count the number of stoppers intervening between
the two, and Hans would tap the number. And so arose
the tale of Hans’s knowledge of musical intervals.
Whenever the two notes were sung or whistled, in which
case there would be no stoppers that could be counted,
then Mr. von Osten, who was quite destitute of musical
knowledge, was at a loss, and also Hans. If, however,
the intervening notes were sung, then everything went
smoothly once more. Major and minor chords were
regularly characterized as “beautiful”, all others as
“bad”, (but even here errors occurred). A musician
had taught Mr. von Osten these distinctions. The old
man also knew the melodies that were played on the
hand-organ. Each one had a number assigned to it, and
Hans was required to tap the number of the melody in
token of recognition——Hans was as ignorant of musical
time, as he was of melody ,and all attempts to get him to
march in regular step were utterly futile. A number of
musical tests were made in the absence of Mr. von Osten.
In these Mr. Hahn undertook the questioner’s réle, and

table and horse were really correct. By way of explanation, Noizet
believes that he has a case of true thought-transference or “telepathy”
(page 108). The questioner watched with utmost attentiveness the rap-
ping of the table, and the women in turn regarded the man. And thus,
Noizet believes, the man’s thought was transferred to the minds of the
others without the mediation of eye or ear, etc., and hence unvitiated by
the words that had been spoken. I myself prefer another explanation.
At that moment in which the rapping arrived at the expected number,
the Frenchman executed a movement characteristic of release of tension
and to this the women of the circle reacted. It was not necessary that
they should be able to account for this afterward, (just as sometimes
occurs in the case of thought-readers 8°), It is very probable, too, that
they were not of a very reflective turn of mind anyway. We are war-
ranted, I think, in regarding the two cases as identical in kind.

EXPLANATION OF OBSERVATIONS — 197

since he had had musical training, he was aware of what
the numbers should be, even when he could not see the
stoppers of the harmonica, and, therefore, we readily un-
derstand why it was that the horse responded so wonder-
fully in his case.

The so-called musical ability of horses appears, from
all that is known, to be confined within very narrow
bounds. Only one fact is universally accepted, viz.,
horses of the military are believed to possess a knowl-
edge of the significance of trumpet signals, and are often
_Said to interpret them more readily than the recruits.*
Since no ‘experiments had been made along these lines, I
undertook to make a brief test of the cavalry horses men-
tioned on page 188. As in the preceding tests, the three
animals were arranged behind one another with the cus-
tomary distance of two horses’ lengths between, and each
was ridden by his accustomed rider. They were held by
the reins, but received no aid of any kind, either to start
them or to restrain them. A bugle then sounded the vari-
ous signals at the other end of the barrack’s courtyard.
We had been previously assured that the horses would
certainly react without fail. But, as a matter of fact, the
result was quite the contrary. Two of the horses did not
move at all, and the third, a thirteen-year old gelding, was
startled nearly every time and would tear off in a gallop—
even though a trot had been sounded. I would not,
however, venture to draw any conclusions from results
such as these. Many more tests would have to be made,
and some of them upon the whole squadron, before a
judgment could be given.*

* Frofessor Fliigel,® basing his statements on an article appearing in
“ Schorer’s Familienblatt ” (Berlin, 1890, No. 8, p. 128), gives an account
of similar experiments which were supposed to have been conducted by

198 THE HORSE OF MR. VON OSTEN

__ I shall_now turn to peculiarities of character, highly
humanized, which have been attributed to Hans. His

“sympathies ” and “antipathies ”, so-called, were noth-
ing 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 noth-
ing 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

the Zoological Society for Westphalia and Lippe, and presumably
showed that “the horses of the military do not understand the bugle
calls.” No matter how well trained a horse may have been, it would
not respond to a signal. This report, however, is due to a mistake.
Such experiments have never been made by the society mentioned, soI
am told by its director, Dr. Reeker. Nor do I know of any one else
who has made experiments of this kind. However, Professor Landois,®
the eminent zoologist, now deceased (founder of the scientific society
mentioned), tested four circus-horses for their musical ability and spe-
cifically for their sense of musical time. He arrives at the conclusion that
horses “have no feeling for time, whatsoever.” With but few ex-
ceptions,®’85 all experts to-day are of the same opinion. Horse-trainers,
especially, are universally agreed on this point. It is easy to see in any
circus performance that it is not the horses that accommodate them-
selves to the music, but that the music accommodates itself to them,
and that the trained horses *® are induced to do their artistic stepping
only by the aids given by their riders. Furthermore, all these horses are
trained without the use of music. It would therefore appear that
the time had arrived when the tales of the dancing horses of the Sybarites
ought no longer to gain credence. Two Greek writers, Athenaeus ®
and Zlian,® tell us that the inhabitants of Sybaris, farfamed for their
luxurious habits, had trained their horses to dance to the music of flutes
during their banquets. Building upon this, the men of Crotona, in one
of their campaigns against the Sybarites, ordered the flute-players to

EXPLANATION OF OBSERVATIONS — 199

two thoughts were accompanied by the corresponding
head movements, to which Hans responded mechanically.
Hans appeared to be well-disposed toward me, but evi-
dently 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 them-
selves, were always ready to rebuke Hans for his con-
trariety 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 experimenta-

play the tunes familiar to the Sybarite horses. Immediately the well-
trained steeds began to dance, thus throwing the whole Sybarite army
into confusion, and the men of Crotona won the day. (The same story
is told in more detail concerning the horses of the inhabitants of Cardia.
Both accounts, somewhat mixéd, are to be found in Julius Africanus,®
a writer of the third century of the Christian era.)—In recent years a
French veterinary surgeon, Guénon,” experimented on the effect of
music upon the horses of the military. He entered their stalls, playing
upon a flute, and noted their behavior. Four-fifths of the animals, he
says, were deeply moved, yes, delighted, even, (““charmés.” One inter-
preter %! calls ita case of hypnosis!). This emotional excitement was
expressed—somewhat unaesthetically —by the dropping of excrementa.
Guénon characterizes the feeling-state of these animals as being a mix-
ture of pleasure and astonishment, of satisfaction and excitement
(‘mélange de plaisir et d’étonnement, de satisfaction et de trouble.”)
He also asserts that the horse’s musical taste is similar to ourown. But
I can find nothing in his whole exposition which might prove this. In-
deed there is nothing that could be interpreted as anything other than
a purely sensuous effect upon the horses. I may goa step farther and
say that thus far the sense of music, i. e., understanding of melody,
harmony and rhythm, has not been shown to exist in any animal. Some
animals may, however, be susceptible to the sensuous pleasantness of
the tones themselves.

200 THE HORSE OF MR. VON OSTEN

tion 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. Ex-
perts assure me that we have here to deal, not with a
case of “moral insanity”, but with a very common ex-
perience—although this view will probably be cavilled
at by enthusiastic. lovers of horses. The work of so
excellent an expert as Fillis,9? 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 dis-
appear 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 usu-

ally 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

EXPLANATION OF OBSERVATIONS 201

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?’”. Here-
upon Hans promptly shook his head, to the great merri-
ment of all those present. (Mr. Schillings had, with no

swered 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 noth-
ing but a poor attempt to account for the failure of those
tests. Hans’s distrust of the correctness of his own re-
sponses 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

202 THE HORSE OF MR. VON OSTEN

some form of approval or disapproval—just as a school-
boy 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 ques-
tioner 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

wa,

ginning 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 neces-
sary to touch upon the signs that were supposed to be-
token 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

EXPLANATION OF OBSERVATIONS — 203

the persons experimenting with him,* the first and most
important question that arises is this: How was it pos-
sible that so many persons (there were about forty) were

* T cannot enter upon a discussion of the latest psychological prob-
lems, here involved, partly because that would take us beyond the pur-
pose of this monograph, and partly because they are still moot questions
and hence not suited to popular treatment. Briefly though, they are
these : What is the nature of the relationship between cognitive and
affective states on the one hand and involuntary, (so-called expressive)
movements on the other? Is this connection an external thing, as it
were, an association arising as a habit formation, or does every idea
partake essentially of a motor character? Do purely cognitive states
give rise to such movements, or does the movement impulse depend
more particularly upon the affective consciousness accompanying the
cognitive states? And in how far do given kinds of expressive move-
ments depend upon certain ideational types (c.f. page 95)? Thus,
what is the influence of the visual image upon the gestures for “up,”
“down,” etc.? And then, are these involuntary movements, when not
noted, truly unconscious, or merely not attended to,—— in other words,
are they beyond the pale of consciousness or merely “at the fringe?”
The various writers speak almost without exception of unconscious
movements in the strict sense of the term. My own introspections, how-
ever, have led me to doubt whether they are quite unconscious. Since
I have attained some practice I am able to describe in detail (under
conditions of objective control) my involuntary movements, no matter
how slight, even down to mere muscular tensions. None of my sub-
jects, however, has as yet succeeded in this. It is no very easy matter
to be on the lookout for some unknown movements which might even-
tually occur, while attempting to concentrate attention to the utmost
upon a certain definite ideational content, for this very dividing of
attention effects a decrease in the force of the movement, and thus
makes it all the more difficult to discover. From my own experience,
however, I am inclined to believe that these movements are not uncon-
scious, but merely unattended to, in other words, we have a narrowing
down of the apperceived content within certain limits, but not a narrow-
ing down of consciousness, (much less a “ splitting” of consciousness
or of personality as the thing unfortunately has sometimes been called).
In order, however, not to be guilty of premature judgment, I have
avoided the terms “unconscious” and “ unattended to,” and chose ex-
pressions which leave these finer distinctions untouched.

204 THE HORSE OF MR. VON OSTEN

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 character-
istics.

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 ex-
pectation 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 en-
sue. 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.

EXPLANATION OF OBSERVATIONS 205

From infancy we are trained to keep all of our volun-
tary muscles under a certain measure of control. During
the state of concentration just described, this control is
relaxed, and our whole musculature becomes the instru-
ment for the play of non-voluntary impulses. The
stronger the customary control, the stronger must the
stimuli be which can overcome it. The steady unremit-
ting 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 move-
ments as by a flow of perspiration (we have many excel-
lent examples of this given by Manouvrier) ** 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 expres-
sive movements occur, the motor pathways must be par-
ticularly 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.,

4. The power to distribute tension economically—i.e.,
the ability to sustain it long enough, and to release it at
the right moment (after the manner of the curves de-

206 THE HORSE OF MR. VON OSTEN

scribed on page 93), and to control properly the un-
avoidable variations which will occur.*

* The mental state just described is probably essentially the same as
that of the spiritualistic ‘‘ mediums” when they are occupied with table-
rapping and table-moving. In both’cases concentration is very intense,-_—
in other words, the field of attention is limited. We saw that this state
not only favors the tendency toward involuntary movement, but on ac-
count of the absorption of the individual’s attention by a certain limited
content, the person will be unaware of the voluntary movements as
they occur. And we are not necessarily here dealing with neurasthenic,
hysteric, or other diseased nervous conditions. In the case of table.
rapping there are movements of the hands, in our case there are those
of the head. Our head, balanced as it is upon the cervical vertebral
column, is continually in a state of unstable equilibrium and therefore
peculiarly susceptible to movement-impulses of everykind. But I could
induce not only movements of the head, but also of the arms and legs,
and this by having the subject assume a posture which enabled him to
hold arms or legs in as unstable a position as possible. He might
stretch out his legs horizontally before him, or he could raise them ver-
tically upward as in the hand-stand in gymnastic work. An extract
from a treatise by Count A. de Gasparin,®# which appeared about the
middle of the last century, may serve to show how close the corres-
pondence between the two processes, that of getting the table to rap
and that of causing Hans to respond, really is. The report of this
writer, based upon the detailed record of his tests in table-moving and
table-rapping, closely parallels in many minute detail the observations
which were made in the course of our experimentation with Hans. The
case is all the more remarkable when we bear in mind that this writer
did not seek the cause of the phenomena, as we did, in involuntary move-
ments, but thrusting aside this explanation, he posited the cause in the
agency of some mysterious fluid. It may not be amiss to say that this
as well as most other references were consulted after the present experi-
ments and introspections had been completed. Of the page references
preceding the following citations, the first always refers to the page in
the French original, and the other, enclosed in brackets, to the parallel
passage in the present monograph.

P. 49 [31]. Some questioners are especially suitable (‘ experimenta-
teurs hors ligne”), but in their absence, other persons may also operate
successfully (“le succés, quoique moins brillant alors, n’est pas impos-
sible.”’)

EXPLANATION OF OBSERVATIONS — 207

The experience of a number of practical men, who
have had much to do with horses and yet achieved but

P. 25 [229]. But even the most suitable questioners do not always
succeed equally well (“les plus stirs d’eux-mémes ne réussissaient pas
également tous les jours.”)

P. 42 [151]. When the questioner is in any way indisposed, the
measure of success is also less.

P. ot & 87 [150]. The Questioner must first get into the sweep of
things (‘‘en train”), and once he has done so, all interruption what-
soever must be avoided.

P. 91 [93]. Unless there is sufficient tension on the part of the ques-
tioner, the test will fail. (“La volonté est-elle absente, rien ne bouge.”)

P. 210 [93]. When there is too low a degree of tension, then too
great a number will be tapped (“si votre volonté ne les [les tables] ar-
réte pas au moment ou se termine le chiffre pensé, elles continueront
indéfiniment.”)

P. 31 [93]. But too great concentration of attention will also produce
failure (“s'il n’arrivait.... de désirer trop fortement le succés et de
m’impatienter en cas de retard, je n’avais plus aucune action sur la
table.”)

P. 36 [151]. If the proper mood (“ entrain habituel ”) is wanting and
the tests are unsuccessful, it is best not to attempt some new and diffi-
cult experiment, but to turn to some that are simpler and more enter-
taining (“La table obéissait mal; les coups étaient frappés mollement et
comme a regret. .... Alors nous avons pris un parti dont nous nous
sommes bien trouvés ; nous avons persé€veré, et persévéré gaiement;....
nous avons écarté la pensée des tentatives nouvelles, et insisté sur les
opérations aisées et amusantes. Aprés un certain temps les disposi-
tions étaient changées, la table bondissait et attendait 4 peine nos com-
mandements.”) ;

P. 199 [41, 90]. It is not necessary to enunciate the questions aloud
(“On est convenu que celui qui commanderait ne prononcerait pas a
haute voix le nombre de coups, mais se contenterait de les penser, aprés
les avoir communiqués a V’oreille de son voisin. Eh bien! la table a
obéi. Il n’y a jamais eu la moindre erreur.”)

P. 199 [64 ff.]. The large numbers are tapped more rapidly than the
small ones (“la table a indiqué notre Age tel qu'il était dans notre es-
prit, se hatant méme de la maniére la plus comique lorsque le nombre
des coups a frapper était un peu considérable.”)

P. 210 [35 ff.]. Tests in which “ procedure was without knowledge ”

208 THE HORSE OF MR. VON OSTEN

very modest success with Hans, goes to show that it is
not always the lack of sufficient authoritativeness, men-
tioned under heading 1 that is the sole cause of failure,
as has been claimed so often. That the horse was, to a
certain degree, influenced by this element of authority is
shown, however, by the following incident. A certain
gentleman, when alone in the courtyard with Hans, re-
ceived responses only so long as I (concealed in the barn)
kept the barn-door open just a little, so that my presence
could be known to the horse. As soon as I closed the
door, Hans refused to respond to the gentleman. Those
who possessed sufficient power of concentration and the
requisite motor tendency—the two characteristics men-
tioned under 1 and 2 above,—were able to obtain re-
sponses from the horse without any previous practice.
Practice merely effected a more economic distribution of
attention, so that the larger numbers especially were
more successful as a result (pages 68 and 89). Those
who were lacking in either of the characteristics men-
tioned under 2 and 3 would not be aided even by the
greatest amount of practice, as is shown by the case men-

failed completely (‘‘ Les tables ne révélent pas ce qui n’est pas dans la
pensée et dans la volonté de l’expérimentateur; quand on veut les
charger d’autre chose que d’obéir comme des membres, on arrive 4 des
erreurs continuelles.”)

P. 28, 29, 217 [72]. When of two experimenters each tries to get
the horse to tap a different number, then that one who is the better able
to compel the animal’s attention, will be the successful one. (“ L’un veut
faire prévaloire un chiffre pensé plus considérable, l’autre un chiffre
pensé moins considerable .... Eh bien: l’opérateur le plus puissant
Vemporte.” “ Ainsi A est chargé secrétement de faire frapper 25
coups, B est chargé secrétement de l’arréter 418; A l’emporte, et les
25 coups s’achévent.... On fait maintenant l’inverse : B est chargé
secrétement de faire frapper 13 coups; A est chargé secrétement de
Varréter 47; A l’emporte encore et le chiffre 7 ne peut étre dépassé.”)

EXPLANATION OF OBSERVATIONS 209

tioned in Supplement III (page 255).—That many in-
dividuals were at first successful but were later unable
to get any successful responses, is to be accounted for by
_ the fact that the power of concentration, at first present,
later rapidly disappeared. © ‘This © ‘temporary increase in
the power of doing mental work was first investigated
experimentally by Rivers and Kraepelin,®® and was called
by them “ Antrieb” and aptly likened to the first pull of
a team of horses in starting off. This, too, explains an
experience which befell a number of the horse’s visitors,
who later described it to me. Wishing to utilize a mo-
mentary absence of Mr. von Osten, they excitedly put a
hasty question to Hans, and with amazing regularity
received correct responses.—Besides Mr. von Osten, Mr.
Schillings and myself, not many were always able to in-
duce Hans to bring the colored cloths or to execute the
head movements. It was easy, on the other hand, to get
him to nod. Therefore there was some truth in Mr. von
Ostens’ assertion, that Hans would be unable to answer
a difficult question if he had not previously indicated by
means of a nod that he had grasped its import. Those
who were not concentrating sufficiently, would not look
into Hans’s face, when he was expected to nod, and
would not bend over, when Hans ought to begin tapping—
such persons could not, therefore, since they did not in-
duce Hans to nod, elicit the tapping. I, myself saw the
“no” successfully elicited only in the case of Mr. von
Osten, Mr. Schillings and Mr. Hahn; the “right” and
“left” only in the case of the former two. It must re-
main uncertain whether this failure on the part of other-
wise suitable persons to elicit the responses for “ right ”
and “left ” was due to their accompanying these ideas by
movements of the eyes instead of by movements of the

H
'

i

i

210 THE HORSE OF MR. VON OSTEN

head, (page 106). For unfortunately it was not possible
to make special tests to discover whether Hans reacted to
isolated eye movements. There is, however, more than
one reason why I would doubt this. Taken all in all,
there were but few persons who were entirely represent-
ative of the type described (c. f. page 31)—they were
those who are commonly characterized as being of a lively
temperament and strongly impulsive. Thus Hans
acquired a reputation for “ Einkennigkeit”’, that is, he

__would accustom himself only to certain persons. Such

__a reputation was hard to reconcile with his much praised
__ intelligence.

In closing, just a word on the influence of the public
that was present. As was shown on page 69, the public
in general did not influence the horse in. his reactions.
The effect upon the « tioner, however, was unmistak-
able, and worked in a twofold manner.} On the one hand
the questioner’s zeal was increased and with it the ten-
sion of concentration. @On the other hand, it introduced
an element of diversion, and attention was divided be-
tween the horse and the spectators, and thus concentra-
tion suffered. If the disturbing effect was slight, as in
the case of Mr. von Osten, then the favorable influence
exercised by the presence of the public outweighed the
unfavorable. Mr. von Osten was, for that reason, often
particularly successful when working in the presence of
a large body of spectators. This was noted by many and
was ascribed to the ambition of the horse. When, how-
ever, a person was easily diverted, as was Mr. Schillings,
then the presence of the public had a less fortunate effect.

This, then, completes my explanation of the facts
gleaned from observation and experimentation. It ac-
complishes all, I hope, that may be expected of an ex-

EXPLANATION OF OBSERVATIONS | a11

planation. All the known achievements of the horse, all
the successes and failures of the questioner, have been re-
duced to a single principle; no secondary hypothesis has
been invoked, and but slight place has been given to the
element of chance. Nevertheless, it may not be out of
place to forestall two objections which might possibly be
raised. | First, some may assert that it was through our
experimentation that the horse became mechanized and
incapacitated as regards conceptual thinking; that form-
erly he really could solve arithmetical problems, and only
later developed the very bad habit of depending upon the
signs which I gave him. This objection is to be refuted
in that I did not originate these signs, but first noted them
in Mr. von Osten, himself, and in that Hans still works
as faithfully as ever for Mr. von Osten. I have learned
from many trustworthy witnesses that the horse still con-
tinues to give brilliant exhibitions of his “ ability”. If,
on the other handY/anyone should assert that it was only
with us that Hans reacted to movements, but that with
his master he really thought and still thinks, then I must
ask for proof. This latter argument is by no means very
original. When Faraday in 1853 proved experimentally
that “table-rapping ” is the result of involuntary move-
ments on the part of the participants standing about the
table, the spiritualists asserted that his experiments had
nothing in common with their own proceedings, because
his subjects (who by the way, had been up to that time
firm believers in table-rapping) probably did move the
table, they said, while they (the spiritualists) do no such
thing.®®

CHAPTER VI
GENESIS OF THE REACTION OF THE HORSE

In the preceding discussion we have regarded the
achievements of the horse as well as Mr. von Osten’s
explanation of them, as matters of fact. Let us now con-
sider the question: How did the horse come by these
achievements, and how did its master arrive at his curi-
ous theory in explanation of them? Did he indeed seek
to instill in the horse’s mind the rudiments of human
culture through long years of painstaking instruction in
accordance with the method described in Supplement I
(page 245)? If that is the case, then, of cotirse his hoped-
for success was only seeming, not real. Or did he, as so
many critics aver, systematically train the horse to re-
spond automatically to certain cues, and propound his
theory merely for the purpose of misleading the public?
There might possibly be another alternative, viz.: was
there a mixture of instruction and of training to respond
to cues?

The production of the horse’s achievements would not
require a great deal of explanation, if it were a case of
mere training for the purpose of establishing certain re-
sponses to certain cues. It might be desirable, however,
before deciding in favor of one of these possibilities, to
indicate briefly the process of development, as it might
occur, if the point of view is taken that bona fide instruc-
tion was given.

212

REACTION OF THE HORSE 213

This development would probably be as follows :—Mr.
von Osten, as the result of theoretical speculation or of a
misinterpretation of the facts of experience, having ar-
rived at the conclusion that the horse possessed extraor-
dinary capacity, finally undertook to instruct a certain
horse for a period covering three years. This one hav-
ing died, he, nothing daunted, undertook the education of
another one. What it was that influenced this old
teacher of mathematics to deprive humankind of the bene-
fit of his extraordinary pedagogical ability and love of
teaching, we do not know. It may be that he had had
bitter experience in that line, or again, mayhap the new-
ness and tremendousness of this other task stimulated
him. His first problem must have been to arouse the in-
terest of the animal in this process of education. It was
hardly to be believed that Hans would eagerly codperate
in a process which promised to yield him no immediate
benefit. The teacher sought to overcome this lack of im-
mediate interest by the means of rewards. To Hans the
sweet carrot was as toothsome a bite as candy is to the
child. And since the horse was furthermore kept on low
rations on account of the relatively low amount of physi-
cal exercise he took, the anticipation of the carrots was
doubly enticing.

The first thing that Mr. von Osten sought to teach the
horse, according to his own statement, was the significarice |
of fie names of colors and of the spatial directions such
as “up”, “down”, etc. In the case of children there
is a simple test by means of which we may discover if
they have put any content into these words. The test is:
‘Do they, themselves, use them correctly? Do they call
the blue, blue, and the red, red? Since the horse could
not speak, his instructor had to give him some means by

\
|

214 THE HORSE OF MR. VON OSTEN

which he could make himself understood. He taught
Hans to approach the colors and select the cloth of the
color wanted. He also taught him to make those move-
ments of the head or body which correspond with the
expressions: “up”, “down”, etc.

First of all, Fans had to be taught to bring the cloths.
Then began the pointing out of the different colors, ac-
companied each time by their proper names. It is very
probable that at first Hans had to be led each time to each
separate colored cloth and taught to raise it or to touch
it with his nose. Later, Mr. von Osten, after having pro-
nounced the name of the color, remained at his place,
with his head and body directed to the cloth in question
and gazing intently at it, in order to see whether or not
the horse was pointing out the right one. Naturally
Hans would, at first, fail a hundred times-where he would
succeed but once, but since the horse would receive the
anticipated reward in case of success, he gradually be-
came conscious that this reward was attached to execu-
tions which had some special mark. This special mark
would be expressed in human speech by the statement
that the horse would go in the direction indicated by the
position of the instructor’s body. For Hans, of course,
this would not take the form of an abstract statement,
but simply of a definite way of seeing and of going and a
cofrelation of the two in a certain definite manner,—the
whole being a process, the elements of which remained
unanalyzed and unaccounted for by Hans. Owing to the
position of the eye, it was possible for him to keep his
master within his field of vision, while he was approach-
ing the cloths. And only when he had correlated his ap-
proach in a certain definite manner with his visual per-
ception of the master, i. e., only when he had felt his way,

REACTION OF THE HORSE 215

as it were, along the latter’s line of vision, did he receive
his reward. A sufficient number of repetitions was all
that was necessary to establish an 2 association in the
‘psychological sense of the term. In the same manner,
dogs will learn, as was indicated on page 177, to bring an
object upon which the master has fixed his gaze, it mat-
tering little whether or not the name of the object be
enunciated. There is only this difference, that, in the
case of the dog it is not possible to keep the image of the
master within the field of vision; but neither is it neces-
sary, for he has récognized—the- object before he has
started for it. We must remember, however, that it does
not simplify an attempt at explanation to assume that Mr.
von Osten consciously trained the animal to respond to
certain bodily positions of the questioner. For, even in

this case, it would be necessary to explain how it was pos- |
sible for him to train the horse to heed the cues.—In the.’

course of time, the instructor may have noticed that when-
ever he moved during the course of a test the horse in-
variably failed. But he may have regarded this merely as
an incidental distraction and afterward was careful to re-
main quiet. As soon as he increased the number of cloths
upon the floor, it was no longer possible for him to give
the horse such accurate directive signs, and the number
of errors consequently increased. Ascribing them to the
inattentiveness of his pupil, he sought to encourage him
by such calls as “look out”, “ look there”, “see there”,
believing that, thus, he was Aieectires the haved attention
to the desired color. Without understanding the mean-
ing of the calls, Hans learned, however, to keep moving
just as long as the calling continued, for if he did this he
was regularly rewarded. An association was established
between the call and the impulse to move on. And with

216 THE HORSE OF MR. VON OSTEN

these two associations established, Hans gave the impres-
sion of having grasped the meaning of the color terms.

The origin of the proper movements in response to the
terms “up” and “down” may be explained by the fact
that the movements themselves were practised in a
purely external fashion. Thus, whenever the word
“left”? was pronounced, the horse’s head was pulled to
the left by means of the bridle or the reward was held off
to that side. Later, Mr. von Osten, who looked expect-
pectantly at the horse’s head, whenever he pronounced the
word would unconsciously move his own head in the di-
rection in which he desired the horse to turn. This is
quite in accord with the words of Darwin to the effect that
whenever we wish an object to move in a certain direc-
tion it is well-nigh impossible for us to inhibit an uncon-
scious, involuntary movement in that direction. Proof for
-this-may~ be found ‘on all sides, in daily experience.®”
Imagine, for instance, the strain sensations of the bowler
or billiard player as he follows the moving ball. It is im-
possible to decide whether Mr. von Osten, consciously
continued to image the head movements which he ex-
pected the horse to make or whether these anticipatory
images later remained below the threshold as was always
the case with Mr. Schillings and myself (see page 100).
But this question is of little significance, for even assum-
ing that he always thought of the movement he expected
on the part of the horse, this by no means implies that he
was conscious of the movements on his part, which were
associated with the thought process.

Everything up to this point might be explained as the
working of simple ‘memory association, but when we
come to problems in counting and arithmetical calcula-
tion, we are in the field of conceptual thought. Here,

REACTION OF THE HORSE 217

again, it was necessary for Mr. von Osten to invent a
suitable means of expression for the horse, and once more
this had to be borrowed from the treasury of gesture-
language. Tapping with the hoof was naturally hit upon
as one of the normal, expressive movements of the horse.
This has long been used by trainers, in preparing horses
for show purposes. The method used in training the
horse to make this response is of no import, whether it
was by touching his foot with the hand, or tapping his
leg, or by any other means.

It is possible that many will declare, as being non-
sensical, any attempt to introduce number-concepts * into
an animal’s mind, because the necessary motor basis is
lacking. We will not, just at this point, stop to discuss
whether or not it was not possible to develop number-
concepts from purely auditory or visual representations.
It is evident, however, that Mr. von Osten believed that
a motor basis of some sort was essential. In the case of
man this basis is found in the enunciation of the number
names (or in the manipulation of the fingers). Mr. von
Osten seemed to think that he was justified in assuming

that, even in the case of the horse, some form of inner
“articulation of the word-sounds was possible ;—at the
same time, in so doing, he did not blink at the psycho-
logical difficulty of this hypothesis. The tapping of the
foot was to be regarded merely as the expression of the
process of inner counting, but not as the motor basis of
the process. For this latter purpose tapping would be
quite inadequate, for the number complexes which arise
in the summation process of counting, could not be dif-

* The author intends to take up the problem of counting, so-called, on
the part of animals and of the principle involved, in another work soon
to be forthcoming.

218 THE HORSE OF MR. VON OSTEN

ferentiated by mere tapping with the foot, any more than
a child could learn to count by employing only one finger.
Mr. von Osten evidently imagined the process was some-
what like this: Whenever Hans was about to count 5, he
would enunciate inwardly the numbers from 1 to 5, and
would accompany each word with a tap of the foot.
Since, furthermore, wooden pins and balls could be used—
as in the case of children—for giving visual content in
learning the significance of the number-terms, it seemed
as if all the conditions necessary for the formation of
number-concepts were supplied. However, the most es-
sential thing had to be presupposed, viz.: that the horse
virtually possessed the general power of forming con-
cepts,* and that all that had been lacking was the suitable
conditions for its development. Mr. von Osten held
~ tenaciously to this conviction, and it was this conviction
that was the basis for the infinite patience with which the
tests had been pursued.

To come now to the learning process itself ;—we may
assume that, at first, whenever the horse began to tap in
response to commands, he would receive a reward for this
purely mechanical feat. Wooden pins were then planted
on the ground and designated as: one, one two, etc., and

* There are some who believe they are warranted in concluding the
opposite from the structure of the animal’s brain alone. We may say
that the brain of the horse, compared with that of the ape, or even that
of the dog, represents a relatively low type of development. But owing
to the rapid changes in the views, often contradictory, concerning the
nature of the nervous structures and processes underlying the thought
process, any conclusion based on such views would be premature. For
this reason we cannot agree with the French physiologist who was
dissecting the brain of a horse and, struck by its smallness of size, ex-
claimed: “ When I saw your proud look and beautiful neck, I hesitated
a moment before mounting upon your back. But now that I have seen
how small is your brain, I no longer have any qualm about using you.” **

REACTION OF THE HORSE 219

each time someone would raise the horse’s foot as many
times as the count demanded (see Supplement I). Then
Mr. von Osten would take his stand at the horse’s side
and would command him, let us say, to tap 3. Hans
noting merely (from his master’s position) that he was |
expected to tap, would begin. The instructor, who had —
bent forward in order to watch the horse tapping,* would |
involuntarily straighten up again at the third tap, without —
being conscious of it and quite unaware that he was thus
giving a signal. The horse would be startled, and some- |
times he would immediately cease tapping and sometinies |
not. But it was only in the first case that he would re-
ceive a reward. Thus, unknown to the instructor, an
association became established between the sight of the
upward jerk of the instructor and the act of ceasing to
tap. To be sure, the animal would receive sundry visual ~
impressions from the wooden pins set up before him and
the auditory stimulations of the spoken number names, on
the basis of which, the concepts were to be formed in his
mind. But in this chaos of visual impressions (at times
there were two wooden pins, then three, then four, some-
times there were the pins, at others, the balls of the count-
ing-machine)—and in the babel of word-sounds—which
evidently meant nothing but noise to him—amidst all this
there was but one constant element: the final movement
of the instructor’s body. The moment the horse reacted
to this, he would receive the tidbit at the hands of his
overjoyed master, and thus he became more and more ac-
customed to attend to this jerk, even after it had grad-

* This natural and close connection between the process of attention
and the movement toward the object attended to is clearly expressed in
our English and French terms, derived from the Latin “ tendere ad—,”
to reach toward—.

220 THE HORSE OF MR. VON OSTEN

ually decreased in scope. And the reason again, why this
jerk tended to become less pronounced was that the tests
were gradually becoming more and more successful. For,
corresponding to the degree in which the horse began to
react properly, the instructor’s tenseness and excitement
tended to decrease, and with this decrease of the emo-
tional element in the man’s consciousness, the accompany-
ing non-voluntary, expressive movement gradually be-
came less pronounced until it attained that extraordinary
refinement which it possesses to-day. We noticed also,
that whenever the horse, for any reason, had to be trained
anew, Mr. von Osten’s movements would, on the whole,
become somewhat more gross, as for instance after the
tests with the blinders. There is not a shadow of a
doubt that this increase in the movement’s extent was en-
tirely unintentional, since the horse could not see his mas-
ter at all on account of the blinders which had been
attached to the trappings.

In the same way it is possible to explain the details.
Mr. von Osten himself said that at first Hans had tapped
at times with his left foot, at times with his right, just
as he pleased. But later his master taught him to tap
only with the right. Whenever he began with the left,
Mr. von Osten would immediately interrupt him, and he
was allowed to add only a final tap with his left foot.
Thus, this additional tap which was sometimes made with
the left foot was but the vestige of an earlier rudimentary
habit. The signal for it was the stooping posture in which
the master remained after the head-jerk had been made.
Whenever Mr. von Osten had given Hans a small number
to tap, he would bend forward only a little. But when
he expected a larger number he would bend forward
somewhat more, owing to the desire to observe the tap-

REACTION OF THE HORSE 221

ping more carefully. From the slight inclination of the
master’s body the horse would get the cue that he was ex-
pected to tap for a short time only, by the greater de-
gree of inclination he would know that he was to tap for
a longer period. In the second case he tapped rapidly
and did not raise his foot as high from the ground—
evincing a regard for the saving of energy, which may
well be attributed to a horse. And thus arose the con-
nection between the degree of inclination of the in-
structor’s body and the horse’s rate of tapping.

So, now that the ability to count and solve problems
had become fixed—as the old gentleman thought—he be-
gan to instruct the horse in other branches. Since every-
thing had been translated into terms “which were to be
expressed by means of tapping with the foot, and thus
really put into terms of number—which was perhaps
natural for an old teacher of mathematics—the same
mechanism was involved in these accomplishments as in
those of counting, etc. Mr. von Osten saw the animal’s
intelligence steadily increase, without having the slightest
notion that between his words and the responsive move-
ments of the horse, there were interpolated his own un-
conscious movements—and that thus instead of the much
desired intellectual feats on the part of the horse, there
was merely a motor reaction to a purely sensory stimulus.
It has been a common custom of man to posit some ex-
traneous cause for movements resulting from certain in-
voluntary motions of his own, of which he is not aware,
(witness the divining-rod).* And furthermore, when

* G, Franzius, privy counselor of the admiralty, master of the dry-
dock at Kiel, is responsible for the undeserved revival of the ancient
belief, long buried by science, that the divining branch is put into motion
solely as the result of the influence of hidden springs or treasures, and

222 THE HORSE OF MR. VON OSTEN

these results appear to be rational, the tendency is to
seek their cause in some extraneous intelligence, not his
own. Just as the spiritualists ascribe the “ messages ”
which are revealed to them through table-rapping, to cere
“tain rational spirits, so Mr. von Osten credited the intelli-
gence of the horse with the result produced by his own |
involuntary signs—i. e., with the proper solution of prot
lems.

Two other phenomena may have tended to strengthen

Mr. von Osten’s belief in Hans’s intelligence] 'One was
the misleading similarity with which the horse’s supposed

without any agency in the person who is holding it. The untenability of
this theory comes home to us most forcibly when we recall how various
are the kinds of things which have heen discovered by means of the
branch. First there is gold and water, which are the only ones men-
tioned by Mr. Franzius. The water can be thus discovered only when
it flows below ground, say that which is passing through the mains of a
city, whereas the water of the Rhine or the Elbe would have no effect
on the branch. Besides gold, every other kind of metal has been sup-
posedly located by the branch,—as well as coal, gypsum, ochre, red-chalk
sulphur and petroleum,—according to the desire of the one searching.
Thus, the very same branch that justa moment ago was influenced by
the least bit of underground water, may remain unaffected by the presence
of a large body of water, if in the meantime I have changed my plan
and decide to search for coal or for gold. But that is not all. The
branch will point out a murderer or the place where a murder has bcen
committed, it will discover the thief or his trail, as well as the things
stolen or merely touched by him. It will indicate where the boundary-
stone that has been moved, ought to stand. The branch further dis-
closes the sins of the persons concerning whom it is consulted, as well
as their talents and abilities, the journeys they have made and the wounds
they have received. It will indicate whether or not a person has money
and how much. It can announce what absent persons are doing and
what apparel they are wearing, and of what color it is. It will give in-
formation on theological, medical, zoological, and botanical questions.
In fine, no matter what the question, it will never fail of an answer.!™, 1°

The impossibility of explaining the phenomena in a purely physical
way was recognized at a very early date. For a long time the activity

REACTION OF THE HORSE 223

errors in computation and the poorly adjusted concentra-
tion of the questioner, were expressed. We recall the
difficulty in the case of very high numbers. This might
easily be considered as being due to the horse’s ability to
work more readily with small, rather than with large
numbers, whereas, as a matter of fact, it was due solely
to the difficulty of the questioner to keep his attention
concentrated upon the number for so long a time. We
recall also the frequency of errors of one unit too few
and one unit too many. These were easily interpreted as
miscounts on the part of Hans, but in truth were the re-

of the users of the divining rod seems to have been restricted to the
search for metals. ‘The first (or one of the first) to raise his voice
against it was the learned G, Agricola 1 (1556), and after him there
were many who all wrote more or less independently of one another.
Aside from swindle and chance, it was usually believed that sorcery of
the agency of Beelzebub was involved, and for that reason the Church
has repeatedly forbidden the use of the divining-rod. But even in the
17th century we find some who believed that it was imagination alone
that moved the person’s hand, and with it the rod, 108, 104 (« fortassis
etiam phantasia manum in motum concitante”’); and that points out
the essentials of the solution of the phenomenon, and we will not go
into the matter here in detail. A number of complex psychological
problems arising in connection with it are still waiting to be solved, but
this much appears certain; the staff or branch plays no other part in the
whole process than that which is served by the three levers in the tests
described in Chapter IV (pages 116 ff.),—they simply magnify the ex-
pressive movements of the diviner. And so we can understand why
the instruments serving as rod might be so varied. Hay-forks, pickets,
clock-springs and pendulums, scissors and pliers have been used. A
knife and fork or two pipes, fastened together, an open book, and even
asausage, grasped at both ends and thus bent together somewhat,—
all have scrved the purpose equally well. Wecan understand, too, how
some adepts are able to achieve the same degree of success—-for they
do succeed beyond a doubt—without any rod whatever, but simply by
placing the index fingers end to end and bending them somewhat, and
even by merely groping about with hands outstretched or folded before
them,1%6

224 THE HORSE OF MR. VON OSTEN

sult of the poorly concentrated attention of the questioner.
2 Added to this was the seeming independence and self-
sufficiency of the horse. Often the number given by him
was other than that desired by his master. Usually Hans
was in the wrong in such cases, but sometimes, too, he
was tight. At any rate, this served to give the impression
of independence of thought which his master so thor-
oughly believed he possessed, and which was the goal
of his endeavors—though as a matter of fact he was
farther removed than ever from that goal.

Some may ask: Does not this whole process partake of
the essentials of all training, (though cumbersome and
misunderstood, to be sure), and is there any need of in-
vestigating whether or not the actual development was
of the sort here outlined, or whether it actually took the
course common to all training?

In order to answer this question we must determine
more specifically what we mean by the term “ training”.
Usually we take it to mean the establishment in the ani-
mal, of definite habits of motor reaction in response to
certain stimuli purposely selected by the trainer, and with-
out involving any process of animal consciousness other

~than association. ; Such a conception may be applied also
to man, if we assume that the higher thought processes
can be eliminated. If that were the case, the above defini-
tion would not have to be changed, not even with regard
to the word “animal ”, for we must take it in the antique
sense of “zoon”, a signification readopted by modern
zoology. The concept may be widened, however, by
omitting the differentia of “ purpose”, or even more, by
including the habitual association of ideas or images
(instead of movements) with certain sensory stimuli,
But in so doing, we must bear in mind that we are going

REACTION OF THE HORSE 225

beyond the usual content which in everyday practice is
put into the term “training”. Especially, when we cease
to regard the presence of purpose in the trainer’s mind
(both in giving the stimulus as well as in the habituation
of the animal to them) as essential. When this is done,
the conception of training really resolves itself into the
much wider conception of habit-building, and the whole
discussion becomes merely a quarrel over words. In
order to obviate this, let us bear in mind that in the fol-
lowing, the word “training” is always taken in the usual
and narrower sense. The term then is still ambiguous
only in so far as it has not merely its original significance
of the act of purposely habituating (a person or an ani-
.mal) to perform certain definite movements, but by trans-
ference is also used to denote the effect, i. e., the occur-
"rence of the movements in question. But this does not
really detract from the clearness of the concept itself.
Having cleared up the question of definition, let us re-
turn to our original problem: Does the hypothetical ac- ;
count of the probable development of the horse’s reac- |
tions, which is given on pages 213 to 220, represent a
case of training? This must be denied decidedly with |
regard to the tapping of numbers and the solution of/
arithmetical problems. For here the sensory stimuli which’
were purposely given, i. e., the wooden pins. the balls,
and the spoken words, were intended to subserve the
function of arousing not movement, but thought proc-
esses in the horse; whereas the function of the horse’s
movements was to give expression to these thought _
processes. Of the really effective stimuli—the slight ©
movements on his part—the master was never conscious,
much less were they purposely made. The same holds
true for the “up” and “down”, “yes” and “no”, etc.,

226 THE HORSE OF MR. VON OSTEN

for here also Mr. von Osten counted upon the rise of the
corresponding concepts, and not merely upon a purely ex-
ternal, mechanical association of meaningless sounds with
certain movement-responses on the part of the horse.
This might also explain the genesis of Mr. von Osten’s
belief that Hans was able mentally to put himself in the
place of the questioner, (page 19). At any rate it is
very improbable that he, Mr. von Osten himself, clearly
distinguished between the concept: “up” and the sound
of the word “up”. When we come to consider the
horse’s selection of the colored cloths, and even more his
leaping and rearing, we find that the distinction between
“training” and “instruction” vanishes. If we had to
deal only with this class of achievements, we might per-
haps say, without fear of going very far wrong, that the
only difference between this and the ordinary form of
training was that Mr. von Osten had intended to train
the horse to respond to auditory signs (words), but had
unintentionally trained him to respond to visual signs in-
stead. But it is not this type of performance that has be-
‘come the bone of contention. Just as it would be mislead-
ing to maintain that Mr. von Osten’s effort was nothing
other than a case of training, so it also would be unjustifi-
able to designate the results of his effort by that name,
since the really effective stimuli were not, as has been
pointed out just now, given intentionally.

As far as the horse is concerned, it is a matter of in-
difference whether or not really effective stimuli were
given intentionally by the questioner. The animal knows
nothing of human purposes and if he were transferred to
a circus, he would find nothing new in the method em-
ployed there, except the use of the whip. We, however,
define our concepts from the human and not from the

REACTION OF THE HORSE 227

horse’s point of view. We may definitely say, therefore,
that the method described cannot be regarded as that of
training, neither in its application nor in the effect pro-
duced, though in the latter it closely simulates the effects
of the training method.

Having thus differentiated between the methods of in-
struction and training, let us now attempt to decide on
the basis of such indications as we may possess, which of
the two was actually represented by the development of
the horse’s attainments. Surveying the facts which we
have at hand, we may say that there are hosts of reasons
Everything that we know from our own observation atid
from the well-attested statements of others, with regard
to the actual process of instruction, weighs against the
assumption. ‘Another evidence of this is the long period
of time which Mr. von Osten required (both in the case
of Hans, as well as with his predecessor), whereas the
same end would have been much.more speedily attained
if it had been a case of training. Ss further argument is
the fact that a large horse was selected for the purpose,
whereas a small mare would have been far more suit-
able, (c. f., ‘‘ Clever Rosa”, page 7).-“Again, the whip.
that sorcerer’s rod of all professional ‘trainers, was here
absent. And finally, many traits of character of Mr. von
Osten, a well as his conduct during the whole course of
events, militate against such an assumption. He gener-
ously turned the horse over to us, as he had given-it over
to Count zu Castell, Count Matuschka and Mr. Schillings.
He eagerly besought a scientific investigation. He had
made several reports to different ministries. All of these
acts could only hasten the denouément. What could have
been his motive? Some thought they detected an effort

228 THE HORSE OF MR. VON OSTEN

at pecuniary speculation, and an advertisement of June,
1902, in the “ Militarwochenblatt””, in which Hans was
offered for sale, seemed to confirm the conjecture. Mr.
von Osten says that this occurred at a time when he him-
self was sick and had become tired of the job. And why
should he not be willing to sell even a thinking horse,
since he had become convinced that any other could be
instructed in the same way? Besides, I have it on good
authority that after the publication of the September re-
port he received several exorbitant offers; to mention
only one of them: a local vaudeville company was ready
to pay him 30,000 to 60,000 marks per month. He re-
fused every one of these offers. Some may say that per-
haps he wanted still more. But if he knew that the day of
judgment was close at hand, he also knew that before
then, if ever, was the sunshiny day on which to make his
hay. A more auspicious time he could never hope to see
again.—Let us add, once more, that he never charged
admission to any of Hans’s performances, although there
were many who were anxious to see the horse, and many
enthusiasts had come from a great distance. And finally,
he was an old man, unmarried and entirely alone, a prop-
erty owner, but a man whose wants were few and very
simple—and his Hans was almost his sole companion.
Is it possible that such a man, one who had all the pride
of gentle birth, would become a trickster in his old age,
all for the love of money?

The unreliability of Mr. von Osten’s signs is good
proof of their involuntary nature. Anyone who had seen
him work with the horse could not have helped noticing
that he certainly did not have complete control over the
animal, and was not able, at a given moment, to make
Hans perform a certain feat, as would have been the case

REACTION OF THE HORSE 229

if the process had been one of “training”. Again and
again Hans failed to make the right count. Before a
large audience, one time, it took four tests to get him to
tap properly up to 20, and in all four I could note clearly
that it was Mr. von Osten who, by his involuntary pre-
mature movements, was the innocent cause of the failure.
On another occasion, after Hans had done some beauti-
ful work in fractions, in the presence of a large number
of spectators, the master asked him the simple question:
“Where is the numerator in a fraction? "The answer
was first: “to the left”, and then, after a severe repri-
mand: “down” (below), and finally: “up” (above).
He often made just such incorrect movements of the head.
In the color-selecting tests the average of error was quite
unpredictable. With an equal number of tests, on one
day, half would be successful, on another, four fifths, on
a third, one-tenth. Often Hans appeared to be “ indis-
posed” for days at a time. The color tests would often
end in expressions of rage on the part of Mr. von Osten
and in consequence Hans would become startled and
would then storm about the courtyard so that it was dan-
gerous to try to approach him. Some may object that all
this was mere comedy and that possibly Mr. von Osten

prevented some of the tests from turning out successfully. _

But this objection is to be met by the statement that very
often failure would occur just when it was particularly
desirable to have the tests appear in a favorable light
before a large and enthusiastic assemblage of visitors.
After such failures he would be downcast on account of
Hans’s contrariness. It is also significant that Mr. von
Osten’s percentage of error, corresponds very closely
with my percentage of error in the “non-voluntary”
tests, (page 84f.), whereas he never was able to obtain

230 THE HORSE OF MR. VON OSTEN

the errorless results which I obtained in my “ voluntary ”
experiments.

But we must be careful not to confuse non-voluntary
movement and lack of knowledge of the movement. And
again we must distinguish between knowledge of the
grosser and the finer signals. Mr. von Osten was aware
of the grosser movements, and talked quite freely con-
cerning them, but in so doing, showed that he was quite
unaware of their true function. He undertook to show
us what we already knew—that, when he remained stand-
ing perfectly erect, he could elicit no sort of response
from Hans. Furthermore, that whenever he continued to
bend forward, Hans would always respond incorrectly
and with very high numbers. He knew, also, that Hans
was distracted in his operations every time the questioner
resumed the erect posture while the tapping was in prog-
ress. This he demonstrated to us on one occasion in the
following manner. He said to Hans: “ You are to count
to 7; I will stand erect at 5”. He repeated the test five
times, and each time Hans stopped tapping when the mas-
ter raised his body. Several such tests resulted in the
same way. Mr. von Osten, however, believed this to be a
caprice of the horse and at first declared that he would
yet be able to eliminate it, but later became resigned to it
as an irremediable evil. Mr. von Osten was also aware
that the questioner ought not move while the horse was
approaching a colored cloth, and cautioned me in regard
to it, though I had already noted as much. And finally, he
also knew what influence his calls had while the horse
was selecting the cloth, and he told me that it was of great
assistance to Hans to be admonished frequently, since
thus his attention was brought to bear upon the proper
cloth. Yet, when we requested Mr. von Osten to desist

REACTION OF THE HORSE 231

calling, since he was thereby influencing the horse in the
choice of the cloth, he answered: “ Why that’s just what
I wish to do!”— But though the statement that he was
aware of the nature of these grosser signs is thus seen
to be true, it by no means necessarily implies that he had
purposely trained the animal to respond to them. In
these observations of his he had builded better than he
knew—he evidently had no notion of their scientific sig-
nificance. But the same thing might happen to those
who were suppossed to be somewhat less naive, as is
shown by the experience of Mr. Schillings, who quite un-
consciously, for many months had been giving not only
the finer, but also the grosser signs, and never guessed
the true nature of affairs until I explained it to him. Nor
was it an easy matter for me to get at the facts involved
in the process, although it now all appears so very simple.
On the other hand, it is also true that Mr. von Osten -
knew nothing whatever of the finer, more minute signals,
such as the final jerk, the head-movement upward, down-
ward, etc., and it is difficult to conceive how he might
have gained any knowledge of them. We might per-
haps conceive of four possible sources. He might have~
come upon them by chance. But it is extremely im-
probable that in the million of possible forms of sig-
naling he should have hit upon those that at the
same time represent the natural expressive movements.
2 Or he might have derived a knowledge of them through
a study of the pertinent literature. I have searched
diligently for such a source, in both the old and the
modern literature, but in vain. From the sixteenth
century on, there is a series of accounts of horses that
were able to spell and to solve problems in arithmetic,
and the reports on learned dogs go back even to the time

232 THE HORSE OF MR. VON OSTEN

of Justinian, in the middle of the sixth century.’ All
of these animals were kept for purpose of speculation and
were exhibited for pecuniary reasons only. Nor does one
read that any person could work with these animals off-
hand, which was the characteristic feature of the Osten
horse.* In many cases we find mention made of the

* There is only one, and I believe it is only a seeming exception
to be found in the literature on the subject. We are told that
about the year 1840 a French revenue official named Léonard had two
hunting dogs that, besides other things, were able to play at dominoes,
and this not only with their master, but with anyone and without the
master’s assistance. The owner had educated them simply for the fun
of it, and not for pecuniary gain. This statement is made by both
writers who, apparently independently of one another, have discussed
the case, Youatt and de Tarade.! De Tarade himself played
with them, and gives directions how to teach dogs to play the game.
But his exposition is so naive, and even ridiculous, for those who know
anything about the subject, that we do not believe it necessary to at-
tempt a detailed refutation. Youatt never saw the animals. But he
tells us that not only the dog’s partner, but also the master, sat at the
game. Youatt’s assertion, however, that “not the slightest intimation
could have been given by Mr. Leonard to the dog,” but that the animal
carried on the game by means of its own observation and calculation,
appears to me a rather bold statement. After my own experience with
dogs, I firmly believe this to have been impossible. Hachet-Souplet,!
who shares my conviction, explains the matter as follows: the dog
would simply place a domino having the number of eyes named by his
partner, thus the 6 adjacent to the 6, the 3 to the 3, etc. But even so
a great deal would have to be attributed to the dog, (although in that
case real counting would by no means be absolutely necessary, for an
association between the number term and the total picture of the cor-
responding group of eyes would suffice.) But we must note that neither
of the writers mentions that the numbers were always called aloud by
the partner. After the failure of the experiments of Sir John Lub-
bock,!! we must doubt very much if a dog is able to match one domino
with another having the same number of eyes. We are therefore in-
clined to believe that this dog continually received signs from its master.
These signs probably were visual, perhaps also auditory, and they were
by no means involuntary. For in a book on the training of animals,

REACTION OF THE HORSE 233

signs to which the animals reacted. Thus for the begin-
ning or stopping of the animal’s scraping or tapping, the
signals were respectively raising and lowering of the eyes
on the part of the trainer,'® lowering and raising of the
whip "* or of the arm, stepping forward and_back-
ward,""* and as a closing signal a slight bending for-
ward.*° The signals for beginning and ceasing to bark
in the case of dogs, were the trainer’s commands to
“speak”, and, at the same time, his looking at the dog,
and then looking away for a closing sign ;1!7 or a mouth-
movement on the part of the trainer and then a withdraw-
ing of the left hand which had been resting on the hip.
Among the signals for nodding and shaking the head we
find the following mentioned: raising and lowering the
hand or arm 1° or the whip; 12° a movement of the hand
toward the horse’s nose, as a signal for nodding, and an
arm-movement as a signal for shaking the head.24 For
this last, we find recommended also a slight breathing
upon the animal,!?? and—in the case of dogs—a mouth-
movement simulating blowing, or a turn of the fingers.???
(We will not dwell upon the many signals for selecting
objects, which are mentioned, since we have already dis-
cussed this point on page 230f). In all these instances it
is plain that we have to do with purely voluntary and

which Léonard, the owner of the dogs, has published, and in which he
describes minutely the method by which they had been trained in their
various accomplishments, he does not mention with so much asa syl-
lable the game of dominoes, a thing which he certainly would have
dwelt upon, if he had believed in the animals’ power of independent
thought. He would not have remained silent concerning this greatest
—though only apparent—achievement of his educational endeavors.
But his whole book is evidence that he was too wise to have thus de-
ceived himself, and our only alternative is to believe that he was play-
ing a joke on his credulous admirers.

234 THE HORSE OF MR. VON OSTEN

“ artificial ” signals. The only example of involuntary
signs which. Mr. von Osten could have found in literature,
was that of Huggins’s dog, which need not be considered
here, since, as was said on page 177, the really effective
signs in that case were not discovered, third means by
which Mr. von Osten might have gained a knowledge of
the involuntary, natural expressive signs, would have
been by observing others. If he had had opportunity of
observing another von Osten and another Hans, he might
have gotten at the secret. But since this was not the
case, this possibility vanishes‘+A fourth possibility is
self-observation. We would then have to assume that
Mr. von Osten at first really tried to educate the horse
to think, but soon recognized the fruitlessness of such an
attempt. At the same time, he then would have noticed
his own involuntary movements and their effect upon the
horse, and having noted them, voluntarily reduced their
extent and utilized them in the training process. But
here also there is much that militates against this assump-
tion when we consider how great is the difficulty of con-
sciously refining movements which at first were rather
coarse, unless it be by the adjustment of the proper de-
gree of concentration of attention, a subtlety of method
of which we could hardly believed Mr. von Osten capable.
We must remember, also, that in the first publication re-
garding Hans which, by the way, marks the beginning
of his career, (“Das lesende und rechnende Pferd,” by
Major-General E. Zobel, in the “ Weltspiegel ” of July 7,
1904), we may read the following: “ He (Mr. von Osten)
is always willing to have the horse undergo an examina-
tion on the part of a stranger, and promises that after
Hans has become fairly well acquainted he will display
the same degree of efficiency as he displays with the mas-

REACTION OF THE HORSE 235

ter, himself. This occurred at a time when Mr. Schil-
lings, the man who was destined to prove the truth of
the statement, had not yet appeared on the scene. How
was Mr. von Osten to know beforehand that every ques-
tioner, who might appear, would execute the same move-
ments that he himself had used?. We would recall also
that not one in the great multitude of persons who worked
successfully with the horse in the absence of Mr. von
Osten, had noticed, even in the slightest measure, any of
these movements in themselves. The position and repute
of these persons vouches for their veracity—among them
were the writer of the article just mentioned, the Count
zu Castell, Count Matuschka, Count von Eickstedt-
Peterswaldt, General K6ring, Dr. Sander, Mr. H. Suer-
mondt and Mr. H. von Tepper-Laski. Some of these
gentlemen were quite unwilling to believe that they exe-
cuted such movements. This happened in the case of Mr.
von Tepper-Laski, who had visited Hans ten times and
who had, during the course of these visits, frequently
worked alone with the horse and had received correct re-
sponses. Count Eickstedt, too, although he was one of
those who had been made acquainted with the nature of
the movements involved before being allowed to visit the
horse, was unable to note them either in his observation
of Mr. von Osten, or of himself, when, in compliance with
his own wish, he was left alone with Hans. Nor did any
of the laboratory subjects, some of whom were well trained
in introspection, discover the true nature of affairs.
They were thoroughly astonished when the facts of the
case were explained to them. And I, also, as was men-
tioned on page 100, did not become aware of my own
movements, until I had noted those of Mr. von Osten.
In fine, everything would indicate that we have here not

236 THE HORSE OF MR. VON OSTEN

an intention to deceive the public, but a case of pure self-
deception.*
This self-deception is easily understood when we con-
sider the two predominent characteristics of the man: the
| pedantry of the pedagogue, and his proneness to be pos-
“sessed by a single idea, which is a peculiarity of those of
an inventive turn of mind. Adhering closely to a pre-
formed plan, he carefully and narrowly circumscribed
the scope and order of instruction. He would not go on
to the number 5 if he were not thoroughly convinced that
the 4 had been completely mastered, nor would he go on
to a more difficult problem in multiplication, until he felt
certain that Hans was entirely proficient in the problems
of the simpler sort. If he had ever put a question to
Hans before its regular order, he would have discovered,
to his amazement, that there really existed no difficulties
for Hans, and also that the horse really required no ap-
preciable time to acquire new material. Mr. von Osten
would have had a like experience if he had asked Hans
concerning the value of Chinese coins or the logarithm
of 1000. However, he never did anything of the kind,
but always adhered closely to his plan. He required the
questioner to say: “2 and 2”, and never “2 plus 2”.
Nor were capitals or Latin script to be used in the writ-
ten material. And if upon request he did so, he did it,
without faith in the result, and hence there was failure.

* P. Wasmann, S. J. in the third edition of his book, “ Instinkt und
Intelligenz im Tierreich ” (Freiburg, Herder, 1905), discusses the case
of Hans and quotes from a letter I wrote him concerning the matter.
In the quotation an error has crept in, which I would here correct.
The statement is ascribed to me that “ Hans differs from other horses
only in his extraordinary power of observation, an unintentional by-
product of intentional training,” whereas in my letter I said: “ uninten-
tional by-product of intentional education.”

REACTION OF THE HORSE 237

And so he declared that “if you use Latin script Hans
becomes confused and will be out of sorts for several
weeks thereafter.” Mr. von Osten is, and ever will re-
main, the schoolmaster, and will never become the psy-
chologist, the “ soul-vivisectionist ”._ Who would work a
child with such puzzling questions? and Hans was to him
like a child. Thus the old man believed himself to be a
witness of a continuous, organic development of the
animal soul—a development which in reality had no other
existence than in his own imagination.

Added to this pedantry was an extraordinary un-
critical attitude of mind, induced by his obsession by one
favorite idea, which blinded him to all objections. He met
objectionable observations on the part of others in one of
two ways. One method was by attributing to Hans certain
remarkable qualities, such as an extraordinary keenness of
hearing and a wonderful power of memory, or again, cer-
tain defects, such as moodiness and stubbornness,—which
as a matter of fact, were only so many back-doors by
which he might escape from the necessity of offering ade-
quate explanations. When Hans was able to give off-hand
a gentleman’s name which he had heard years before, it
was called a case of extraordinary memory. When the
horse insisted that 2 times 2 was 5, he maintained that
it was an example of animal stubbornness. There was
still a simpler method of overcoming inconvenient objec-
tions and that was by ignoring them altogether. The
number 1, the simplest and most fundamental in the
system of numbers, was one of the most difficult for Hans.
(Page 67f.). Mr. von Osten was aware of this, but
thought little of it. During the very first visit of Pro-
fessor Stumpf, Mr. von Osten asked the horse: “ By
how much must you increase the numerator of the frac-

238 THE HORSE OF MR. VON OSTEN

tion 7%, in order to get a whole number?” Hans re-
peatedly answered incorrectly and always tapped num-
bers that were too great. The same question was then
asked concerning the fraction 54, and immediately there
was a correct response, (the favorite number 3). Mr.
von Osten said very naively: “In the case of the differ-
ence of 1, he always goes wrong. It was just what I
expected.” Mr. von Osten still relates that the distinc-
tion between right and left created far greater difficulty
for Hans than all of the work in fractions, and that even
to-day it is not thoroughly established; also, that the se-
lection of colored cloths is often a failure still, although
it was one of the first things in which he was given in-
struction. It appears never to have dawned upon Mr.
von Osten that the arts in which Hans seemed to excel,
also formed the standing repertoire of so many trained
horses, regarding whom it was well-known that they
owed all of their cleverness to the training given them
by their masters. This fact alone should have induced
him to make some form of critical investigation.

When Hans suddenly became a celebrity, and he, him-
self, the object of an enthusiastic following, the whole
affair evidently took Mr. von Osten off his feet. Stran-
gers took the further instruction of the horse in charge,
and the rate and degree of Hans’s progress became dis-
concerting. One day it came to pass that the horse even
understood French, and the old gentleman, whose aposto-
lic exterior had always exerted a high degree of sugges-
tion upon his admirers, in turn fell captive to the spell of
retroactive mass-suggestion. He no longer was uneasy
concerning the most glaring kinds of failure. On one
occasion he even insisted upon the completion of a series
of tests in which procedure was “‘ without knowledge ”,

REACTION OF THE HORSE 239

which promised no results whatever. “ The animal’s stub-
bornness must be broken,” he commented. On the other
hand, he regarded every criticism as a form of personal
insult. And once he showed a member of the committee
of the Society for the Protection of Animals the door, be-
cause the man, without having looked at his watch, wanted
to show it to Hans and ask him the time. Many other
critics had similar experiences.

Summarizing the remarks of this chapter, our judg-
ment must be as follows: It is in the highest degree im-
probable that Mr. von Osten purposely trained the horse
to respond to certain cues. It is also improbable that he
knew that in every test he was giving signals, (although
I can form no judgment concerning what happened after
the publication of the latest report). To assume the
contrary would land us in the midst of insoluble contra-
dictions of the many ascertained facts in the case. The
explanation here essayed, however, should prevent that.
To be sure, we, must then reckon with curious inner
contradictions in Mr. von Osten’s character. But such
contradictions. are to be found, upon earnest analysis, in
nearly every human character. And Mr. von Osten may
say with the poet: “Ich bin kein ausgekliigelt Buch.
Ich bin ein Mensch mit seinem Widerspruch.”

CONCLUSION

If we would make a brief summary of the status of Mr.
von Osten’s horse in the light of these investigations and
try to understand what is the bearing upon the question
of animal psychology in general, we may make the follow-
ing statements.

Hans’s accomplishments are founded first upon a one-
sided development of the power of perceiving the slight-
est movements of the questioner, secondly upon the in-
tense and continued, but equally one-sided, power of at-
tention, and lastly upon a rather limited memory, by
means of which the animal is able to associate perceptions
of movement with a small number of movements of its
own which have become thoroughly habitual.

The horse’s ability to perceive movements greatly ex-
ceeds that of the average man. This superiority is prob-
ably due to a different constitution of the retina, and per-
haps also of the brain.

Only a diminshingly small number of auditory stimuli
are involved.

All conclusions with regard to the presence of emo-
tional reactions, such as stubbornness, etc., have been
shown to be without warrant. With regard to the emo-
tional life we are justified in concluding from the be-
havior of the horse, that the desire for food is the only
effective spring to action.

The gradual formation of the associations mentioned
above, between the perception of movement and _ the
movements of the horse himself, is in all probability not

240

CONCLUSION 241

to be regarded as the result of a training-process, but as
an unintentional by-product of an unsuccessful attempt
at real education, which, though in no sense a training-
process, still produced results equivalent fo those of such
a process.

All higher psychic processes which find expression in
the horse’s behavior, are those of the questioner. His
relationship to the horse is brought about almost wholly
by involuntary movements of the most minute kind. The
interrelation existing between ideas having a high de-
gree of affective coloring and the musculature of the
body, (which is brought to light in this process), is by
no means a novel fact for us. Nevertheless, it is possible
that this case may be of no small value, on account of the
great difficulties which are usually met in the attempt to
establish experimentally the more delicate details in this
field.

And, returning to the considerations of the first chap-
ter, if we ask what contributions does this case make
toward a solution of the problem of animal consciousness,
we may state the following: The proof which was ex-
pected by so many, that animals possess the power of
thought, was not furnished by Hans. He has served to
weaken, rather than strengthen, the position of these en-
thusiasts. But we must generalize this negative conclu-
sion of ours with care—for Hans cannot without fur-
ther qualification be regarded as normal. Hans is a do-
mesticated animal. It is possible (though the opposite is
usually assumed), that our animals have suffered in the
development of their mental life, as a result of the proc-
ess of domestication. To be sure, in some respects they
have become more specialized than their wild kin, (e. g.,
our hunting dogs), and in their habits they have become

242 THE HORSE OF MR. VON OSTEN

adapted largely to suit our needs. This latter is shown
by all the anecdotes concerning “clever” dogs, horses,
etc. But with the loss of their freedom they have also
gradually been deprived of the urgent need of self-preser-
vation and of the preservation of their species, and thus
lack one of the greatest forces that make for psychic
development. And often their artificial selection and
culture has been with a view to the development of muscle
and sinew, fat and wool, all at the expense of brain de-
velopment.* Our horses are, as a rule, sentenced to an
especially dull mode of life. Chained in stalls (and usu-
ally dark stalls at that,) during three-fourths of their
lives, and more than any other domestic animal, enslaved
for thousands of years by reins and whip, they have
become estranged from their natural impulses, and owing
to continued confinement they may perhaps have suffered
even in their sensory life. A gregarious animal, yet kept
constantly in isolation, intended by nature to range over
vast areas, yet confined to his narrow courtyard, and de-
prived of opportunity for sexual activity—he has been
forced by a process of education to develop along lines
quite opposite to his native characteristics. Neverthe-
less, I believe that it is very doubtful if it would have
been possible by other methods, even, to call forth in the
horse the ability to think. Presumably, however, it
might be possible, under conditions and with methods of
instruction more in accord with the life-needs of the
horse, to awaken in a fuller measure those mental activi-
ties which would be called into play to meet those needs.

* Buffon,! the great naturalist, expresses himself not less pessimis-
tically in his own brilliant manner: “Un animal domestique est un
esclave dont on s’amuse, dont on se sert, dont on abuse, qu’on altére,
qu’on dépaise et que l’on dénature.”

CONCLUSION 243

Though our investigations do not give support to the
fantastic acounts of animal intelligence given by Brehms,
they by no means warrant a return to Descartes and his
theory of the animal-machine (as is advocated by a num-
ber of over-critical investigators). We cannot deny the
validity of conclusions from analogy without denying at
the same time the possibility of an animal psychology—
indeed of all psychology. And all such conclusions indi-
cate that the lower forms possess the power of sense-
perception, that they, like us, presumably have at their
disposal certain images, and that their psychic life is to a
large extent also constituted of mere image-associations,
and that they too, learn by experience. Also that they
are susceptible to feelings of pleasure and of pain and
also to emotions, as jealousy, fear, etc., though these
may be only of the kind which have a direct relation to
their life-needs. We are in no position to deny a@ priori
the possibility of traces of conceptual thought in those
forms nearest man in the scale—whether living in their
natural manner or under artificial conditions. And even
less so since the final word has not yet been spoken re-
garding the nature of conceptual thinking itself. All that
is certain is that nothing of the kind has been proven to
occur in the lower forms, and that as yet not even a
suitable method of discovering its existence has been
suggested. But the community of those elementary
processes of mental life which we have mentioned above
is in itself enough to connect the life of the lower forms
with ours, and imposes upon us the duty of regarding
them not as objects for exploitation and mistreatment,
but as worthy of rational care and affection.

SUPPLEMENTS

SUPPLEMENT I
MR. VON OSTEN’S METHOD OF INSTRUCTION
[By C. StumprF]

THE following is a report of the account, which Mr.
von Osten gave Professor Schumann and me, of the
method which he had used in the instruction of the horse,
and which was illustrated by actual demonstrations. I
cannot testify, of course, that Mr. von Osten really did
adhere to this method throughout the four years in which
he tutored the horse, but I will say that I have several
good reasons for believing that it was impossible for him
to have trumped up this make-believe scheme afterward,
merely to mislead us. Among the reasons are the fol-
lowing: He was always ready to give a detailed expla-
nation of any question which we might interpose; the
written statements of Major von Keller, who has known
Mr. von Osten for a period of fifteen years; the testi-
mony of General Zobel, who became acquainted with the
whole process fully a year before any public exhibi-
tions were given; the accounts given by the tenants in
Mr. von Osten’s house, who for years saw the process of
instruction going on in the courtyard of the apartment
building,—according to their account his intercourse with

245

246 THE HORSE OF MR. VON OSTEN

the horse was like that with a child at school,—he made
much use of the apparatus and never did they notice any-
thing like an habituation to respond to certain signals;
and finally the appearance of the apparatus itself—some
of which could not be bought at second hand—was most
convincing.

The apparatus used for the work in arithmetic consisted
mainly of a set of large wooden pins, a set of smaller
ones (such as are to be had in toy-shops), a counting-
machine, such as is commonly used in the schools, a chart
upon which were pasted the numbers from 1 to 100, and
finally the digits, cut large and in brass and suspended
from a string. For the work in reading Mr. von Osten
used the chart shown in the frontispiece of this book.
Here we have the letters of the alphabet in small German
script with numbers written below which serve to indi-
cate the row, and what place in that row, the letters
occupy. For tones, a small, child’s organ was used with
the diatonic scale C! to C?, and for instruction in colors,
a number of colored cloths were used.

The work in arithmetic began by placing a single
wooden pin in front of Hans and then commanding him:
“Raise the foot!—One!” Here we must assume that
the horse had learned to respond to the command to raise
the foot during the preceding period, when tapping in
general had been taught. In order to get the horse to
learn that he was to give only one tap, Mr. von Osten
tried to control the tapping by means of holding the ani-
mal’s foot, just as a teacher tries to aid a pupil in learning
to write by guiding his hand. He repeated this exercise
so often that finally the single tap was made. And al-
ways the right foot was insisted upon. Bread and carrots
were the constant rewards. ;

METHOD OF INSTRUCTION 247

Two of the pins were now set up and the command
given: “ Raise the foot!—One, two!” Mr. von Osten
again aided the establishment of the proper association by
using his hand as before. At the same time the two pins
were pointed out, and the order was always without ex-
ception from left to right. Gradually it became unneces-
sary to touch the foot or to point to the pins, and instead
the question was introduced: “ How many are there? ”, in
order that the horse should become accustomed to these
words as an invitation to give the taps when he saw the
wooden pins before him.

Then three pins were taken and the words “ one, two,
three” were spoken, and so on. In naming a number
the preceding ones were always named along with it, in
order that the normal order might thus be learned at the
same time. Later the number alone, without the preced-
ing ones, sufficed to elicit the proper number of taps.
The last word of the series thus becomes characteristic
of the series as a whole. It differs from all the others,
and thus becomes the sign for the whole series of num-
bers thus named, each of which arises as a memory image
at the proper place in the series and is accompanied by a
tap of the foot. Thus, Mr. von Osten at any rate had
accounted to himself for his success.

But Hans was not to acquire merely this relatively me-
chanical process of counting (hardly to be called count-
ing), but he was to acquire also some meaning content
for the number terms. For this purpose everything de-
pended upon the concept “and”. Only he who can grasp
its meaning will be able to understand a number. 2 is
1 and 1, 3 is 2. and 1. Mr. von Osten had someone hold
a large cloth before the horse, where the wooden pins
usually were placed. He then had the cloth taken uv and

‘

248 THE HORSE OF MR. VON OSTEN

he would pronounce emphatically the word “and”.
After this had been done a number of times, he put up two
of the pins and obscured them by the cloth. The cloth
was again raised‘and the word “and” pronounced. Then
Hans, as a result of his previous instruction (so Mr. von
Osten thought) would give two taps at sight of the pins.
The thing was repeated with three pins, then with one,
and so on, and the horse would always execute the proper
number of taps.

Now, five pins were set up, the three to the right being
covered by the cloth. The horse tapped twice and Mr.
von Osten said “two”. Then the cloth was raised, Hans
gave three further taps, and Mr. von Osten said “and
three” with emphasis.

In this simple manner he tried to get the horse to un-
derstand that the three belongs to the two, and that both
together make five. The image of the five pins as it was
known from previous experience, was to be associated
with the combined groups of two and three, and con-
versely, it was to be reproduced when these groups were
presented. Later the cloth and pins were omitted and the
question was asked: “ How much is two and three?”.
The horse tapped five times. It had learned how to add.
Still this could be regarded only as a mechanical process,
if the horse were able to add only those numbers which
had been presented together one or more times in the
manner just described. And so long as we remained
within the first decade, we could get twenty-five binary
combinations whose sum does not exceed 10 (counting
inverted orders we would have forty-five binary permu-
tations),—all of which might have been practised sepa-
rately. But as a matter of fact, Mr. von Osten did not
take this course, for as he himself says, he allowed Hans

METHOD OF INSTRUCTION 249

to discover a great deal for himself. ‘“ Hans had to de-
velop the multiplication table for himself.”—With larger
numbers and more addends, the number of combinations
becomes so great that there can be no doubt they were
not practised separately.

Since, after all this preliminary instruction, Hans
really began to give solutions of new problems, the master
believed that this was proof that he had succeeded in in-
culcating the inner meaning of the number concepts, and
not merely an external association of memory images
with certain movement responses. But he always re-
mained within the sphere of the ideas thus developed,
and adhered closely to the customary vocabulary and its
usage. Every new concept, each additional word was
explained anew.

It would not be legitimate to condemn the whole pro-
cedure from the very beginning on the ground of the
horse’s lack of knowledge of language or of its use. It
was Mr. von Osten’s aim to convey to the horse an un-
derstanding of the language, by means of sense-presenta-
tions, adequate to give rise to the proper sense-percep-
tions. Helen Keller and other blind deaf-mutes have
been educated to an understanding of the language with-
out the aid of vision and hearing. They have come to it
through the sense of touch alone. Everything depends
upon whether or not the predisposition for it is present.
And it was quite rational that Mr. von Osten should
have chosen counting and arithmetical calculation as the
processes by which to make his attack upon the animal
mind, for as a matter of fact, nowhere else is it so easy
to bridge the gap between perception and conception and
nowhere else can the sign of success or failure be per-
ceived so readily as in the handling of numbers. It is

2:0 THE HORSE OF MR. VON OSTEN

unfortunate, however, that he did not utilize these same
signs for purposes of counter-testing also, as, for in-
stance, by inquiring for the cube root of 729. But he was
prevented from doing this by his close adherence to his
pedagogical principle and by his unquestioning faith in
the soundness of the entire procedure.

In teaching multiplication the counting machine was
used. Two of the ten balls on one of the rods were
pushed far to the left, thus: oo. ‘“ How many are
there?’”” Two taps. “ Very well. That is once two.”
Another group of two was pushed to the left, at a short
interval from the first group, thus: 00 oo. “ How many
times two balls are there?” was asked, with a decided
movement of the hand toward the two groups. Two
taps. “How many, therefore, are two times two?”
Four taps.

The horse was supposed to learn the meaning of the
word “times” by means of the spatial separation of the
groups; he was to be taught to notice and to count the
groups, and also the number of units in a single group.
Three times two then meant three groups with two units
in each group. The horse was supposedly aided by the
following factors: the relative nearness of the units be-
longing to one group, as over against the space interval
between the groups themselves; also that the groups
were pointed out as wholes in connection with the em-
phatic enunciation of the words ‘once, ‘twice, etc.;
and finally the touching and raising of the horse’s foot
by means of the hand until all the desired associations of
the ideas with one another and with the corresponding
tapping movements were quite perfect.

Subtraction was taught in the following manner. Five
pins were set up; the horse tapped five times. Mr. von

METHOD OF INSTRUCTION 251

Osten then removed two of them and said emphatically :
“T take away, — minus. “How many are still stand-
ing?” The horse tapped three times. Here, too, there
was at first some assistance by means of the hand to get
the tapping.

In division four balls were first pushed to the left end
of the rod, thus: o000. “ How many balls are there to
the left?” Four taps. They were now divided into two
pairs, thus: 00 00. Pointing to the units of one group,
the teacher asks: “There are always how many in the
group?” Two taps. Three groups were formed, thus:
0000 00. “ There are now how many balls to the left?”
Six taps. “And there are always how many in each
group?”’, (pointing at them). Two taps. “And how
often is two contained in six?”, (pointing to the groups
consecutively). Three taps, etc.

The ideas of ‘part’, of ‘whole’, and of ‘being con-
tained’ were illustrated by means of a chalk line which
was interrupted in one or more places by erasure.

In all these operations Mr. von Osten adhered strictly
to the rule, and required others to do so too, that the num-
ber upon which the operation was performed, must be
mentioned first. Thus, one was not to say, “take 3 away
from 7”, but “from 7 take away 3.” Otherwise, he be-
lieved, Hans would become easily confused. Also one
was not allowed to say “to multiply”, but to “take” a
certain number so many “times”. He, himself, never
departed from this practice.

We will not go into the details of the method by which
Hans was taught the meaning of the number signs, of the
signs of operation, of the numbers above 10, or the signifi-
cance of “digits”, “tens”, etc. Only this,—when in
problems in addition the sum was greater than Io, the 10

252 THE HORSE OF MR. VON OSTEN

was first tapped and then the remainder of the number
added to the 10. Thus: “ You are to add 9 and 5. How
much must you add to the 9 to have 10?” One tap.
“ But now, you were to add not merely 1, but 5; how
much have you still to add to the 10? ”—Four taps. In
like manner, whenever the addends were below 20 or 30
and the sum above 20 or 30, Mr. von Osten would ask
for the 20 or 30 taps first. He thought that he was thus
giving his pupil an ever firmer grasp upon the principle
of the structure of our number system, in which all higher
numbers are constituted of tens and digits. For the
same reason he used at first, instead of the words ‘ eleven’
and ‘twelve’ (‘elf’ and ‘zwolf’ in the German), ex-
pressions which in English might be rendered as ‘ one-
teen’ and ‘two-teen’ (‘einzehn’ and ‘ zweizehn’ in the
German) ; and only later, after the animal had seemingly
mastered the meaning in question, did Mr. von Osten re-
place them by the usual forms.

All this was beautifully conceived and might perhaps
form the basis for the instruction of primitive races.
But it is of immediate interest for us only because it
enables us to better understand the origin of the con-
viction under which Mr. von Osten and his followers
labored.

SUPPLEMENT II
THE REPORT OF SEPTEMBER 12, 1904

“THE undersigned came together for the purpose of
investigating the question whether or not there is in-
volved in the feats of the horse of Mr. von Osten any-
thing of the nature of tricks, that is, intentional influ-
ence or aid, on the part of the questioner. After a care-
ful investigation they are unanimously agreed that such
signs are out of the question under the conditions which
were maintained during this investigation. This decision
in no wise takes into account the character of the men
exhibiting the horse, and who are known to most of the
undersigned. In spite of the most attentive observation,
nothing in the way of movements or other forms of ex-
pression which might have served as a sign, could be dis-
covered. In order to obviate involuntary movements on
the part of those present, one series of tests was made
with only Mr. Busch present. Among these tests were
some in which, according to his professional judgment,
the possibility of tricks of the sort commonly used in
training, was excluded. Another series of tests was made
in such a way that the correct answers to the questions
which Mr, von Osten put to the horse, were unknown to
the questioner. From previous observation the greater
number of the undersigned also know of a large number
of cases in which, during the absence of Mr. von Osten
and Mr, Schillings, other persons were likewise able to
obtain correct responses from the horse. Among these

253

254 THE HORSE OF MR. VON OSTEN

were some cases in which the questioner did not know
the correct solution of the problem or was mistaken about
it. And lastly, several of the undersigned have become
acquainted with the method which Mr. von Osten used,
which has little in common with methods of training, and
is patterned after the instruction given in the elementary
schools. As a result of these observations the under-
signed are of the opinion that unintentional signs of the
kind which are at present familiar, are likewise excluded.
They are unanimously agreed that this much is certain:
This is a case which appears in principle to differ from
any hitherto discovered, and has nothing in common with
training, in the usual sense of that word, and therefore
is worthy of a serious and incisive investigation.

BERLIN, September 12, 1904.

Paul, BuscH, Circus-manager.

Orro, CounT zu CASTELL-RUDENHAUSEN.

Dr. A. GRaBow, member of the schoolboard, retired.

RoBERT Haun, Teacher, Municipal schools.

Dr. Lupwic HECK, Director of the Zodlogical Garden.

Dr. OscaR HEINROTH, Assistant in the Berlin Zod-
logical Garden.

Dr. RICHARD KANDT.

Major F. W. von KELLER, retired.

Major-GENERAL TH. KORING, retired.

Dr. MIEssNER, Assistant in the Royal Veterinary
College.

ProF. NAGEL, Head of the department of sense-physi-
ology in the Physiological Institute of the Univer-
sity of Berlin.

Pro. C. Stumpr, Director of the Psychological In-
stitute, Member of the Academy of Sciences.

HENRY SUERMONDT,”’

SUPPLEMENT III

AN ABSTRACT FROM THE RECORDS OF THE
SEPTEMBER-COMMISSION *

THE important meetings occurred on the 11th and
12th of September and both of them extended over four
hours. The greatest difficulty was occasioned by the con-
dition laid down by Mr. von Osten: that we were to work
without him from the very beginning. Ina certain sense
this condition had been met once before when Mr.
Schillings appeared upon the scene, a man whose fair-
ness ought to be doubted by none. He came utterly
skeptical, and yet in the course of a week he learned
to handle the horse and received responses regularly.
However, since the public had begun to doubt Mr.
Schillings also, another person had to attempt the rdle
of questioner. Count zu Castell tried to do this and
practised for some days before the meetings, but his
success—although of no small moment—was not great
enough to be convincing.

In apprising Mr. von Osten of this fact we caused a
veritable catastrophe. He declared in a most decisive
manner that he would have to insist upon the condition

* A few days after the 12th of September I made the present abstract
from the original records af the Commission, which I have here ab-
breviated somewhat. (See page 8). Referring once more to the misun-
derstanding mentioned on page 3, I would say that the closing sentence
of the report is here re-given literally as it then appeared. C. St.

255

256 THE HORSE OF MR. VON OSTEN

he had imposed, since the public demanded it, and he
could never assist in any tests, until he had been cleared
of the suspicion of having descended to the use of tricks,
If it should take weeks to accustom the horse to a new
questioner, there would be no alternative but to wait
that length of time.

A happy circumstance helped us out of our difficulty.
We had chanced in our discussion to mention the ex-
perience of Dr. Miessner, a member of the commission,
who on the day before had gone to witness an exhibition
of the mare “Clever Rosa”, and who believed that
he had succeeded in discovering the tricks involved.
There was a sudden change in Mr. von Osten’s attitude.
He expressed his willingness to undergo the most strin-
gent examination and agreed to anything in the way of
conditions of control, challenging even the proven ability
of Dr. Miessner. “I have neither whip nor rod, as had
the man in the exhibition, and agree to any precautionary
measures you may care to take.”

After he had gone, the commission decided to ask him
to have the horse perform one of the more common,
simple, feats. They were going to watch him very
closely. Different members were assigned the task of
attending to different parts of his body (head, eyes, right
hand, left hand, etc.) while Mr. Busch, since he was the
most proficient in the detection of tricks, was to regard
the total behavior of the man.

The exhibitions included the indication of the day of
the week by means of taps, the day just past, the day
ahead, its date, arithmetical problems, and the counting
of rings strung upon a rod. Messrs. Grabow and Hahn
interpolated a few tests themselves, in which they did the
questioning. All tests were successful.

THE SEPTEMBER-COMMISSION 257

Mr. von Osten withdrew, and in comparison of notes
which followed, Mr. Busch, as well as all the others,
declared that they had discovered nothing of the nature
of a visible sign. Mr. Busch said that he had also kept
an eye on the spectators and had noticed nothing there.
Nevertheless, he desired to see Mr. von Osten go through
one series with no one else but himself (Busch) present.

This was done, and on this occasion a number of tests
were made in the recognition of colored cloths. The
horse was required to indicate, by tapping, the place in
the series which the cloth occupied and was then asked
to bring the green or the red, as the case might be, in
his mouth. Furthermore, he was asked to approach that
one of the five gentlemen standing at a distance, whose
photograph had been shown him. Then he was requested
to spell the words “ Rat” and “ Busch” according to the
method which he had been taught. Nearly all of these
tests were likewise successful.

In the conference which followed, Mr. Busch again
declared that he had noticed no trace of a sign; he main-
tained that, in the selecting of colored cloths (especially
when they were placed so closely together) and in the
approach toward a person, there was no possibility what-
ever that some trick was being used.

During the session of September 12th, Mr. von Osten
agreed to two sets of experiments.

1. Another man was to put the question to the horse.
Mr. von Osten himself was to stand, back to back to the
questioner and to bend forward, so that he was effectually
hidden from the horse’s view, yet could, by means of
occasional calls, make his presence known to the animal.
The assumption was that it would be conducive to suc-
cess if the horse knew that the master was present and

258 THE HORSE OF MR. VON OSTEN

was awaiting the answer, and yet at the same time the
possibility of receiving a sign was obviated.

2. Another man in Mr. von Osten’s absence was to
ask the horse to tap a certain number. Then the ques-
tioner was to leave, and Mr. von Osten, returning, was
to ask the horse to perform some arithmetical process
with the number which was thus unknown to the master.
Mr. von Osten said that he thought that this method was
somewhat risky, since the horse would be aware that he,
Mr. von Osten, did not know the number, and might
therefore be in a humor to play some prank.

The questions of the first sort were answered with
but very few errors. Mr. Hahn and Count zu Castell
asked simple questions in arithmetic: When Mr. von
Osten withdrew into the stable, the count put several
other problems, among them the counting of persons
and of windows, all of which were solved correctly.

Between the first and second series of tests the follow-
ing experiments were interpolated. The names of six
members of the commission were written upon six slates
respectively, which were then suspended from a string.
Mr. von Osten pointed to one of the men and asked:
“On which of the slates is this gentleman’s name to be
found?”. The correct number was tapped in every case.
The command to approach the slate in question was also
obeyed as a rule, although this was not as uniformly suc-
cessful as tapping.

In the conference which followed, Mr. Busch declared
that the feats appeared inconceivable to him; and again
none of the men had noted anything in the way of signs.

Now followed the second series of tests mentioned
above. In order to be sure to get the correct responses,
Mr. Schillings, who up to this point had not been present

THE SEPTEMBER-COMMISSION 2x9

at any of the experiments, was asked to put the questions
to the horse. Mr. von Osten went into the house, accom-
panied by a member of the commission. And again, Mr.
Schillings would go out before the second part of the
test, without having met Mr. von Osten.

Five tests were made in this way. They were not
attended by such amazing success as were the preceding
ones, but nevertheless the results were surprising. The
horse nearly always repeated the number itself, instead
of performing the operation required. Since, however,
Mr. Schillings, owing to a misunderstanding, had, in the
first two cases, said to the horse: “ You are to repeat
this number for Mr. von Osten”, the errors might appear
to be a result of this request.

At the final discussion, the result of which was the
unanimous declaration which was given for publication,
not only the data obtained during these two sessions, but
also the earlier experiences of some of the members of
the commission were taken into consideration. None of
the tests witnessed could be referred to chance or to the
use of tricks. Count zu Castell pointed out that in the
course of eight days he had elicited forty correct
responses from the horse, among them some in regard
to which he himself had been momentarily in error.
Other members recalled the many instances in previous
exhibitions, during which both Mr. Schillings and Mr.
von Osten were absent, when questions were put to the
horse by others. The commission also had access to a
detailed account written by Professor Stumpf on Mr.
von Osten’s method of instruction, based on the ex-
planations and demonstrations which Mr. von Osten
had himself given. As a result of these considerations
the commission felt under obligations to give public

260 THE HORSE OF MR. VON OSTEN

expression to its conviction. In the report it limited
itself, however, to the purely negative side—principally
in denying the use of tricks,—and expressed no opinion
with regard to the actual genesis of the horse’s accom-
plishments, since it believed that there was great possibil-
ity that other factors were involved which ought to be
carefully investigated.

SUPPLEMENT IV
THE REPORT OF DECEMBER or, 1904

ToGETHER with Dr. E. von Hornbostel and Mr. O.
Pfungst, I have tried during the past few weeks to find
an explanation of the accomplishments of the horse
‘Hans’ by the experimental method. We had access
to the horse in the absence of the master and groom.
The results are as follows:

The horse failed in his responses whenever the solution
of the problem that was given him was unknown to any
of those present. For instance, when a written number
or the objects to be counted were placed before the
horse, but were invisible to everyone else, and especially
to the questioner, he failed to respond properly. There-
fore he can neither count, nor read, nor solve problems
in arithmetic.

The horse failed again whenever he was prevented by
means of sufficiently large blinders from seeing the per-
sons, and especially the questioner, to whom the solution
was known. He therefore required some sort of visual
aid,

These aids need not, however,—and this is the peculi-
arly interesting feature in the case—be given inten-
tionally. The proof for this is found in the fact that in
the absence of Mr. von Osten the horse gave correct
replies to a large number of persons; and to be more
specific, Mr. Schillings and later Mr. Pfungst, after

261

262 THE HORSE OF MR. VON OSTEN

working with the horse for a short time, regularly re-
ceived correct answers, without their being in any way
conscious of having given any kind of signal.

So far as I can see, the following explanation is the
only one that will comport with these facts. The horse
must have learned, in the course of the long period of
problem-solving, to attend ever more closely, while
tapping, to the slight changes in bodily posture with
which the master unconsciously accompanied the steps
in his own thought-processes, and to use these as closing
signals. The motive for this direction and straining of
attention was the regular reward in the form of carrots
and bread, which attended it. This unexpected kind of
independent activity and the certainty and precision of
the perception of minimal movements thus attained, are
astounding in the highest degree.

The movements which call forth the horse’s reaction,
are so extremely slight in the case of Mr. von Osten, that
it is easily comprehensible how it was possible that they
should escape the notice even of practised observers.
Mr. Pfungst, however, whose previous laboratory ex-
perience had made him keen in the perception of visual
stimuli of slightest duration and extent, succeeded in
recognizing in Mr. von Osten the different kinds of
movements which were the basis of the various accom-
plishments of the horse. Furthermore, he succeeded in
controlling his own movements, (of which he had
hitherto been unconscious), in the presence of the horse,
and finally became so proficient that he could replace
these unintentional movements by intentional ones: He
can now call forth at will all .the various reactions
of the horse by making the proper kind of. voluntary
movements, without asking the relevant question or

REPORT OF DECEMBER ory, 1904 —-263

giving any sort of command. But Mr. Pfungst meets
with the same success when he does not attend to
the movements to be made, but rather focuses, as
intently as possible, upon the number desired, since
in that case the necessary movement occurs whether he
wills it or not. In the near future he will give a special
detailed report of his observations, which gives promise
of becoming a valuable contribution to the study of in-
voluntary movements. Also he will give an account of
our tests and of the mechanism of the various accomplish-
ments of the horse. We must also defer, till then, the
disproof of certain seemingly relevant arguments in favor
of the horse’s power of independent thought.

Some defenders of the view which maintains the
horse’s rationality may urge that it was only through
our experiments that the animal became trained and
spoiled in so far as the ability to think is concerned.
They are refuted in this, however, by the fact that the
horse still continues to solve problems involving decimal
fractions and to determine calendar dates for Mr. von
Osten, as brilliantly as ever, as is shown by his recent
demonstration before a large group of spectators. That
these results are now being achieved in a manner essen-
tially different from formerly is nothing but a bare asser-
tion.

On the other hand, now that the possibility has been
established that these wonderful results may be obtained
in all their complexity by means of intentional signs,
many will question whether Mr. Von Osten did not
himself train the horse from the very beginning to
respond to these signs. No one has the right, how-
ever, to charge an old man, who has never had a blemish
on his reputation, with having invented a most refined

264 THE HORSE OF MR. VON OSTEN

network of lies, if the facts can be explained in a satis-
factory manner in some other rational way. And this
can be done in this case. For we have seen that there
is another alternative, other than the theory that the
horse can think or the assumption that tricks have been
employed.

And now, aside from the specific results obtained,
what is the scientific and philosophic import of the whole
affair?—-For one thing, the revolution in our conception
of the animal mind, which had been hoped for by some,
and feared by others, has not taken place. But a con-
clusion of an opposite character is justified. If such un-
exampled patience and high pedagogical excellence as
was daily brought to bear by Mr. von Osten during the
course of four long years, could not bring to light the
slightest trace of conceptual thinking, then the old asser-
tion of the philosophers that the lower forms are incapable
of such thinking, finds corroboration in the results of
these experiments so far as the animal scale up to and in-
cluding the ungulates is concerned. For this reason the
tremendous effort put forth by Mr. von Osten, is not,
in spite of the self-deception under which he labors, lost
to science. If anyone has the courage to try the experi-
ment with the dog or the ape, the insight which we have
now gained will enable him to beware of one source of
error which hitherto has not been noticed.

In the face of much misapprehension which has arisen,
I wish once more to say emphatically that the committee
of September 12th in no wise declared itself to be con-
vinced that the horse had the power of rational thinking.
The committee restricted itself entirely to the question
whether or not tricks were involved, and, intentionally
and rightly referred the positive investigation to a purely

REPORT OF DECEMBER orn, 1904 265

scientific court. I would also report that for some time
Mr. Schillings has been convinced, by his own observa-
tions, of the horse’s lack of reason, and when he was
apprised of our conclusion in the matter, he embraced it
without wavering. I have no intention of taking part
in any discussion which may arise in the press as a result
of the present report. Unless they wish to confine them-
selves to mere guesswork, the defenders of other views
will not shrink from the task of basing their criticism
upon careful methodical experimentation, and they will
keep a detailed record of their results day by day; for
statements based solely upon memory, without specific
report of experimental conditions, prove nothing.
Pror. CaRL STUMPF.
December gth, 1904.

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(The names of the authors of anonymous works are placed in parenthesis.)

I.

12.

13.

ZELL, TH. Das rechnende Pferd. Ein Gutachten iiber den
“Klugen Hans ” auf Grund eigener Beobachtungen. Berlin,
R. Dietze, 1904.

FREUND, F. Der “kluge” Hans? Ein Beitrag zur Aufklarung.
Berlin, Boll and Pickardt, 1904.

Hansen, F. C. C. and A. Lehmann. Uber unwillkiirliches
Fliistern. Philosophische Studien, edited by W. Wundt,
Leipsic, 1895, Vol. 11, pp. 471 ff.

SANDEN, S. v. Uber Aktivitat und Passivitat des Reiters und
seiner Hiilfen. Deutsche hippologische Presse, Berlin, 1896,
Jahrg. 12, No. 11, pp. 117 ff. and No. 12, pp. 128 ff.

WEYER, E. M. Some Experiments on the Reaction-Time of
a Dog. Studies from the Yale Psychological Laboratory,
New Haven, Conn., 1895, Vol. 3, pp. 96 f.

DopcE, R. Die motorischen Wortvorstellungen. Hallea.S., M.
Niemeyer, 1896, pp. 40 and 77.

Darwin, Cuas. The Expression of the Emotions in Man and
Animals. New York, D. Appleton & Co., 1873, pp. 273 ff.

Wunpbt, W. Volkerpsychologie. Leipsic, W. Engelmann, r9goo,
Vol. x, Part I, pp. 175 f.

LieBER, F. On the Vocal Sounds of Laura Bridgeman. Smith-

-gonian Contributions to Knowledge, Washington, 1851, Vol.
2, Art 2, pp. 11 f. (Laura wrote her name: Bridgman.)

Garner, R. L. The Speech of Monkeys. New York, Chas.
Webster & Co., 1892, pp. 57 ff.

Fért, Cuas. Sensation et mouvement. Paris, F. Alcan, 1887,
pp. 102 f.

James, W. The Principles of Psychology. New York, Henry
Holt & Co., 1890, Vol. 2, pp. 372 and 381.

Bearp, G. M. The History of Muscle-Reading. Journal of
Science, and Annals of Astronomy, Biology, Geology, etc.,
London, 1881, Series 3, Vol. 3, p. 558 f.

267

268

14.

15.

16.

17.

18,

19.

20.

21.

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23.
24.
25.

26.

27.

TABLE OF REFERENCES

LauRENT, L. Les procédés des liseurs de pensées. Journal de
psychologie normale et pathologique, Paris, 1905, second
year, No. 6, pp. 489 f.

GuiccraRDI, G. e G. C. FERRARI. II lettore del pensiero “ John
Dalton.” Rivista sperimentale di Freniatria ecc., Reggio
nell’ Emilia, 1898, Vol. 24, p. 209.

TARCHANOF?Y, J. de. Hypnotisme, suggestion et lecture de pen-
sées. Translated from the Russian by E. Jaubert, second
edition. Paris, G. Masson, 1893, pp. 153 ff.

PREYER, W. Telepathie und Geisterseherei in England. Deut-
sche Rundschau, Berlin, 1886, Jahrg. 12, Heft 4, p. 4o.
SomMER, R. Dreidimensionale Analyse von Ausdrucksbeweg-
ungen. Zeitschrift fiir Psychologie und Physiologie der

Sinnesorgane, Leipsic, 1898, Vol. 16, pp. 280 ff.

FRENKEL, H. Des secousses rhythmiques de la téte chez les
aortiques et chez les personnes saines. Revue de Médecine,
Paris, 1902, 22nd Year, No.7, pp. 617 ff.

ZoneFF, P. and E. Meumann. Uber Begleiterscheinungen
psychischer Vorginge in Atem und Puls. Philosophische
Studien, edited by W. Wundt, Leipsic, 1903, vol. 18, p. 3.

MULLER, G. E. and A. PILZEcKER. Experimentelle Beitrage zur
Lehre vom Gediachtniss. Zeitschrift fur Psychologie und
Physiologie der Sinnesorgane, Leipsic, 1900, Erganzungsband
1, pp. 58 ff.

KRAEPELIN, E. Der psychologische Versuch in der Psychiatrie.
Psychologische Arbeiten, edited by the same, Leipsic, 1895,
Vol. 1, pp. 50 ff.

Ampexrc, E. Uber den Einfluss von Arbeitspausen auf die
geistige Leistungsfahigkeit. Ditto, pp. 374 ff.

SHALER, N.S. Domesticated animals. London, Smith Elder &
Co., 1896, pp. 143 ff.

Courin, H. L’esprit des animaux domestiques. La Revue,
Paris, 1903, first quarter, Vol. 44, p. 586.

(LEBRUN, P.). Lettres qui découvrent ]’illusion des philosophes
sur la baguette, et qui détruisent leurs systémes. Paris, J.
Boudot, 1696, pp. 239 ff.

Notice sur un nouvel instrument, dont Mr. Ritter, membre de
V’académie de Munich s’est servi dans les expériences qu'il a
récemment faites avec Mr. Campetti etc. Bibliothéque
Brittannique, Sciences et Arts, Geneva, 1807, Vol. 35,
Pp. 9.

28.

29.

30.

31.

32.

33:

4

36.

37.

38.

39-

40.

TABLE OF REFERENCES 269

ZeLL, TH. Tierfabeln und andere Inrrtiimer in der Tierkunde.
2nd edition. Stuttgart, Kosmog (1905), p. 38.

THORNDIKE, E,L. Animal Intelligence. Psychological Review,
Lancaster, Pa. and New York, 1898, Monograph Supple-
ments, Vol. z, No. 4, p. 95.

VASCHIDE, N. et P. Rousseau. Etudes expérimentales sur la
vie mentale des animaux. Revue scientifique, Paris, 1903,
Series 4, Vol. 19, No. 25, p. 782.

ETTLINGER, M. Sind die Tiere verniinftig? Hochland, Munich
and Kempten, 1904, Jahrg, 2, Heft 2, p. 223.

RomaneEs, G.J. On the Mental Faculties of the Bald Chimpanzee
(Anthropopithecus calvus). Proceedings of the Scientific
Meetings of the Zoological Society of London, 1889, pp.
320 f.

KinnaMAN, A. J. Mental Life of two Macacus rhesus Monkeys
in Captivity. American Journal of Psychology, Worcester,
Mass., 1902, Vol. 13, No. 1, pp. 139 ff.

HIMSTEDT, Fr. and W. A. NaGEL. Versuche iiber die Reiz-
wirkung verschiedener Strahlenarten auf Menschen- und
Tier- augen. Festschrift der Albrecht-Ludwigs-Universitat
in Freiburg zum 50 jahrigen Regierungs-Jubilaum Sr. Konigl.
Hoheit des Groszherzogs Friedrich. Freiburg i. Br., C. A.
Wagner, 1902, pp. 272 ff.

Dau, F. Naturwissenschaftliche Wochenschrift, Jena, 1905,
New series, Vol. 4, No. 48, pp. 767 ff.

CorTE, CLaupIo. II cavallerizzo. Di nuove dall’ auttore stesso
corretto ed emendato. Venice, G. Ziletti, 1573, Book 1,
Chap. 6, page 8. (I did not have access to the first edition
of 1562, cf. Graesse, Trésor de livres rares, 1861, Vol. 2, p.
277.)

RIEGEL. Untersuchungen iiber die Ametropie der Pferde.
Monatshefte fiir praktische Tierheilkunde, Stuttgart, 1904,
Bd. 16, Heft 1, pp. 31 ff.

Breruin, R. Uber die Schatzung der Entfernungen bei Tieren.
Zeitschrift fiir vergleichende Augenheilkunde, Wiesbaden,
1891, Bd. 7, Heft 1, pp. 5 f.

THE SAME. Uber ablenkenden Linsen-Astigmatismus und seinen
Einfluss auf das Empfinden von Bewegung. Ditto, 1887, Bd.
5, Heft 1, pp. 7 ff.

ScHLEICH, G. Das Sehvermégen der héheren Tiere. Tiibingen,
F. Pietzcker, 1896, p. 24.

270

41.

42.

47:

48a.

TABLE OF REFERENCES

Konicsuover. Uber das Augen des Wildes. Monatshefte des
Allgemeinen Deutschen Jagdschutz-Vereins, Berlin, 1898,
Jahrg. 3, No. 17, pp. 250 f.

ZuRN, J. Vergleichend histologische Untersuchungen iiber die
Retina und die Area centralis retina der Haussdugetiere.
Archiv fur Anatomie und Physiologie, Anatomische Ab-
teilung, Leipsic, 1902, Supplementary volume, pp. 116 ff.

HIRSCHBERG, J. Zur vergleichenden Ophthalmoskopie. Archiv
fur Anatomie und Physiologie, Physiologische Abteilung,
Leipsic, Jahrg. 1882, p. 96.

BERLIN, R., see 39, p. 4-

Tue same. Uber den physikalisch-optischen Bau des Pferdeauges,
Zeitschrift fur vergleichende Augenheilkunde, Leipsic, 1882,
Jahrg. 1, Heft 1, p. 32.

Bayer, J. Tierarztliche Augenheilkunde. Vol. 5 of the “ Hand-
buch der Tierdrztlichen Chirurgie und Geburtshilfe” by J.
Bayer und E. Fréhner. Vienna und Leipsic, W. Braumiiller,
1900, p. 459.

THE SAME. Ditto, p. 475.

RIEGEL, see 37, p. 35-

SCHWENDIMANN, F. Untersuchungen iiber den Zustand der
Augen bei scheuen Pferden. Archiv fiir wissentschaftliche und
praktische Tierheilkunde, Berlin, 1903, Bd. 29, Heft 6, p. 566.

. BERLIN, R. Refraktion und Refraktionsanomalien von Tieraugen.

Tageblatt der 52. Versammulung deutscher Naturforscher
und Arzte in Baden-Baden, 1879, p. 348. See also 45, pp. 28 f£.
and 39, p. 13.

THE SAME, see 39, p- 9.

BAYER, J., see 46, pp. 460 f.

ZURN, J., see 42, p. 114.

Curevitz, J. H. Uber das Vorkommen der Area centralis retin
in den vier héheren Wirbeltierklassen. Archiv fiir Anatomie
und Physiologie, Anatomische Abteilung, Leipsic, 1891, Heft

.. 47 P- 329

ZuRN, J., see 42, p. 140.

KONIGSHOFER, see 41, pp. 251 ff.

TENNECKER, S. v. Bemerkungen und Erfahrungen iiber den
Charakter und das Temperament, sowie iiber die geistigen
Eigenschaften des Pferdes iiberhaupt. Beitrige zur Natur-
und Heilkunde, von Friedreich und Hesselbach, Wiirzburg,
1825, Vol. 1, pp. 110 f.

56.

5?
38.

59.

71,

72.

TABLE OF REFERENCES 271

ZBORZILL, E. Die mnemonische Dressur des Hundes. Berlin,
S. Mode (1865), p. 21. *

Mier, AD. und K. Tiere der Heimat. 3rd Edition, Cassel,
Th. Fischer, 1897, Book 1, p. 70.

HurcuHinson, W.N. Dog Breaking. 6th Edition, London, J.
Murray, 1876, pp. 105 f.

Huceins, Lapy M. Kepler: a Biography. Cited by Sir J.
Lubbock, On the Senses, Instincts, and Intelligence of
Animals. London, Kegan Paul, Trench and Co., 1888,
pp. 284 f. (The original was published privately and never
put on the market. Hence it was not accessible for
me.)

Luszock, SiR J. Ditto, p. 285.

RouHET, G. L’entrainement complet et expérimental de l’hom.
me avec étude sur la voix articulée, suivi de recherches phy-
siologiques et pratiques sur le cheval. Paris, Libraires as-
sociés, and Bordeaux, Feret et fils, 1902, pp. 517 ff.

. Lipps, TH. Zur Psychologie der Suggestion. Leipsic, J. A.

Barth, 1897, pp. 5 f.

ZELL, TH. See 1, pp. 4o f.

ZBORZILL, E. See 56, p. 23.

Bearp, G. M. Physiology of Mind-Reading. Popular Science
Monthly, New York, February 1877. Vol. 10, p. 472.
Reprint in the Journal of Science, and Annals of Astronomy,
Biology, Geology, etc., London, 1881, Series 3, Vol. 3, p. 418.

BaBINET. Les tables tournantes au point de vue de la mécanique
et de la physiologie. Revue des deux mondes, Paris, 1854,
Twenty-fourth year, Vol. 5, pp. 409 f.

Totsto1, L.N. Anna Karenina.

GoLpBECK. Besitzen die Tiere, speziell Hunde, Verstand oder
nicht? Deutsche tierarztliche Wochenschrift, Hannover,
1902, Jahrg. 10, No. 20, p. 202.

MENAULT, E, Liintelligence des animaux. 4th Edition, Paris,
Hachette et Cie., 1872, p. 233.

LeBon, G. L’equitation actuelle et ses principes. 3rd Edition,
Paris, Firmin-Didot et Cie., 1895, pp. 120 and 288.

Lorset, B. Praktischer Unterricht in Kunstdarstellungen mit
Pferden. New edition. Stuttgart, Schickhardt u. Ebner,
1884, pp. 69 f. and 98 ff.

BaucHER, F. Dictionnaire raisonné d’équitation. 2nd Edition,
Paris, chez l’auteur, 1851, pp. 291 ff.

272

86.

87.
88.

89.

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ARNIM, v. Praktische Anleitung zur Bearbeitung des Pferdes an
der Longe. 2nd Edition, Leipsic, Zuckschwerdt und Co,
1896, pp. 18 f. and 39 f.

MEEHAN, J. The Berlin “ Thinking” Horse. Nature, London.
1904, Vol. 70, No. 1825, p. 602.

Spour. Die Logik in der Reitkunst. Part z. Pamphlet No. 32
in the Series: “Unsere Pferde.” Stuttgart, Schickhardt
und Ebner, 1904, p. 29 f.

REDDING, T. B. The Intelligence of a Horse. Science, New
York, 1892, Vol. 20, No. 500, pp. 133 f.

Spour. Die naturgemasze Gesundheitspflege der Pferde. 4th
Edition, Hannover, Schmorl u. v. Seefeld Nachf., 1904,
p. 164.

Decroix, E. Projet de langage phonetique universe] pour la
conduite des animaux. Bulletin de la Société nationale
d’Acclimatation de France, Paris, 1898, Forty-fourth Year,
pp. 241 ff.

NoizEt, GENERAL. Etudes philosophiques. Paris, H. Plon,
1864, Vol. 1, pp. 471 ff.

Bearp, G.M. See 65, Vol. 10, p. 471.

LeBon, G. See 70, p. 120.

FLUGEL, O. Das Seelenleben der Tiere. 3rd Edition, Langen-
salza, H. Beyer und Séhne, 1897, pp. 50 f.

Lanvots, H. Uber das musikalische Gehor der Pferde. Zeit-
shrift fiir Veterinirkunde, Berlin, 1889, Jahrg. 1, No. 6.
pp. 237 ff.

FovEAU DE COURMELLES. Les facultés mentales des animaux,
Paris, J. B. Bailliére et fils, 1890, p. 142.

Zurn, F. A. Die intellektuellen Eigenschaften (Geist und Seele)
der Pferde. Pamphlet 8 of the Series: “Unsere Pferde.”
Stuttgart., Schickhardt und Ebner, 1899, p. 26.

Fixuis, J. Tagebuch der Dressur. Translated from the French
by J. Halperson and G. Goebel. Stuttgart, Schickhardt und
Ebner, 1906, pp. 322 f.

ATHENAEUS. Dipnosophistae. Book 12, 520 c. Edited by G.
Kaibel. Leipsic, B. G. Teubner, 1890, Vol. 3, pp. 148 £.
AELIANUS, CL. De natura animalium. Book 16, 23. Edited by

R. Hercher. Leipsic, B. G. Teubner, 1864, Vol. 1, p. 401.

Jutius AFricaNnus, S. Keoroi, chapter 14. In: Veterum
Mathematicorum Opera. Paris, Typographia Regia, 1693,
P- 293.

gl.

93-

94.

95

1ol.

102,

103.

104.

105.

106,

TABLE OF REFERENCES 273

Gutnon, A. Influence de la musique sur les animaux et en par-
ticulier sur le cheval. (Chalons-sur-Marne), 1898, pp. 83 ff.

Lépinay. L’hypnotisme chezle cheval. Revue de l’hypnotisme,
Paris, 1903, Eighteenth Year, No. 5, pp. 152 f.

Fits, J. Grundsatze der Dressur und Reitkunst. Translated
from the French by G. Goebel. 3rd Edition, Stuttgart,
Schickhardt und Ebner, 1905, pp. ro f.

Manouvrler, L. Mouvements divers et sueur palmaire consé-
cutifs 4 des images mentales. Revue philosophique, Paris,
1886, Vol. 22, pp. 204 ff.

GASPARIN, CTE A. DE. Des tables tournantes, du surnaturel en
général et des esprits. 2nd Edition, Paris, E. Dentu, 1855,
Vol. 1, Part 1.

Rivers, W. H. R. and E. Krarpetin. Uber Ermiidung and
Erholung. Psychologische Arbeiten, edited by E. Kraepelin,
Leipsic, 1895, Vol. 1, pp. 636 f.

(CARPENTER, W. B.). Spiritualism and its Recent Converts.
Quarterly Review, London, 1871, Vol. 131, No. 262, p. 312.

Darwin, Cuas. See 7, p. 48.

SAINT-ANGE, DE. Cours d’hippologie. 2nd Edition, Paris, chez
Dumaine et chez Leneveu and Saumur, chez Mlle. Niverlet
et chez Mlle. Dubosse, 1854, Vol. 1, p. 101.

Franzius, G. Die Wiinschelrute. Zentralblatt der Bauverwal-
tung, Berlin, 1905, Jahrg. 25, No. 74, pp. 461 f.

MENESTRIER, CL. Fr. La philosophie des images énigmatiques.
Lyon, J. Guerrier, 1694, pp. 483 f.

(LeBrun, P.). Histoire critique des pratiques superstitieuses,
qui ont séduit les peuples et embarassé les scavans. Paris
(et Amsterdam), 1702, p. 42.

AcricoLa, G. De re metallica libri XII, eiusdem de animantibus
subterraneis liber. Basel, Froben, 1556, Book 2, pp. 27 f.
Scuott, C. Magia universalis nature et artis. Wiirzburg, J. G.

Schénwetters Erben, 1659, Part 4, Book 4, p. 430.

THE sAME. Physica curiosa, sive mirabilia naturae et artis.
Wiirzburg, 1662, Part 2, Book 12, p. 1532.

ZEIDLER, J.G. Pantomysterium, oder das Neue vom Jahre in
der Wiinschelruthe, etc. Hall in Magdeburg (Halle a. S.),
Renger, 1700, Chap. 2. p. 47.

Barrett, W. F. On the so-called Divining Rod, or Virgula
Divina. Proceedings of the Society for Psychical Research,

London, 1897, Vol. 13, pp. 177 f.

274
107.
108,
109.
110.
Iil,
112.
113.

114.

115.
116.
117.

118,

119.
120.

121.
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123.
124.

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THEOPHANES. Chronographia. Paris, Typographia Regia, 1655,
pp. 189 f.

Youatt, W. The Dog. London, Ch. Knight and Co. 1845,
pp. 108 ff.

TarRADE, E. DE. Traité de l’élevage et de l’éducation du chien.
Paris, E. Lacroix (1866), pp. 113 ff.

HACHET-SOUPLET, P. Die Dressur der Tiere. Translated from
the French by O. Marschall v. Bieberstein, Leipsic, O. Klemm,
1898, pp. 36 f.

LusBzock, Sir J. See 59, pp. 280 f.

Ltonarp, A. Essai sur I’éducation des animaux, le chien pris
pour type. Lille, Leleux, 1842, pp. 81-185.

MEEHAN, J. See 74, p. 602.

FRANCONI(GARTNER). Die Dressurder Kunstpferde. Jahrbuch
fur Pferdezucht, Pferdekenntnis, Pferdehandel usw. auf das
Jahr 1835, Weimar und Ilmenau, 1835, Jahrg. 11, p. 329.

LotseT, B. See 71, p. 130.

HACHET-SOUPLET, P. See 110, p. OI.

KNICKENBERG, F. Der Hund und sein “ Verstand.” Céthen
(Anhalt), P. Schettlers Erben, 1905, pp. 129 f.

Lane, R. Geheimnisse zur kiinstlichen Abrichtung der Hunde,
revised edition. Augsburg and Leipsic, A. Baumer, pp. 46 f.

FRANCONI (GARTNER). See 114, pp. 326 f.

TENNECKER, S. v. Erinnerungen aus meinem Leben. Altona,
I. F. Hammerich, 1838, Vol. 1, pp. 21 f. (The name of the
author is erroneously given on the title page as F. v, Ten-
necker.)

LotseEt, B. See 71, p. 132.

D—. Uber die Abrichtung der kleinen Kunstpferde zu dem
Zahlen mit dem Fusse, Kopfschiitteln und dgl. Zeitung fiir
die Pferdezucht, den Pferdehandel, die Pferdekenntnis usw.
Tiibingen, 1804, Vol. 4, p. 51.

Lane, R. See 118, pp. 52 f.

Burron, CTE DE, et L. DAUBENTON. Histoire naturelle, géné-
rale et particuli¢re. Paris, Imprimerie royale, 1753, Vol. 4

p. 169.

Angell’s Text-book of General Psychology.
New Edition. By James RowLanp ANGELL, Professor and
Head of the Department of Psychology in the University
of Chicago. Fourth Edition, Revised and Enlarged.
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The fourth edition contains a large amount of new material, chiefly
empiricalin character. To offset this addition, many of the more strictly
theoretical discussions have been condensed. The old material has been
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CHARLES H. JUDD, University of Chicago:-—I regard it as a most
excellent text. Its clear and thoroly interesting style will, I am
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pact. Indeed it is a capital presentation of modern psychology.

Seashore’s Elementary Experiments in Psychology.
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A supplement to a regular text-book in elementary psychology. (It
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Jones’s Logic, Inductive and Deductive.
By Apam L. Jonzs, Professor in Columbia University.
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The aim of this text-book is to present, in as concrete a form as is
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Jastrow’s Psychology of Stereoscopic Vision.
By JoszrH Jastrow, Professor in the University of W‘s-
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tary Courses published under each topic, see the publishers’
Educational Catalog.

HENRY HOLT & CO. 3te'wabast Ave. Chicago

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