HISTORICAL AND CRITICAL DISCUSSION OF IDEATIONAL BEHAVIOR IN MONKEYS AND
APES
It is my purpose in this section to indicate the relations of my work on
monkeys and apes to that of other investigators. Although throughout the
report I have used freely the psychological terms idea and ideation, it
has been my aim to describe the behavior of my animals rather than to
interpret it or speculate concerning its accompaniments. Certain acts I
have designated as ideational simply because they seemed to exhibit the
essential features of what we call ideational behavior in man. Further
study may, and probably will, modify my opinion concerning this matter.
It is of prime importance to analyze ideational behavior so that it may
be accurately described and satisfactorily defined in terms of its
distinguishing characteristics. I had hoped to be able to present a
tentative analysis in this report, but the results of my efforts are so
unsatisfactory that I do not feel justified in publishing them.
The terms idea and ideation have been used to designate contents of
consciousness which are primarily representative. Nowhere have I
attempted to indicate different types or grades of ideational behavior
and nowhere have I found it necessary to emphasize differences between
image and idea. In general, the acts which I have called ideational have
been highly adaptive, and the learning processes in connection with
which they have appeared have differed strikingly from those of the
selective sort in their abruptness of appearance.
Extremely interesting and valuable definitions of ideation and
discussions of the characteristics of different sorts of ideas in the
light of original observations on monkeys have been presented by
Thorndike (1901, pp. 1, 2; 1911, p. 174); Kinnaman (1902, p. 200); and
Hobhouse (1915, p. 270). As these authors have contributed importantly
to our knowledge of the behavior of monkeys, their discussions of the
meaning of terms are especially valuable. Serviceable definitions are to
be found, also, in Romanes (1900), Morgan (1906), Washburn (1908), and
Holmes (1911).
_Evidences of Ideation in Monkeys_
Aside from anecdotal and traveller's notes on the behavior of monkeys
and apes we have only a scanty literature. In fact, the really excellent
articles on the behavior and mental life of these animals may be counted
on one's fingers; and not more than half of these are experimental
studies. I shall, in this brief historical sketch, neglect entirely the
anecdotal literature, since my own work is primarily experimental, and
since its results should naturally be compared with those of other
experimenters.
Thorndike (1901), the American pioneer in the application of the
experimental method to the study of mind in animals, published the first
notable paper on the psychology of monkeys. His results force the
conclusion that "free ideas" seldom appear in the monkey mind and have a
relatively small part in behavior. That the species of Cebus which he
observed exhibits various forms of ideation he is willing to admit. But
he insists that it is of surprisingly little importance in comparison
with what the general behavior of monkeys as known in captivity and as
described by the anecdotal writers have led us to expect. It is
important to note, however, that Thorndike's observations were limited
to Cebus monkeys which, as contrasted with various old world types, are
now considered of relatively low intelligence.
In many respects the most thoroughgoing and workmanlike experimental
study of monkeys is that of Kinnaman (1902), who has reported on the
study of various forms of response in _P. rhesus_. He presents valuable
data concerning the learning processes, sensory discrimination, reaction
to number, and to tests of imitation. His results indicate a higher
level of intelligence than that discovered by Thorndike, but this is
almost certainly due to difference in the species observed. Kinnaman
goes so far as to say "We have found evidence, also, of general notions
and reasoning, both of low order" (p. 211).
The contribution of Hobhouse (1915) to our knowledge of the mental life
of monkeys, although in a measure experimental, is based upon relatively
few and unsystematic observations as contrasted with those of Thorndike
and Kinnaman. It appears, however, that Hobhouse's experiments were
admirably planned to test the ideational capacity of his subjects, and
one can not find a more stimulating discussion of ideation than that
contained in his "Mind in Evolution." The results of his tests made with
a _P. rhesus_ monkey are similar to those of Kinnaman, for almost all of
them indicate the presence and importance of ideas.
Watson (1908) in tests of the imitative ability of _P. rhesus_ saw
relatively little evidence of other than extremely simple forms of
ideation. But in contrast with his results, those obtained by Haggerty
(1909), in a much more extended investigation in which several species
of monkey were used, obtained more numerous and convincing evidences of
ideation in imitative behavior. Although this author wholly avoids the
use of psychological terms, seeking to limit himself to a strictly
objective presentation of results, it is clear from an unpublished
manuscript (thesis for the Doctorate of Philosophy, deposited in the
Library of Harvard University) that he would attribute to monkeys simple
forms of ideational experience.
Witmer (1910) reports, in confirmation of Haggerty's results,
intelligently imitative behavior in _P. irus_.
The work of Shepherd (1910) agrees closely, so far as evidences of
ideation are concerned, with that of Thorndike. He obviously strives for
conservatism in his statements concerning the adaptive intelligence of
his monkeys, all of which belonged to the species _P. rhesus_. At one
point he definitely states that they exhibit ideas of a low order, or
something which corresponds to them. Satisfactory evidences of reasoning
he failed to obtain.
Franz's (1907, 1911) studies of monkeys, unlike those mentioned above,
have for their chief motive not the accurate description of various
features of behavior but instead knowledge of the functions of various
portions of the brain. His results, therefore, although extremely
interesting and of obvious value to the comparative psychologist, throw
no special light upon the problem of ideation.
The investigation by Hamilton (1911) of reactive tendencies in _P.
rhesus_ and _irus_ yielded preeminently important data concerning
complex behavior. For the ingenious quadruple-choice method devised by
this observer showed that mature monkeys exhibit fairly adequate types
of response. As Hamilton's interest centered in behavior, he did not
discuss ideation, but this does not prevent the comparison of his data
with those of the present report, and the agreement of his findings with
my own is obvious.
My work contrasts sharply with that briefly mentioned above in that I
applied systematically and over a period of several months an
experimental method suited to reveal problem solving ability.
Previously, the so-called problem or puzzle-box method had been used as
a means of testing for the presence of ideas. For this I substituted the
multiple-choice method. One of the chief advantages of this new method
is the possibility of obtaining curves of learning for the solution or
attempted solution of relational problems of varying difficultness. I am
confident that these curves of learning will prove far more valuable
than such data as are yielded by the puzzle-box method.
The Pithecus monkeys, which I studied intensively, yielded relatively
abundant evidences of ideation, but with Thorndike I must agree that of
"free ideas" there is scanty evidence; or rather, I should prefer to
say, that although ideas seem to be in play frequently, they are rather
concrete and definitely attached than "free." Neither in my sustained
multiple-choice experiments nor from my supplementary tests did I obtain
convincing indications of reasoning. What Hobhouse has called articulate
ideas, I believe to appear infrequently in these animals. But on the
whole, I believe that the general conclusions of previous experimental
observers have done no injustice to the ideational ability of monkeys.
It is clearly important, however, that we always should take into
account the species of animal observed, for unquestionably there are
extreme differences in mental development among the monkeys.
As I view my results in the light of their relations to earlier work, I
am strongly impressed with the importance of the use of improved methods
for the study of complex behavior. The delayed reaction method of
Hunter, the quadruple-choice method of Hamilton, and my multiple-choice
method offer new and promising approaches to forms of activity which
thus far have been only superficially observed.
The ability exhibited by Skirrl to try a method out and then to abandon
it suddenly is characteristic of animals high in intelligence. Most of
the problems which I presented to my animals would be rated as difficult
by psychologists, for as a rule they involved definite relations and
demanded on the part of the subject both perception of a particular
relation and the ability to remember or re-present it on occasion.
I was greatly surprised by the slow progress of the monkeys toward the
solution of these problems. It had been my supposition that they would
solve them more quickly than any lower type of mammal, but as a matter
of fact they succeeded less well than did pigs. Their behavior
throughout the work proved that of far greater significance for the
experimenter than the solution of a problem is definite knowledge of the
modes of behavior exhibited from moment to moment, or day to day. This
is true especially of those incidental or accidental modes of response
which so frequently appeared in connection with my work that I came to
look upon them, the surprises of each day, as my chief means of insight.
_Evidences of Ideation in Apes_
Reliable literature of any sort concerning the behavior and mental life
of the anthropoid apes is difficult to find, and still more rare are
reports concerning experimental studies of these animals. There are, it
is true, a few articles descriptive of tests of mental ability, but even
these are scarcely deserving of being classed as satisfactory
experimental studies of the psychology of the ape. I have the
satisfaction of being able to present in the present report the first
systematic experimental study of any feature of the behavior of an
anthropoid ape.
Among the most interesting and valuable of the descriptions which may be
classed among accounts of tests of mental ability is Hobhouse's (1915)
study of the chimpanzee. The subject was an untrained animal, so far as
stated, of somewhat unsatisfactory condition because of timidity.
Nevertheless, Hobhouse was able to obtain from him numerous and
interesting responses to novel situations, some of which may be safely
accepted as evidences of ideation of a fairly high order.
Similar in method and result to the work of Hobhouse is that of Haggerty
(unpublished thesis for the Doctorate of Philosophy, deposited in the
Library of Harvard University). Haggerty's tests of the ability of young
orang utans and chimpanzees to solve simple problems and to use tools in
various ways yielded results which contrast most strikingly with those
obtained in his experimental study of the imitative tendency in monkeys.
His observations, had he committed himself to anything approaching
interpretation, doubtless would have led him to conclusions concerning
the ideational life of these animals very similar to those of Hobhouse.
Koehler, working in the Canary Islands, has, according to information
which I have received from him by letter, made certain experiments with
orang utans and chimpanzees similar to those of Hobhouse and Haggerty.
His results I am unable to report as I have scanty information
concerning them. They are, presumably, as yet unpublished.
In his laboratory at Montecito, California, Hamilton has from time to
time kept anthropoid apes, but without special effort to investigate
their ideational behavior. He has most interesting and valuable data
concerning certain habits and instincts, all as yet unpublished.
To a congress of psychologists Pfungst (1912) briefly reported on work
with anthropoid apes in certain of the German zoölogical gardens. His
preliminary paper does not enable one to make definite statements
concerning either his methods or such results as he may have obtained
concerning ideational behavior. So far as I know, he has not as yet
published further concerning his investigation.
Möbius (1867) has described interesting observations concerning the
mental life of the chimpanzee. But this, like all of the work previously
mentioned, is rather in the nature of casual testing than thoroughgoing,
systematic, and analytic study.
In addition to the above reports, there are a few concerning the
behavior of apes which have been especially trained for purposes of
exhibition. Most interesting of these is that of Witmer (1909), who
studied in exhibitions and in his own laboratory the behavior of the
chimpanzee Peter. The varied forms of intelligently adaptive behavior
exhibited by this ape convinced Witmer of ideational experience and even
of an approach to reasoning. In his brief report he expresses especial
interest in the possibility of educating this "genius among apes" to the
use of language.
A chimpanzee named Consul was observed several years ago by Hirschlaff
(1905), and his tricks were interestingly described from the pedagogical
standpoint.
Similar in character is Shepherd's (1915) brief description of the stage
behavior of Peter and Consul, both chimpanzees. It is impossible to
determine from the account whether these animals are the same as were
observed by both Witmer and Hirschlaff. As no reference is made in
Shepherd's paper to other descriptions of the behavior of these animals
and as he adds nothing to what had already been presented, the reader
obtains no additional light on ideation.
I have mentioned only samples of the articles on trained anthropoids.
All are necessarily descriptions of the behavior of individuals who had
been trained not for psychological purposes but for the vaudeville
stage, and although such observations unquestionably have certain value
for comparative psychology, it is well known that unless an observer
knows the history of an act, he is not able to evaluate it in terms of
intelligence and is especially prone to overestimate its value as
evidence of ideation.
There remain studies of the apes, dealing primarily with behavior and
mental characteristics, which are slightly if at all experimental and
deserve to be ranked as naturalistic accounts. Such is, for example, the
book of Sokolowski (1908), in which attention is given to the
characteristics of young as well as fairly mature specimens of the
gorilla, chimpanzee and orang utan.
The various publications of Garner (1892, 1896, 1900) deal especially
with the language habits of monkeys and apes, but observations bearing
on ideation are reported.
Wallace (1869) describes certain features of the behavior of an infant
orang utan whose mother he shot in Borneo. He also reports observations
concerning the behavior of adult orang utans, many specimens of which
were shot by him during his travels.
Early in the last century, Cuvier (1810) interested himself in studies
of the intellectual characteristics of the orang utan, and his data,
taken with those of Wallace, Sokolowski, and others similarly interested
in the natural history of mind, give one a valuable glimpse of the life
of the anthropoid ape.
Finally, the data brought together by Brehm (1864, 1875, 1888) in his
famous Tierleben; by Darwin (1859, 1871) in "The Origin of Species," and
other works, by Romanes (1900), especially in his books on mental
evolution, by C. Lloyd Morgan (1906) in his several works on comparative
psychology, and by Holmes (1911) in his discussion of the evolution of
intelligence, contribute not unimportantly to our all too meagre
knowledge of the mental life of the anthropoid apes.
My own results, viewed in the light of what one may learn from the
literature, stand out as unique because of the method of research. Never
before, so far as I have been able to learn, has any ape been subjected
to observation under systematically controlled conditions for so long a
period as six months. Moreover, my multiple-choice method has the merit
of having yielded the first curve of learning for an anthropoid ape.
This fact is especially interesting when one considers the nature of the
particular curve. For so far as one may say by comparing it with the
curves for various learning processes exhibited by other mammals, it is
indicative of ideation of a high order, and possibly of reasoning. I do
not wish to exaggerate the importance of my results, for as contrasted
with what might be obtained by further study, and with what must be
obtained if we are adequately to describe the mind of the orang utan,
they are meager indeed.
Especially noteworthy, as evidences of ideation, in the results yielded
by the multiple-choice method are (1) the use by the orang utan of
several different methods in connection with each problem; (2) the
suddenness of transition from method to method; (3) the final and
perfect solution of problem I without diminution of the initial errors;
(4) the dissociation of the act of turning in a circle from that of
standing in front of a particular box.
To these features of behavior others of minor importance might be added.
But as they have been sufficiently emphasized in the foregoing detailed
descriptions, I need only repeat my conclusion, from the summation of
evidence, that this young orang utan exhibited numerous free ideas and
simple thought processes in connection with the multiple-choice
experiment. His ultimate failure to solve the second problem is
peculiarly interesting, although in the light of other features of his
behavior by no means indicative of inferior intelligence.
The various supplementary experimental tests which I employed are in no
wise importantly distinguished from those used by other observers. The
box stacking experiment has, according to my private information, been
used by Koehler. It is obviously important that such tests be applied in
the same manner to individuals not only of the different genera of
anthropoid apes, but of different ages, sex, and condition of training.
The box stacking experiment, although it yielded complete success only
as a result of suggestion on my part, proved far more interesting during
its progress than any other portion of my work. In connection with it,
the orang utan exhibited surprisingly diverse and numerous efforts to
meet the demands of the situation. It is fair to characterize him as
inventive, for of the several possible ways of obtaining the banana
which were evident to the experimenter, the ape voluntarily used all but
two or three, and one of these he subsequently used on the basis of
imitation.
Had Julius been physically and mentally mature, my results would
undoubtedly have been much more impressively indicative of ideas, but
even as matters stand, the survey of my experimental records and
supplementary notes force me to conclude that as contrasted with the
monkeys and other mammals, the orang utan is capable of expressing free
ideas in considerable number and of using them in ways highly indicative
of thought processes, possibly even of the rational order. But
contrasted with that of man the ideational life of the orang utan seems
poverty stricken. Certainly in this respect Julius was not above the
level of the normal three-year-old child.
In common with other observers, I have had the experience of being
profoundly impressed by the versatility of the ape, and however much I
might desire to disprove the presence of free ideas and simple reasoning
processes in the orang utan, I should feel bound to accept many of the
results of my tests as evidences of such experience.
I have attempted to indicate briefly the historical setting of my
investigation. I propose, now, in the concluding section, to look
forward from this initial research and to indicate as well as I may in a
few words the possibilities of results important for mankind from the
thorough study of the monkeys and anthropoid apes.