The Mental Life of Monkeys and Apes: A Study of Ideational Behavior

erms 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 ide

defined in terms of its distinguishing characteristics. I had hoped to be able to present a tentative analysis in

des 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 h

ented 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 mo

of Ideatio

nd 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, negl

ave 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

aluable 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 Thorn

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 ideati

igation 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 strictl

ion of Haggerty's results, intellig

atism in his statements concerning the adaptive intelligence of his monkeys, all of which belonged to the species P. rhesus. At one point he defini

various features of behavior but instead knowledge of the functions of various portions of the brain. His results, therefore, altho

adruple-choice method devised by this observer showed that mature monkeys exhibit fairly adequate types of response. As Hamilton's interest centered in behavior, he di

m 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

itely 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

ved methods for the study of complex behavior. The delayed reaction method of Hunter, the quadruple-choice method of Hamilton, and my

of the problems which I presented to my animals would be rated as difficult by psychologists, for as a rule they involved definite relatio

d 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,

of Ideat

se 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 th

himpanzee. The subject was an untrained animal, so far as stated, of somewhat unsatisfactory condition because of timidity. Nevertheless, Hobhouse was able to

g 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 monk

made certain experiments with orang utans and chimpanzees similar to those of Hobhouse and Haggerty. His resul

apes, but without special effort to investigate their ideational behavior. He has most in

rdens. His preliminary paper does not enable one to make definite statements concerning either his methods or such results as he m

f the chimpanzee. But this, like all of the work previously mentioned, is rather

909), 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

s ago by Hirschlaff (1905), and his tricks were int

om 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 de

logical purposes but for the vaudeville stage, and although such observations unquestionably have certain value for comparative psychology, it is well known that unless

perimental and deserve to be ranked as naturalistic accounts. Such is, for example, the book of Sokolowski (1908), in which a

eal especially with the language habits of monkeys and

hose mother he shot in Borneo. He also reports observations concerning the behavior

tics of the orang utan, and his data, taken with those of Wallace, Sokolowski, and others similarly in

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 (191

, 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 mamm

ferent methods in connection with each problem; (2) the suddenness of transition from method to method; (3) the final and perfect solution of problem

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

e box stacking experiment has, according to my private information, been used by Koehler. It is obviously important that such tests be applie

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 severa

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, po

he ape, and however much I might desire to disprove the presence of free ideas and simple reasoning processes i

luding section, to look forward from this initial research and to indicate as well as I may in a few words t