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THE CENTURY MAGAZINE 



exhibited imitative behavior. Seven of 

 them Vv'ere successful in each experiment 

 in which they were used. 



Jack vied with No. 5, a female Cebus, 

 for the best record, but lost because he 

 failed to learn the string experiment alone, 

 and time did not permit his being given 

 the imitation tests. No. 5 solved three of 

 the problems alone or with slight help 

 from me, and learned the other four by 

 imitation. Four other animals imitated 

 at evTry opportimity, but they cannot be 

 compared w^ith the two above because they 

 were given .fewer tests. 



The monkeys exhibited five levels of 

 imitative behavior, which may be summar- 

 ized as follows: (a) simple arrest of at- 

 tention; (b) following; (c) reaction to 

 locality; (d) reaction to an object; (e) 

 exact repetition in detail of an act wit- 

 nessed. 



By the "simple arrest of attention" I 

 mean that the monkeys watch one another. 

 One animal walks across the floor of the 

 cage or climbs a pole, and another animal 

 looks in its direction. That monkeys man- 

 ifest this sort of reaction requires no ex- 

 tended experimentation to prove. Every 

 moving object, and much more every mov- 

 ing monkey, catches their attention. 



A level of social response more ad- 

 vanced than mere looking is followuiq. 

 Closely akin to this is behavior of the sort 

 in which one animal performs an act, and 

 another animal at once repeats the act. It 

 requires but little observation of monkeys 

 to show that the tendency to imitate in 

 this way is present. Not one of the species 

 which I have studied failed to follow, and 

 there were cases in which the monkeys 

 repeated the act of another when it was 

 unaccompanied by any profitable result. 



More complicated than looking or fol- 

 lowing is what I choose to call reaction to 

 locality. It often happened that one mon- 

 key would go to a certain part of the cage, 

 get food, and go awav. Another monkev 

 which had observed this behavior would 

 then go to that portion of the cage and 

 hunt about, but would not attack the but- 

 ton, string, or plug necessary to get the 

 food. 



It denotes a level of behavior distinctly 

 higher when the observing monkey not 

 only goes to a certain locality, but attacks 

 a particular object in that locality. In the 

 rope experiment, No. 4 climbed the rope 



after she had seen Jack get food. She 

 looked all about that portion of the top of 

 the cage. She smelled about the edges of 

 the food-door. She put her hand on the 

 door, and rubbed it up and down. She 

 did not, however, push on the door to 

 open it. Here the particular object was 

 singled out, but the exact movement was 

 not repeated. 



Of a distinctly higher grade would seem 

 to be the behavior of No. 3 in the button 

 experiment. That animal had failed dur- 

 ing his preliminary trials to move the 

 button or to be interested in it. After 

 seeing another monkey push the button in 

 the imitation test, he went to it, and, seiz- 

 ing it in his hand, gave a vigorous push to 

 the right, just as he had seen the other 

 m.onkey do. Here we have exact repeti- 

 tion in detail of the act witnessed. 



In conclusion, let me indicate in what 

 direction such investigations lead. The 

 experimental movement which has charac- 

 terized the last quarter-century of human 

 psychology has, within ten years, been rig- 

 idly applied to the study of the psychic life 

 of animals. The animal mind, hitherto a 

 region of myth and a field for human 

 fancy, has been subjected to severe experi- 

 mental conditions, with a view to deter- 

 mine accurately what it involves. Studies 

 have been made on the senses, on memory, 

 on the power of association, on the pres- 

 ence of ideas, and on the abilitv to learn 

 by imitation. Activities in the field have be- 

 come so nurnerous that animal psychology 

 may fairly be termed a current scientific 

 movement, a movement in which American 

 universities are holding a foremost place. 



As yet, to be sure, the amount of estab- 

 lished data is not large, and the data con- 

 cerning almost any single animal or any 

 single problem is very meager. In view of 

 this scantiness of established facts, most 

 investigators in the field are somewhat 

 chary about hazarding opinions as to what 

 are the psychic accompaniments of an\ 

 kind of animal behavior. I feel this hesi- 

 tancy about making any psychic interpre- 

 tation of the behavior w^hich I have 

 witnessed. I am content at present with 

 the more modest task of describing the 

 behavior of the monkeys, of indicating the 

 levels of perfection of imitative behavior 

 which they exhibited, and of setting forth 

 the conditions imder which imitation took 

 place. 



