IMITATION IN MONKEYS 



553 



the circular opcnin.o;. After No. 13 had 

 failed to solve the problem in his prelimi- 

 nary trials, he was allowed to see her pull 

 the string. During the first tests he was 

 confined, as No. 4 had been in the case of 

 the chute. After four tests he still failed 

 when left alone in the cage. He was then 

 put into the experiment cage with No. 5. 

 The two animals were strange to eacli 

 other, and No. 13, being the larger, was 

 inclined to follow 

 No. 5 about the 

 cage, punishing her 

 as opportunity of- 

 fered. Because of 

 this, he was usually 

 near No. 5 when she 

 pulled the string, 

 and often fright- 

 ened her away be- 

 fore she could get 

 the food. After she 

 had been removed. 

 No. 13 repeatedly 

 searched the food- 

 opening, and worked 

 alternately with the 

 three strings nearest 

 it. He seemed to 

 have associated the 

 strings with the get- 

 ting of food. No. 

 5 was put back into 

 the cage, and was 

 billowed to get food 

 again. No. 13 was 

 even more attentive 

 than formerly. Af- 

 ter No. 5 had been 

 removed, No. 13 

 worked more con- 

 tinuously at L and 

 at the strings. He 



now singled out string 2 from the others. 

 He seized the knob at the end of the 

 string in his hands, he pounded it against 

 the board, carried it up the wire, and 

 pounded it against the knobs attached 

 to the other strings. Frequently during 

 this behavior he dropped the string and 

 searched L for food. He had advanced 

 one step in his learning: it was not strings 

 that were associated wnth the getting of 

 food, but a particular string. The only 

 possible explanation for this centering of 

 attention on. .a particular string was that 

 No. 13 was imitating the act of No. 5. 



NO. 13 PULLING THE STRING AND 



GETTING FOOD 



. His tense position indicates the eagerness 

 with which he worked. 



Imitation, liowever, was not yet perfect. 

 No. 13 withdrew up the front of the cage, 

 and, perching upon a brace, sat looking at 

 L and the string. He seemed puzzled. 

 He went to the floor and sat down in 

 front of L, looking intently, but he did 

 not touch the string or the opening. Again 

 he perched on the brace and looked at the 

 string and at L. Again he went to the 

 floor and sat in front of the food-opening. 



Quite deliberately 

 he looked the situa- 

 tion over. Then in 

 the same deliberate 

 manner he looked up 

 to string 2, took 

 hold of the knob in 

 his left hand, and 

 gave a steady and 

 vigorous pull. The 

 food dropped to the 

 bottom of the chute, 

 and his right hand 

 shot into the open- 

 ing and pulled it 

 out. He ate the food, 

 and immediately 

 pulled the string 

 again. Then for fif- 

 teen minutes he sat 

 before L and got 

 food. He never for- 

 got the trick. Such 

 ability to learn by 

 watching the beha- 

 vior of other mon- 

 keys must be of great 

 importance in the 

 normal life of pri- 

 mates, and goes far 

 to account for the 

 high position that 

 they hold in the 

 scale of animal intelligence. 



That the tendency of monkeys to learn 

 by imitation is deep-seated, is shown by 

 the total results of my investigation. No 

 one of the seven experiments failed to 

 yield at least one case of imitation. Four 

 of the experiments yielded imitation, suc- 

 cessful or partly successful for every ani- 

 mal given the full series of tests. The 

 otlier three gave a total of five failures. 

 As a whole, the investigation yielded six- 

 teen cases of successful imitation, three of 

 which were immediate. 



Of the eleven animals used, all but two 



