IMITA'J JON IN MONKEYS 



547 



JACK. CEBUS LUNATUS, THREE YEARS OLD 



He solved three of the problems alone ; the other 

 four he learned by imitation. 



chute. For eleven days she repeated this 

 behavior, during the later daj's scolding 

 much less and examining the cage more. 

 Every corner and crack on the floor, sides, 

 or top of the cage that could be reached 

 was explored by Jill's curious nose and 

 fingers. Yet in all the fifteen half-hours, 

 on as many different days, Jill paid no 

 attention to the chute. So impossible did 

 it seem that in her vigorous activity she 

 should leap all about the cage, almost di- 

 rectly past the chute at times, and never 

 once jump to it, that on January 23 and 

 January 24 I called in other observers to 

 verify my reports. On these days her be- 

 havior was the same, and we were all 

 agreed that it was not probable that Jill 

 would learn of her own accord. We were 

 also agreed that the conditions were excel- 

 lent to test whether Jill could learn from 

 Jack. 



Accordingly, on January 25, I placed 

 the two animals in the cage together. Jack 

 was quick at his work, and with great 

 dexterity he set the copy for Jill seven 

 times within a few minutes. Jill saw the 

 entire performance twice and in part at 

 least four other times. Jack was then re- 

 moved from the cage, and Jill was left 

 alone for thirty minutes. I quote here 

 from the notes for the day: "After a few 

 minutes of climbing about, Jill looked up 

 at the chute from the floor ; she stood on 

 her feet, lifted her body and face upward, 

 climbed the side of the cage as if she were 

 making straight for the side of the chute, 

 but she did not jump across. During the 

 remainder of the interval there was no 



evidence that Jill was influenced by what 

 she had seen." 



Jack was again placed in the cage and 

 allowed to operate the mechanism. Each 

 time Jill got food, and at times took all of 

 it. Twice again she saw the entire per- 

 formance and four times saw it in part. 

 Jack was then removed. During the 

 thirty minutes that followed there war, 

 not the slightest thing to indicate that 

 the performance of Jack had influenced 



These imitation tests were repeated on 

 sixteen different days. Jack operated the 

 device a total of two hundred and fifty- 

 three times, two hundred and four of 

 which Jill saw entire. On no day did she 

 see the entire performance fewer than 

 three times nor oftener than twenty times, 

 and after each day's observation she was 

 given thirty minutes. The nearest ap- 

 proach to imitation was on February 6. 

 After Jack was taken out, she climbed the 

 cage near the chute. Holding with feet, 

 tail, and one hand, she threw her head and 

 body out from the cage, extending the free 

 hand as if reaching for the chute. She did 

 not jump. Poor stupid Jill would appa- 

 rently have starved to death with a load 

 of bananas on top of the trap-door, and 



JACK GETTING FOOD IN THE CHUTE 

 EXPERIMENT 



LXXVIIl-61 



