222 'Journal of Comparative Neurology and Psychology. 



Complexity of Associations. — It was my purpose to compare the 

 complexity of the associations a raccoon is able to form with those 

 formed by monkeys. I therefore combined new fastenings with 

 those aheady learned until in Box 13 I came very near the limit 

 of their abilities. In Box 21, I also tested the animals' ability to 

 operate three hitherto untried fastenings and I changed the plan 

 from coming out to be fed to going into the box for that purpose. 

 The animals all succeeded in learning to work seven fastenings : 

 namely, two buttons, two bolts lifted by a pull on each of two loops 

 hung in different parts of a large box, one thumb-latch, one bolt 

 raised by the animal's mounting a platform and a horizontal hook 

 placed at the left side of the door. The thumb-latch had to be 

 worked last. The raccoons thus learned a combination of seven 

 latches. The rhesus monkey did the same, but no doubt the rac- 

 coons were given more trials. The average time required for the 

 first trial in boxes of two to seven fastenings, inclusive, is 65 sec- 

 onds, for the second trial, 44 seconds. Kinnaman^ gives 25.5 as 

 the average of first trials in similar combinations and 16.5 as the 

 average of second trials. Thus, for both raccoons and monkeys 

 working with groups of fastenmgs, the tmie required ior the sec- 

 ond success is but two-thirds the time for the first. The anoma- 

 lous case of raccoon No. 3 in Box 13 in which he required only 

 thirty-one seconds for the first trial, and seven hundred forty-six 

 for the second, has not been included in the average, for to include 

 it would have been to let one peculiar case be equal to eighteen 

 ordinary cases. His third trial is two hundred ninety-six seconds. 

 This case of No. 3 in Box 13 is an example of the fact already 

 mentioned that a raccoon may operate a mechanism quickly once 

 or twice before his actual learning begins. 



In boxes of two to seven fastenings there is almost no tendency 

 to follow a routine order in undoing them. Occasionally a defi- 

 nite order may appear one day and another the next in the same 

 box, but neither is followed very closely. Several hundred experi- 

 ences in Boxes 12 and 13 failed to establish a definite order. The 

 raccoon often seems to begin with the first fastening which 

 attracts his attention. With more than four fastenings each ani- 

 mal showed a tendency to forget a certain one of them, for exam- 

 ple, one button or one loop throughout the day's training, or per- 

 haps for two successive days. The case seems not unlike that 



*Amer. Jour, of P:ychol., vol. 13, p. 118. 



