i62 



THE SOCIAL LIFE OF ANIMALS 



groups of goldfish learned to move forward and se- 

 cure food more rapidly than the same number of 

 isolated fish. 



The conditions of the experiments allow certain 





TRIAL 



Fig. 33. Isolated goldfish learn the problem set for 

 them less rapidly, and unlearn it more readily. (From 

 Welty.) 



types of analyses to be made. One of these is to test 

 the tenacity with which the newly acquired habit 

 will be retained. A set of fish was trained as usual 

 (Figure 33). After ten days, when the grouped fish 

 had been letter-perfect for four days, although the 

 isolated goldfish were still taking some three min- 

 utes per trial, the experiment was changed; when- 



