GROUP BEHAVIOR 



153 



that did learn to remain on the maze, a half, or an- 

 other third of all those tested, did not show improve- 

 ment in speed of reaching the bottle, after repeated 



10 



15 

 Trials 



20 



25 



Fig. 28. They also take less time. 



trials. Thus only one-third of the cockroaches we 

 tested showed improvement with experience, and, 

 as I said before, they forgot overnight all that they 

 learned during the day. 



As shown in the summarizing graphs (Figures 27 

 and 28), isolated cockroaches made fewer errors per 

 trial throughout the whole training period. They 



