152 



THE SOCIAL LIFE OF ANIMALS 



roach ability. Approximately one-third of the insects 

 tested never learned to stay on the maze; whenever 

 they were placed on it they proceeded immediately to 

 run off into the underlying water. Of the two-thirds 



n 



16 

 15 

 14 

 13 

 12 

 U 



9- 



8- 



isoIa."tecL * 

 paired 

 J roup of 3 



\ 



I 



15 

 Trials 



— r- 

 20 



25 



Fig. 27. Isolated cockroaches make fewer errors on 

 the maze than the same animals paired, and still fewer 

 than if three are being trained together. 



