28 



HARRY H. WYLIE 



These records indicate that it is highly probable that the 

 rats were depending in part at least upon certain movements 

 made by the experimenter rather than upon the sound 

 stimulus which was to serve as the guide in making the 

 choice. 



This complete failure to get any rats, either trained pre- 

 viously with the light or wholly untrained, either with 

 punishment for wrong choice or without punishment, ta 

 learn the positive response to any sound stimulus presented 

 was one of the most surprising results of the experiments. 

 As suggested above the most plausible reason for this 

 failure seems to be that the rats were unable to localize the 

 sound sufficiently well under the conditions of the experi- 

 ment to enable them to utilize the sound in learning the 

 response required. 



However, it would not be correct to say that these animals 

 trained with the sound made no improvement at all. The 

 fact is that all of them actually made improvement during 

 the first 300 trials. To what was this improvement due? 

 To answer that question we need first to know the amount 

 of improvement made. We find that Group III in the first 

 100 trials made 49.8 per cent of correct responses, while in 

 the fourth 100 trials the same group made 61 per cent of 

 correct responses. Group IV in the first 100 trials made 

 51.2 per cent of correct responses, while in the fourth 100 

 trials the same group made 60 per cent of correct responses. 

 Group V in the first 100 trials made 53.6 per cent of correct 

 responses, while in the fourth 100 trials the same group 

 made 65.8 per cent of correct responses. Thus roughly for 

 the three groups the gain amounted to about 10 per cent. 



