THE INTERFERENCE OF VISUAL HABITS 171 



shaded by one thickness of ordinary writing paper as men- 

 tioned above. 



Table 1 shows the number of trials required by the rats in 

 establishing the association. The standard of learning was as 

 follows: Each of the last four series of 10 trials must show at 

 least 8 correct reactions, but the average percentage of correct 

 reactions for the four series must not be less than 87§%. The 

 trials in table 1 include all given each rat up to the 40 made at 

 the standard percentage. 



TABLE 1 



Learning Habit No. 1 



Rats Trials 



A comparison of table 1 with similar data obtained by Dr. 

 Hunter in his experiments on the acquisition of auditory habits 2 

 is of value in showing a greater ease in the formation of visual 

 habits by the white rat. My rats ranged between 60 and 300 

 trials with an average of 152. Dr. Hunter's rats, — from the 

 same stock, working in the same apparatus on the same problem, 

 but using sound as a stimulus, — ranged between 210 and 710 

 trials with an average of 423. This is a matter of great import- 

 ance inasmuch as the explanation would appear to lie chiefly, 

 if not wholly, in the different sensory channels involved. I call 

 to mind no prior demonstration of this fact. Extended study, 

 which would go far beyond this preliminary work, would un- 

 doubtedly reveal important differences in vision and hearing so 

 far as the daily life of the rat is concerned. 



As each rat learned the association, control series were intro- 

 duced as follows : 



1. No light used; no punishment. Reaction considered 



right if it fits the series. 



2. An 8 c. p. mazda substituted for the standard light. 



Punishment used. 



2 Op. cit., table 1. 



