268 JOHN D. DODSON , 



COMPARISON WITH EARLIER RESULTS 



Do the above results agree with the results found in previous 

 experiments on the relative values of different strengths of stimuli 

 in habit formation? Were one to examine the results given by 

 the different experiments without taking into consideration the 

 nature of the subjects used he would conclude that the results 

 are almost diametrically opposed. But when one takes into con- 

 sideration the differences in the natures of the animals it seems 

 that the results point to a common principle. As everyone who 

 is acquainted with the dancing mouse knows, this animal is not 

 especially sensitive to its environment. It dances in the presence 

 of danger with the same indifference to its environment that it 

 does in its cage. It enters an electric box where it may receive a 

 strong shock almost as readily as it does a box where there is 

 no form of punishment. Ordinary changes in its environment 

 affect its behavior very little. On the other hand the rat is 

 extremely sensitive to its environment. The slightest movement 

 in its presence may call forth the native tendency of flight with 

 the suddenness of a simple reflex. 'Subjects trained with electric 

 shock had to be forced through the door between the nest box 

 and the entrance chamber, and here in the presence of the electric 

 boxes the primary motive for choice seemed to be to escape from 

 the situation. If, as all these experiments indicate, there is a 

 point of interference as the strength of stimulus is increased this 

 point should be reached much sooner with the rat than the dancer. 

 And the interference due to excitement will appear much earlier 

 in the series of difficultness with the rat than with the dancer. 

 Thus the most favorable strength of stimulus for habit formation 

 in the rat should be weaker than the most favorable strength of 

 stimulus for the dancer and interference due to excitation should 

 be more noticeable in the rat than in the dancer. 



SUMMARY OF FACTS TO BE EXPLAINED 



The above results present certain obvious facts which need 

 interpretation. Why should rats of similar heredity and en- 

 vironment perfect a like habit in so widely different lengths of 





