270 Journal of Comparative Neurology and Psychology. 



3. Curves of learning for tlie sexes indicate that the female makes 

 more mistakes early in the training tests than does the male, but 

 that this condition soon gives place to greater accuracy of choice on 

 the part of the female. 



4. Initial preference for the white or the black box does not 

 seem to be a very important determinant of the rate of habit-forma- 

 tion. 



5. Tests of sensitiveness indicate that the male dancer is some- 

 what more sensitive to electric stimuli than the female. There 

 are no evidences of changes in sensitiveness with change in age. 



C. The strcng-th of the electric stimulus which is used as an 

 incentive for habit-formation is extremely important as a determi- 

 nant of rate of habit-formation. For a given animal and condition 

 of visual discrimination there is a certain strength of stimulus 

 which is most favorable for the acquisition of the habit (the optimal 

 stimulus), 



7. It is extremely important that experimenters discover the 

 optimal stimulus for habit-formation. 



8. For the dancer the following law appears to hold in connec- 

 tion with the particular habit under consideration and for the 

 electric stimulus. As difficuUness of visual discrimination in- 

 creases ihat strength of electric stimulus which is most favorable 

 (the optimal) to habit- formation approaches the threshold. The 

 easier the habit the stronger that stimulus which most quickly 

 forces its acquisition; the more difficult the habit the weaker the 

 stimulus which most quickly forces its acquisition. 



9. A given diiference in the illumination of the boxes which are 

 to be discriminated cannot be detected with equal ease by old and 

 young dancers. When the difference in illumination is slight the 

 young individuals detect it more readily than the old mice; when 

 the difference is great, the old individuals apparently detect it as 

 readily as do the young mice. 



10. The capacity for "associative memory" is greater, if any- 

 thing, in the dancer of ten months of age than in the one-month 

 individual. This is indicated by certain results of the visual dis- 

 crimination experiments and by the results of labyrinth tests. 



