Yerkes and Dodson, Habit Formation. 



471 



than did those which were trained with the medium strength of 

 stimulus. 



The general result of this preliminary set of experiments with 

 three roughly measured strengths of stimulation was to indicate 

 that neither a weak nor a strong electrical stimulus is as favorable 

 to the acquisition of the white-black habit as is a medium stimulus. 



TABLE 5. 

 The results of the experiments of set I, stimulus strong (500 i 50 units). 



Contrary to our expectations, this set of experiments did not prove 

 that the rate of habit-formation increases with increase in the 

 strength of the electric stimulus up to the point at which the shock 

 becomes positively injurious. Instead an intermediate range of 

 intensity of stimulation proved to be most favorable to the 

 acquisition of a habit under the conditions of visual discrimination 

 of this set of experiments. 



