94 



K. S. LASHLEY 



The formation of a visual habit 



Methods. Seven normal and four operated animals were 

 trained in a habit of brightness discrimination and their rates of 

 learning compared. The apparatus used was a simple Yerkes' 

 discrimination box (previously used and figured by Dodson, '17) 

 offering the choice of an illuminated and a dark alley, food being 

 given with the light and no food with darkness. If the animal 



TABLES 



The average percentage of errors made by normal animals and by animals after 

 injury to the frontal pole of the cerebrum during successive days' practice inform- 

 ing a habit of visual discrimination. The averages are based on seven normal and 

 three operated animals trained under uniform conditions with ten trials per day 



PER CENT ERROR 



entered the darkened alley an error was recorded. Training 

 was continued with 10 trials per day until 20 successive trials 

 were made without error. Records of the animals follow. 



Normal animals. The seven normal animals required an av- 

 erage of 106.6 trials for learning, not including the final 20 trials 

 without error, with a range from 60 to 130. Details of their 

 records will be given in another paper. Their daily averages 

 are given in table 5. 



