314 



K. S. LASHLKY 



No. 6. Female, age unknown ; she had given birth to one 

 litter which she devoured; very tame, accustomed to being 

 handled. Judged from her general behavior, this rat seems to 

 use vision to a greater extent than the others. 



No. 7. Female, age unknown; forms position associations 

 very readily. 



EXPERIMENT 1. DISCRIMINATION OF FORM 



Apparatus: The discrimination box; two standard stimulus 

 plates showing a square and a circle of equal area (56.548 

 sq. cm.). The experiment was conducted in a darkened room. 

 Rats Nos. 1, 2 and 3 were used. Since they showed no prefer- 

 ence for either form, the square was chosen arbitrarily as the 

 positive stimulus. The motive differed for each of the animals. 



No. 1. Food after a correct choice only. 



No. 2. Food after every trial, punishment after an incorrect 

 choice. 



No. 3. Food after correct, punishment after incorrect choice. 



During the first part of this experiment no precautions were 

 taken to eliminate other than visual stimuli to which the rats 

 might learn to react. The noise made in reversing the stimuli 

 and other movements and sounds made by the experimenter 

 were thus available to the animals as indices of the passage to 

 be chosen. 



Table I, giving the percentage of error in each 100 trials, 

 shows the record made by the animals in 1000 trials. The per- 

 centage of error was never small enough to justify the conclusion 

 that the animals were reacting to the difference in the visual 

 stimuli. The occasional low percentages are to be explained by the 

 appearance of reactions to sound, or to other accidental stimuli. 



TABLE I 

 Discrimination Between Square and Circle of Equal Area. Per- 

 centage of Error in Each Consecutive Hundred Trials 



