334 Jouriin/ of Comparative Neurology and Psychology. 



a distinctive odor, since the animal not only looked at them, but 

 sniffed them carefully before reacting. It is to be remembered 

 that so long as distinctive stimuli were afforded, and so long as the 

 sign boards gave the same stimuli as their appropriate pedal cards, 

 the principle remains the same. Color discrimmation as such is 

 not a part of our problem, and colors were used only for the sake 

 of a possible reinforcing value. 



Per _ White pedal card 



„ trrors ^ , 



Lent onlv. 



Color pedal cards and sign boards. 



Same with 

 odors. 



Odors 

 alone 



Fig. 2. Explanation of Table of Curves. Each of the dots connected by the closed lines represents 

 the percentage of correct first choices in 20 trials; each of the dots connected by the broken lines repre- 

 sents the total number of errors in 20 trials. 



Where stars (**) are used in place of dots, sets of experiments in which electricity was used are 

 indicated. 



The heavily shaded horizontal line upon which the figures "25" and "30" stand, is the average chance 

 .line mentioned in the text. 



Our results demand two general analyses: (i) An analysis of 

 errors, i. e., of the number of times that unattached pedals were 

 struck, and of the factors determinative of these inadequate reac- 

 tions; (2) an analysis of the correct and incorrect first choices. 

 It may be well to remind the reader that the pedal which the animal 

 struck first during a given trial is recorded as his first choice for 

 that trial. 



