226 'Journal of Comparative Neurology and Psychology. 



of seven and two-tenths seconds and remembered the combina- 

 tion better. Were raccoon No. 3 a human being, we should have 

 no hesitation in saying that he had to give closer attention to the 

 mechanism in order to learn it. If the learning were nothing 

 more than the formation of a habit, No. 2, who had had more 

 experiences with the combination, should have been superior in 

 operating it after a long time interval. Additional memory tests 

 will be described in connection with the tests of discrimination. 



DISCRIMINATION. 



Fisual Discrimination. — -In the tests of visual discrimination no 

 attempt was made to determine whether the raccoons distinguished 

 colored objects by differences in color or by differences in bright- 

 ness. In fact, the greater number of trials required to distinguish 

 two colored objects as compared with the number required to dis- 

 tinguish white from black is, in so far, evidence that the animals 

 were reacting to brightness alone and that the dimmished differ- 

 ence in brightness rendered discrimmation more difficult. The 

 tests for discrimination of colored objects presented in succession 

 led naturally to a test for the presence of visual images and this 

 question was investigated rather than that of color-vision. I hope 

 in the future to test color-vision. Meanwhile, where colors are 

 named in this and succeeding sections it will be understood that 

 colors exclusive of brightness differences are not implied. 



In the first tests a modification of the apparatus used by Kinna- 

 MAN in his study of the color perception of monkeys was employed. 

 Two ordinary drinking glasses were covered on the convex sur- 

 face with papers of different colors. Of one pair, one glass was 

 covered with white paper, the other with black; of another pair, 

 one was covered with red, the other with green. The black and 

 white papers were of Milton Bradley manufacture and were of the 

 same intensity respectively as his black and white Maxwell disks. 

 The red and green also were the Bradley standard colors. 



In the experiments a bit of food was placed in one glass and 

 the glasses were then brought into the view of the animal and 

 placed side by side on the floor, from six to thirty inches apart in 

 different trials. An assistant set the raccoon free facing the two 

 glasses. The animal came to the glasses and secured the food. 

 He was returned to the assistant, food was put in the same glass 



