Cole, Intelligence of Raccoons. 23 1 



The animals had completed the visual discrimination tests 

 before they were tried with this pitch discrimination. 



Discrimination of Forms. — For experiments in the discrimina- 

 tion of forms and sizes the card-displayer already described was 

 used. Cards of different forms or of different sizes were substi- 

 tuted for cards of different brightness and color. In the tests for 

 form discrimination the animal was fed when a square card 6x6 

 inches appeared and not when a circular one 6 inches in diameter 

 was shown. If the animal formed an association between the 

 square card and food so that he went to the top of the high box 

 to be fed when that card was shown and refused to go up when the 

 circular card appeared, we may say that he discriminated. My 

 purpose was to test the discrimination of two objects widely dif- 

 ferent for the human eye, not to test the delicacy of discrimination. 



The results for form discrimination given by No. 2 and No. i 

 appear below. Both animals had already discriminated differ- 

 ently colored cards by this method, so that attention to the cards 

 was well established and the form test proved to be very easy. 



TABLE V. 



No. I. No. 2. 



Square. Circle. Square. • Circle. 



Right. Wrong. Right. Wrong. Right. Wrong. Right. Wrong. 



1-50 38 12 35 15 43 7 41 9 



51-100 47 3 47 3 42 8 39 II 



101-150 48 2 44 6 



As a matter of fact, these two cards differed in size as well as in 

 form, but for sensation (barring judgment) I thought this circle 

 to have more nearly the value of the square than one of exactly 

 equal area. However, anyone who will compare two circles with 

 radii of 3 and 3/0 inches respectively will, I think, find their 

 visual difference very slight. 



Discrimination of Sizes. — No. 2, No. 3, and No. 4 were tested 

 in the discrimination of sizes by the method used in the form dis- 

 crimination. Two square cards 6^ x 6^ and 4J x 4^ inches were 

 used. They were first shown alternately, then in varying order. 

 The rapid learning which occurred is due to much previous train- 

 ing in brightness discrimination by this method. It is evident 

 that each animal began to form the association within the first 

 fifty trials, and that learning not to respond to the small card pro- 

 ceeded more slowly than learning to go up when the large card 



