Cole, lutelligetice of Raccoons. 229 



culty of one person alone having to display the colors, feed the 

 raccoon and keep the record, my notes are not perfectly reliable 

 in respect to the exact number of times required for the mastery 

 of each pair of colors. Consequently when a pair of colors seemed 

 to have been mastered, each animal was given a final test of either 

 twenty-five or fifty trials, an experienced assistant keeping the 

 record. If out of twenty-five trials there were at least twenty- 

 three correct reactions, or out of fifty trials at least forty-five, I 

 assumed that the colors were discriminated. In most of these 

 final tests the raccoon never failed to react to the right (food) card 

 and never attempted to react to the wrong one. The response 

 demanded of the animal was that he mount a box 2\ feet high by 

 means of another 15 inches high which served as a step to the 

 first, when the food-card was displayed, and that he refuse to go 

 up when the other card appeared. If he started up but returned 

 at once after a second look at the no-food card, the reaction 

 was recorded as correct. If he did not come back immediately 

 from the lower box, the reaction was recorded as incorrect. On 

 the other hand, he was required to go to the top of the two steps 

 when the food card w^as displayed. 



According to the above standard the animals learned to dis- 

 criminate the following pairs of cards of diflPerent colors and inten- 

 sities. 



No. 4. Black-white, Black-yellow, Black-red. 



No. 3. Black-white, Black-red, Black-blue, Black-yellow, 

 Black-green, Blue-yellow. 



No. 2. Black-white, Black-red, Black-blue, Black-yellow, 

 Black-green, Blue-yellow. 



No. I. Black-white, Black-red, Black-blue, Black-yellow, 

 Black-green, Red-green. 



By this method also it always required many more trials for the 

 discrimination of red from green, or blue from yellow than for 

 the discrimination of black from white, or of black from the colors. 

 The female. No. 4, though given many trials, did not succeed 

 in discriminatmg red from green, nor blue from yellow, hence in 

 this case the brightness difference seemed too slight to serve as a 

 means of distinguishing the colors. Further evidence that No. I 

 distinguished cards of different colors and intensities is given on 

 p. 256. The fact of his discrimination of the series white, orange, 

 blue, from the series blue, blue, blue, whether each series was 



