244 F. M. GREGG AND C. A. McPHEETERS 



With the premature responses, the "turning back" proves not 

 only the effectiveness of the final card, but 'it is assumed that 

 this behavior was instigated by an anticipatory image of that 

 card. We are told that this final red was an anticipated and 

 expected color "which they (the animals) generally waited to 

 see but sometimes were too eager to wait for." 3 



The essentials of Cole's apparatus and method w 7 ere dupli- 

 cated in our experiment. The main difference consisted of the 

 introduction of a large screen to hide the experimenters. Our 

 apparatus is represented in figure 2. Our operator, usually 

 Mr. Gregg, stood at the rear right hand corner of the table and 

 observed the raccoons through a 1 cm. opening, A. He manipu- 

 lated the levers, F, by pulling the cords, C, which passed from 

 the ends of the levers down through pulleys on the floor, B, 

 and up to a point within easy reach of his right hand. The 

 levers were limited in their range of movement by elastic cords, 

 D, attached at their lower ends to the table and at their upper 

 ends to an upright bar. This arrangement kept the levers 

 hidden when not in use, and reduced the noise of the operation 

 to a min'mum. The board screen, E, was about five inches 

 high. The color cards, F, were two inches square, and w T hen 

 elevated above the board they were practically on a level with 

 the eyes of the raccoons. The distance between the elevated 

 positions of contiguous cards was approximately one -half inch. 

 The levers were similar in form, size and appearance. The dis- 

 tance between the levers and the feeding steps, G, was two feet. 

 The observer and recorder, usually Mr. McPheeters, stood at 

 the shelf at the front and right end of the table. All of his 

 body with the exception of his head was screened from the view 

 of the animals. 



The positive series consisted of white, blue and red cards 

 presented in mmediate succession. Mounting the steps was 

 considered a successful response and this reaction was rewarded 

 by a morsel of food received through the hole, I. Figure 3 

 represents Jill in the act of feeding. Any tendency to prema- 

 ture response in this series was punished by the withholding of 

 food. The red card presented three times in succession con- 

 stituted the negative stimulus. Remaining off the steps was 

 regarded as a successful response, but no food was given either 

 3 Op. cit., p. 258. 



