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



criminated between these two groups of lever positions in 88% 

 of 17 trials. 



1 1 . The three levers were practically identical so far as form, 

 size and appearance are concerned. To test the possibility that 

 the levers were distinguished on the basis of their individuality 

 as tactual or visual objects, rather than on the basis of their 

 positional differences, the levers were interchanged in posi- 

 tion. Lever 1 was placed in the second position, lever 2 in 

 the third position, and lever 3 was given the first position. The 

 cards were removed, and the normal order of position was 

 given. No disturbance resulted. 



12. The original series, both of colored cards and of lever 

 order was alternated throughout two days' experimentation 

 with a series in which the cards were removed but the normal 

 lever order maintained. These tests were introduced to sub- 

 stantiate more thoroughly the contention as to the ineffective- 

 ness of the cards. The tests prove that the presence of the 

 cards is not only unnecessary for discrimination but also that 

 their presence does not materially increase the accuracy of 

 that discrimination. An accuracy of 94% was secured for 55 

 trials when the cards were present. Absence of the cards gave 

 a percentage of 92 for 53 trials. 



13. This test was designed to determine whether the "posi- 

 tional ' ' difference between the two temporal series of lever 

 presentations was apprehended by means of vision or touch. 

 The color cards were used and the normal lever order was main- 

 tained. A plate of window glass 18 x 24 inches was placed 

 immediately in front of the levers. This glass effectually pre- 

 vented all contact, but it in no way disturbed vision. The 

 animal was allowed 20 minutes to become accustomed to the 

 new situation. Neither timidity, nervousness, nor curiosity were 

 manifested. During the two days' experimentation, tests were 

 taken both with and without the presence of this glass, all other 

 conditions remaining constant. Without the glass, behavior 

 remained normal in every respect. The presence of the glass, 

 however, destroyed the coordination. The animal's attitude 

 was one of bewilderment. The first 11 trials were all incorrect. 

 The raccoon soon learned to react either to the visual appear- 

 ance or noise of the levers, but she responded to every presen- 

 tation, both positive and negative. In other words inhibition 

 to the negative series ceased ; discriminative ability was destroyed. 



