BEHAVIOR OF VERTEBRATES 415 



conclusions are illustrated in the critique of Cole's experiments 

 with raccoons made by Gregg and McPheeters (22). These 

 men repeated Cole's work in which the animals were taught 

 to discriminate between two temporal series of stimuli. As will 

 be remembered colored cards were used. They were raised above 

 a screen by a series of levers. The animals were taught to react 

 positively to W.B.R. and negatively to R.R.R. Cole concluded 

 that the discrimination was made by means of vision, that it 

 was presumably based upon brightness and that all three presen- 

 tations of the series were effectual. He thought that the " carry- 

 ing over " of the stimulating effects of the first two cards till 

 the final response must be the result of an imaginal process. 

 Only two raccoons were used in the Chicago experiments. One 

 of these learned to respond in a fashion similar to Cole's animals. 

 A control series of experiments included: the exchange of R.W. 

 cards, change of operators, use of fresh color cards, washing 

 levers, change of lever order, substitution of entirely different 

 colors, use of bare levers without cards, and use of glass screen 

 before levers. The conclusion was reached that the discrimina- 

 tion was based primarily upon an apprehension of the relative 

 spatial position of the levers which was mediated through nose 

 contact in active, not passive, touch. The discrimination seemed 

 to be based exclusively upon the difference between the first 

 members of the groups which resulted in the setting up of cer- 

 tain motor attitudes. The third member was common to the 

 two groups and hence could not serve as a basis for discrimina- 

 tion but it did serve to release the discriminative response which 

 had been set up by the previous stimuli. The functional rela- 

 tion of the second member of the series was not worked out. 

 The authors do not deny that raccoons have and may use visual 

 images but say that Cole's experiments do not prove their 

 existence as the " carrying over " may be by means of motor 

 attitudes. 



In Johnson's (29) work with dogs, some of the puppies 

 were made temporarily blind by having their eyelids sewed to- 

 gether before they had gained their sight. In the latter part of 

 his monograph he attempts to give an account of the learning 

 time and the learning methods of these blind dogs as compared 

 with normal dogs. The problem was the opening of cage doors, 

 having different kinds of latches, under the stimulus of hunger. 



