70 STELLA BURNHAM VINCENT 



A. The Value of the Use of Contact Senses in the Study of Discrimination 



The greater part, indeed almost all, of the "so-called" dis- 

 crimination experiments with higher animals has been made 

 with the help of the distance senses. This is also true of the 

 experiments in imitation and association which involve dis- 

 crimination. The contact senses always play some part, to be 

 sure, but the distance sense is the one which is being tried out 

 and usually this sense is vision. It is not singular, therefore, 

 that in the use of a sense so late in phylogenetic development, 

 and in many animals so weak, there should be such conflicting 

 opinions as to the process of discrimination itself in animals. 



The contact senses are probably of far greater value in the 

 lives of the lower animals than we realize and we are very apt 

 on the other hand to over-emphasize the importance of -the 

 higher senses. The associations also, in the experiments using 

 visual cues, have not been native vital ones. It is doubtful 

 whether visual discrimination is ever the direct stimulus to a 

 rat's quest for food, yet in experiments it has been made to 

 serve this purpose. The lights, colors, etc., which have been 

 used have been stationary yet it is well recognized that moving 

 objects are those to which animals respond most quickly.^' 



For students of animal behavior the advantage of the use of 

 other senses is great. If psychic processes are to be inferred 

 from behavior there must be behavior to observe and there is very 

 little of this in the reactions to visual and auditory stimuli. As 

 a rule only the final act is seen and all the intervening steps are 

 hidden. Yet the discussions of animal intelligence are based, 

 for the most part, entirely on such experiments. The conclu- 

 sions are not fair to the animal. On the other hand, when con- 

 tact senses are employed, there is a far greater amount of ob- 

 servable activity — activity which reveals stages of development, 

 which changes from day to day and from trial to trial, and 

 which gives our inferences far more justification as well . as 

 plausibility. 



No one can tell when an animal sits and looks at two lights 



or two colors and then responds with certain conduct what has 



happened in the preliminary interval. Of course the inference 



. is equally impossible in regard to some of the other senses to 



^' Yerkes, R. M.: The Discrimination Method, Jour. Animal Behavior, 1912, 

 vol. 2, no. 2. 



