FUNCTION OF VIBRISSAE IN BEHAVIOR OF WHITE RAT 79 



to function either in the reinforcement of stimulation, or in the 

 setting of the synapse in more exact adaptation, or in secondary 

 sensation, or in giving higher intensity under attention; while 

 the psychologists Ktilpe,'* Wundt'" and others explain after 

 images, secondary sensations, and memory images correlated 

 with peripheral sensations by the same fibers. Much of the 

 recent work on imagery, particularly that of the Wurzburg 

 school, has failed to show that degree of clearness of imagery 

 in the thought processes which had previously been supposed 

 to be there and has forced a re-examination of the elem^ents in- 

 volved in reflective thought. The theory of peripheral sen- 

 sations centrally initiated which function in control '.n some 

 simple form has some foundation in fact. 



Why should not, therefore, some such simple sense elements, 

 far more representative of sensations than perceptions, call them 

 images if you will, we will not quibble over words, function in 

 the life of animals? Stripped of the rich associations which 

 human thought adds to them and the rich variety and com- 

 plexity which human sense experience would give them, they 

 must be very meager indeed, yet distinct enough to form a 

 part of the meaning which the past has given, and memory 

 preserved, and to which the animal reacts so typically. 



It is not insisted that the completed act may not follow, 

 when learned, from direct stimulation at the entrance to the 

 runways or that the association may not in most cases be be- 

 tween activities. What is insisted is the fact that in a situation 

 where the stimulus which is the cue must be actively sought, 

 where space conditions are constantly changed, there is strong 

 presumptive evidence that the sensory experience is a discrim- 

 inated one. Not that such experience is ever entirely separate 

 from the act, that could not be, but that it arises as a result 

 of it and in turn sets up a new series of activities. This pre- 

 sumption is further strengthened by observations of activities 

 in which this sensory stimulus only proves effective when in 

 contrast with its opposite, when an animal must always have 

 the two experiences before the final act occurs. Then there is 

 the behavior at the plate. Here there was pain associated with 

 contact followed by excessive activity. Later the activity was 



39 Kiilpe, Oswald: Outlines of Psychology (Eng. trans. 1893), pp. 83, 183. 

 ^"Wundt, Wm.: Principles of Physiological Psychology, (Eng. trans. 1904), 

 vol. 1, p. 182 et seq. 



