DELAYED REACTION 3 



ulus (object) or movement that is represented. In the present 

 historical section the attempt is made: (i)To present the main 

 types of behavior that have been used as evidence of the exist- 

 ence of images in animals; and (2) to show that this evidence 

 is inconclusive, because the behavior may be stated in sensori- 

 motor terms. In the light of the assumption just made, there 

 are two reasons why this behavior may be so interpreted: (i) 

 The stimuli determining the reactions in question have not been 

 adequately known; and (2) inasmuch as this is true, one has 

 no right to assume the absence of the stimuh which are sup- 

 posed to be represented. All of the behavior that is summar- 

 ized in this section may have involved representative actors. 

 The point of my criticism will be that they need not have in- 

 volved such processes. It is 'not merely a question of the appU- 

 cation of the law of parsimony, as that is usually stated. It 

 is also a recognition of the fact that sensori-motor behavior 

 is genetically the more fundamental form. 



The following are the types of evidence to be considered: 

 (i) Imitation; (2) use of tools; (3) dreams; (4) nature of the 

 learning curve; (5) memory; (6) Thorndike's test: The imme- 

 diate reaction to one stimulus before tjie appearance of a second 

 which has always accompanied the first after an interval of 

 a few seconds; (7) recognition; (8) learning by being "put 

 through;" (9) rate of forgetting; (10) association by similar- 

 ity; (11) reluctancy and expectancy of response; (12) vary- 

 ing means to the same end; (13) reactions to a temporal series 

 of colors, and (14) Washburn's cat on the stairway. 



1. Imitation 



Thorndike =* is an example of the comparati\-e psychologist 

 who interprets the highest type of -imitation as requiring the 

 presence of images or ideas. In his experiments, however, he 

 found no evidence for the existence of this kind of behavior. 

 The general character of the imitation experiment is well known. 

 An animal that has failed to solve a certain problem is con- 

 fined where it can see another work the mechanism and get 

 food. It is then given an opportunity to make the desired 

 reaction. If the trial succeeds or if there is a sudden improve- 

 ment in the animal's behavior, it is said to have profited by 



3 Thorndike, E. L. Animal Intelligence. 1911, New York, pp. 76-108. 



