THE ALTERNATION PROBLEM 



A Preliminary Study 



HARVEY CARR 



University of Chicago 



INTRODUCTION 



In the discrimination experiment animals are required to 

 choose between several paths according to some given temporal 

 scheme. It is recognized that the animals may ignore the 

 stimuli to be discriminated and solve the problem by reacting 

 to this temporal order of presentation. This possibility is 

 usually eliminated by several means: — 1. By instituting a se- 

 quence of such complexity that the animals are unable to master 

 it. 2. By varying the given temporal order after the problem 

 is mastered; and 3, by removing the stimuli and requiring the 

 animals to rely upon sequence alone. The control tests have 

 almost invariably shown that the sequence factor is relatively 

 insignificant in the solution of these problems. 



The ability of animals to master given sequences of position 

 habits has not been adequately investigated. Such a problem 

 presents several aspects of interest: — 1. The determination of the 

 limits of complexity which a given animal can master. 2. The 

 relative difficulty of sequences differing in kind and degree of 

 complexity. 3. The possibility of discovering new aspects of 

 the learning process. 4. The determination of the various con- 

 ditions conducive to the development of such habits; and 5, 

 the character of the sensori-motor mechanisms involved in such 

 series of alternating habits. 



This paper reports the results of an experiment which was 

 designed as a preliminary attack upon the above program. 

 Before designing and constructing an apparatus especially 

 adapted for this purpose, it was deemed advisable to test a 

 group of animals upon a simple sequence. For this purpose we 

 utilized a piece of apparatus which had been employed in the 

 study of a particular phase of the discrimination problem. The 

 essential features of this discrimination box are represented in 

 fig. 1. The center consists of a 2' x 3' rectangular area. Open- 



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