CHAPTER IX 

 HOW DO RATS LEARN? 



The transition from learning to habit is a gradual one. 

 Habit formation is complete when the act is performed with 

 the minimum of afferent impulses^ /".<?., with the least atten- 

 tion. The nervous mechanism involved is essentially the 

 same after the habit has become firmly established as on the 

 first day the act was attempted, but the mechanism runs more 

 smoothly. There is no basis for the belief that habit formation 

 involves a lower order of nerve cells ^ or short cuts through the 

 central nervous system. 



— F. H. Pike 



IN this chapter we shall consider the learning 

 process of the rat in its relation to the cere- 

 bral cortex. Properly controlled experimental 

 knowledge of the intrinsic functions of the cerebral 

 cortex of animals below the mammals is so meager 

 that for present purposes we may pass this question 

 by and turn directly to a consideration of the func- 

 tions of the cerebral cortex of the rat. Here we have 

 a large body of experimental evidence derived chiefly 

 from the researches of Lashley and Franz.^ The prob- 

 lems suggested by these experiments will first be 

 briefly stated. 



It is generally believed that the cortex of man and 

 other higher mammals is especially concerned with 



' The titles of the more important works by these authors to which 

 reference is here made will be found in the Bibliography. 



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