CHAPTER III 



REFLEX ACTION AND CONDITIONED 

 ACTION 



The subconscious of a civilized adult reflects all the 

 habits he has acquired. 



— John Dewey 



THE basic function of the cerebral cortex is 

 the correlation and integration of the ele- 

 ments of behavior sequences so that these 

 follow in ways most appropriate for promoting the 

 welfare of the organism as a whole. Here, as so often 

 in biology, the genetic approach offers promise. As 

 this inquiry advances it will be clear that in the course 

 of the evolution of the cerebral cortex it has been 

 slowly elaborated from raw materials originally pro- 

 vided by primitive correlation centers of the fore- 

 brain which do not differ in principle from those of 

 the medulla oblongata. We shall, accordingly, next 

 examine briefly the steps in the differentiation of 

 correlation centers in general. 



In the simple reflex, such as withdrawal of the 

 finger from a pin prick, we have theoretically a one- 

 to-one relation between stimulus and response like 

 the ringing of a bell when the push-button is pressed. 

 This is never realized in practice, for there is always 

 some spread of the excitation with various other 

 complications. If two or more sense organs are 



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