LOCALIZATION OF LEARNING PROCESS 195 



cerebrum has proved to be necessary for the learning 

 of the double platform box and no single part has 

 proved to be significantly more efficient in learning 

 than any other part. For the acquirement of this hab- 

 it the various parts of the cerebrum seem to be abso- 

 lutely equipotential." And again he asks (p. 103), 

 "What becomes of the concept of sensory and motor 

 projection areas if the entire cerebral cortex of the rat 

 is equipotential in learning?" 



This raises the question, whether in the rat the 

 correx participates at all in the acquisition of simple 

 trial-and-error habits of the sort here under considera- 

 tion, and, if so, in what manner. Throughout the ex- 

 perimental series there is marked contrast between 

 the learning process and the retention of normally 

 formed habits. 



The establishment of these habits of conditioned 

 response type is an aspect of organic memory (with no 

 necessary implication of psychological memory). In 

 any mnemonic process we must distinguish three as- 

 pects: learning, retention, and recall. When a differ- 

 entiated nervous system is involved the initial learn- 

 ing process presumably effects some enduring change 

 in the internal organization of the correlation centers 

 such as to facilitate a type of response different from 

 that previously called forth by the stimulating situa- 

 tion. In the latch-box experiment we may schematize 

 this process somewhat as follows. 



In the untrained animal the presentation of food 



