HOW DO RATS LEARN? 167 



the acquisition and utilization of individually learned 

 experience as contrasted with those racial traits em- 

 braced under the terms "reflex" and "instinct." The 

 rat's cortex has the same fundamental organization 

 as the human, but simplified almost to the limit com- 

 patible with the recognition of this fundamental plan. 

 The rat's behavior is similarly simplified. Now, learn- 

 ing is an aspect of behavior which readily yields itself 

 to accurate investigation by quantitative objective 

 methods, and the learning processes of normal rats 

 have been intensively studied in this way. According- 

 ly, Lashley undertook a systematic exploration of the' 

 part played by the cortex of the rat in the acquisition 

 of various habits. Some of the problems set were as 

 follows. 



1. Is the apparatus of learning restricted ex- 

 clusively to the cerebral cortex.? Obviously not, for 

 worms and most other invertebrates can acquire "as- 

 sociative memories," that is, can learn, though they 

 have no cerebral cortex whatever, and animals as high 

 in the scale as dogs if deprived of the cortex still can 

 acquire simple habits. Lashley 's experiments on rats 

 strongly confirm this conclusion. 



2. Though the learning process is not restricted 

 to the cortex, is there "any sort of nervous organiza- 

 tion which is particularly well adapted for learning"; 

 are there "any structures whose functional activity 

 facilitates learning" (1920, p. 6^) ? This theme is dis- 

 cussed by Lashley very briefly and quite inadequate- 



