LOCALIZATION OF LEARNING PROCESS 197 



in the open box (Fig. 49, 1) activates the innate neuro- 

 muscular mechanism and the rat goes directly to the 

 food. At the beginning of training the door of the 

 food-box is closed (Fig. 49, II) and the natural reac- 

 tion is blocked. There immediately follows direct at- 

 tack upon the food-box, with perhaps some clawing 

 and gnawing, followed by random exploratory move- 

 ments. In the course of these movements the latch is 

 accidentally tripped, the door flies open, and the way 

 to the food is unimpeded. The consummatory reac- 

 tion promptly follows through the same final com.mon 

 path as originally employed. After, say, a hundred 

 such experiences the habit is fixed and the rat goes 

 directly to the latch and after sensing this contact he 

 goes directly to the food (Fig. 49, III). 



This is the overt behavior. We do not know exact- 

 ly what takes place in the central nervous system dur- 

 ing this process. The evidence seems to indicate that 

 upon blocking of the natural response there is summa- 

 tion of excitations in the center with more or less dif- 

 fuse spreading of the excitation through such nervous 

 pathways as may be available (p. 135). The resulting 

 movements may be direct but futile attack upon the 

 object or random activity. Some particular sequence 

 of these movements results in satisfaction. After this 

 result has been achieved a sufficient number of times, 

 the familiar physiological principle of facilitation of 

 path by use is manifested, and, as Sherrington expres- 

 ses it, the appropriate pathway is smoothed by sheer 



