PLEASURE, PAIN AND INTELLIGENCE 147 



when placed in the box a second time. After a number of trials 

 the cat will come to make the right movements for escaping very 

 soon after being placed in the box and its various useless random 

 movements will be discontinued. The connection between the 

 perception of the mechanism of escape in the box and the act neces- 

 sary to gain its liberty comes to be more and more firmly estab- 

 lished in the cat's brain with repeated experiences. The cat 

 perceives a number of things in the box and performs a number 

 of different acts but out of all these, associations are formed only 

 between certain stimuli and those responses to them which bring 

 pleasure to the animal. 



Pleasure and pain therefore have apparently a fundamental 

 connection with the development of intelligent responses out of 

 instinctive activity. Were there not something to clinch or 

 strengthen the connection between certain stimuli and the ap- 

 propriate responses to them the organism might perform random 

 movements till doomsday without being a whit better off. It 

 is a problem therefore of fundamental importance to ascertain 

 in what the mechanism of this ability to profit by experience 

 essentially consists. It is not mere habit, not the mere making 

 more permeable certain preformed connections in the brain. One 

 act would then be just as apt to be followed up as another. 

 Whether an act tends to be followed or not depends on what it 

 brings to the organism. Apparently we have to do with a selective 

 agency which preserves or repeats certain activities and rejects 

 others on the basis of their results. 



The importance of random movements lies in the fact that they 

 offer opportunities for making favorable adjustments. For the 

 development of intelligence they play a similar role to that of 

 variations in the process of evolution. The animal that does the 

 most exploration is the one most likely to hit upon new advan- 

 tageous adjustments. In the same way intelligent adjustments 

 as James has contended are favored by a multiplicity of instincts, 

 especially if these instincts are of a contrary or conflicting nature, 

 for now one and now another instinctive tendency may be rein- 

 forced in different conditions to which each may be adapted. 

 Instinctive fear may be modified through experience so that it is 



