168 BEGINNINGS OF INTELLIGENCE 



agency which preserves or repeats certain activities and re- 

 jects 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 role similar 

 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 advantageous 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 reinforced in different 

 conditions to which it may be adapted. Instinctive fear 

 may be modified through experience so that it is no longer 

 attached to objects that are found to be harmless, while it may 

 be intensified in relation to other objects that are found 

 to be sources of injury. Where there is hesitation between 

 the exercise of two instincts such as the tendency to pursue 

 an animal as prey, and the instinctive fear which that animal 

 may awaken, experience may quickly point out which 

 proclivity is the more advantageous to follow. The pleasure- 

 pain reaction enables an animal to select, so to speak out of 

 its stock of instinctive endowments those responses which 

 are best adapted to the particular situations that confront 

 it. It is a means of adapting instincts to new or inconstant 

 conditions and thus of effecting a closer adaptation to the 

 environment than that which would be possible by following 

 purely congenital modes of response. The development of 

 the pleasure-pain reaction marks one of the most important 

 steps in the evolution of behavior, for the entire super- 

 structure of intelligence in all its stages is based upon it, 

 and it is not surprising that many writers regard it as an 

 index of the beginning of consciousness, a point where a new 



