146 Studies in Animal Behavior 



ity. According to the theory, responses involving 

 unpleasant effects should come to inhibit themselves. 

 Such a result might shield the neurones from fur- 

 ther injurious stimulation, but it would hardly be 

 conducive to the welfare of the organism in general, 

 since it should keep on reacting so as to avoid 

 sources of injury. That there is any general ten- 

 dency for unpleasant responses to become reduced 

 in vigor, apart from the purely temporary effects 

 of fatigue common to all responses, is very ques- 

 tionable. 



On the other hand, there is probably no general 

 tendency for pleasant responses to become per- 

 formed with greater vigor or to be accompanied 

 by heightened satisfaction. Learning to like cer- 

 tain articles of food as well as coming to dislike 

 others is probably a matter of secondary associa- 

 tion. Addiction to alcoholic drinks and other so- 

 called habit-forming drugs is a phenomenon rather 

 exceptional in character, the explanation of which 

 need not concern us at present. Doubtless second- 

 ary associations are involved here also. It is prob- 

 ably not the initial pleasure which these drugs arouse 

 that impresses the habit of using them (the sub- 

 cutaneous injection of morphine, for instance, is the 

 reverse of pleasant) , but some general physiological 

 effect which is pretty closely associated with their 

 injurious influence on the neurones. Under certain 

 kinds of intoxication a person may experience feel- 

 ings of pleasure that go along with cerebral con- 



