Considerations on the Problem of Learning 147 



ditions which are decidedly unwholesome. 



Ordinarily, pleasant tastes and smells retain very 

 nearly their original algedonic quality. We may 

 become more apt to seek a particular taste that we 

 have had before, but this in no way goes to show 

 that the original response set up by the pleasant 

 substance takes place more easily or is attended with 

 greater pleasure. Pleasures often wear away, and 

 things once agreeable may come to pall upon us. 

 There is little evidence that pleasure-giving stimuli 

 in general tend to reinforce themselves, and where 

 reinforcement occurs it is probably due to second- 

 ary associations with other reflex arcs. 



The effects of agreeable and disagreeable states 

 upon subsequent reactions to the stimuli immedi- 

 ately producing them are much the same. Consid- 

 ered as single responses both may be fatigued by 

 repetition and influenced similarly by general bodily 

 conditions. The notable thing about unpleasant 

 responses is that they exercise their inhibitory in- 

 fluence on other reflex systems. It is chiefly in their 

 influence on other associated reflex aires that the dif- 

 ferent effects of agreeable and disagreeable stimuli 

 become manifest. The nasty caterpillar in the 

 mouth of a chick may not become less disagreeable 

 when picked up on subsequent occasions, nor the 

 edible worm may not give a more intense thrill of 

 satisfaction, but the experience with the nasty cater- 

 pillar tends to check the pecking reflex, while the 

 seizure of the edible caterpillar tends to reinforce 



