The Beginnings of Intelligence 131 



formation of a simple association. And it is a prob- 

 lem which, despite its apparent simplicity, involves 

 the consideration of some vexed and subtle ques- 

 tions. 



In learning we have to do with two opposite 

 processes of reinforcement and inhibition. A chick 

 after it pecks at a caterpillar which is wholesome 

 and savory pecks at a similar caterpillar more read- 

 ily on a second occasion. Something has apparently 

 reinforced the connection between the visual impres- 

 sion produced by the caterpillar and the pecking im- 

 pulse. If, on the other hand, the chick pecks at a 

 caterpillar having a nasty taste it is apt to avoid 

 pecking at it a second time. Something has hap- 

 pened to inhibit the response that would otherwise 

 occur. We commonly explain such behavior by 

 ascribing to the creature feelings of pleasure and 

 pain. We say that the chick pecks at one kind of 

 a caterpillar because of the pleasant taste it de- 

 rives, and avoids another variety because its taste 

 is bad. Pleasure and pain apparently function as 

 agents for the reinforcement of certain reactions 

 and the stamping out of others. It is a general 

 rule, though not without certain exceptions, that 

 what affords pleasure is conducive to organic wel- 

 fare, while that which is productive of pain is in- 

 jurious. The upshot is that the associations that 

 are the outcome of the pleasure-pain response are of 

 just the kind that minister to the animals' needs. 

 Beneficent arrangement! Apparently we have to do 



