158 Studies in Animal Behavior 



organism tries again, and keeps on doing so until it 

 attains ultimate success. 



"Error" generally means any act prejudicial to 

 organic welfare. The lower organisms are like 

 ourselves in avoiding things which are injurious and 

 in remaining under beneficial conditions, whether 

 or not they are influenced thereto by similar psychic 

 states. Jennings feels "compelled to postulate 

 throughout the series certain physiological states to 

 account for the negative reactions under error, and 

 the positive reactions under success," but the search 

 for such states, as I have elsewhere attempted to 

 show, is probably a vain quest. 



In behavior of the trial and error type, success 

 is attained, not by a direct adaptive reaction, but 

 by checking or reversing all reactions except the 

 right one. The final outcome of the varied move- 

 ments is adaptation. The method is roundabout 

 and expensive, but it is better than nothing. It is 

 Nature's way of blundering into success. 



The capacity to gain anything through the method 

 of trial and error presupposes that an animal's re- 

 actions to beneficial stimuli are different from its 

 reactions to injurious ones. There is, as I hope 

 to make clear, no way of acquiring this capacity 

 unless there is a congenital basis of adaptive re- 

 sponse to start with. We are led to the conclusion 

 that the adaptive character of the indirect adjust- 

 ments effected through the method of trial and 

 error is, like the adaptiveness of direct instinctive 



