HUMAN REACTIONS IN A MAZE 121 



those stimuli which they have learned are probably of an incon- 

 sequential character. The wider the experience of an individual 

 in the world, the more blase, as a rule, he is likely to be. 



The same conception is applicable to animals. The behavior 

 of the young is characterized by an almost feverish, irrepressible 

 exuberance of activity of a highly random, impulsive, and pur- 

 poseless character. Mature animals act, as a rule, with some 

 degree of dignity, caution, and circumspection. They have 

 rather thoroughly explored their environment and classified it 

 in reactive terms. Their habits on the one hand have increased 

 their sensitivity to certain stimulative features as objects of 

 food and danger. On the other hand, habit has also curbed 

 and repressed responses to the trivial and inconsequential 

 aspects of the environment. As a result their energy is better 

 directed and conserved for the more immediate and practical 

 needs of the organism. The difference refers not only to the 

 amount of activity, but also to its character. 



This conception is applicable to differences between species, 

 e.g., the comparison of the rats and the human subjects in our 

 experiments, as well as to differences between adults and young 

 of the same species. An organism with the greatest capacity 

 for intelligence is, other things being equal, the most likely 

 to acquire the greatest number of these inhibitory habits, and, 

 as a consequence, is the least likely to give free rein to its dis- 

 cursive and random impulsive tendencies. 



This view suggests the general proposition that the func- 

 tional presence of higher mental processes inhibits and supplants 

 the " motor excess " characteristic of the trial and error method 

 of learning. Without the higher processes, the organism must 

 rely for success upon the number of random movements; when 

 conduct becomes guided more and more by higher processes, 

 the extreme tendency to " motor excess " is not only useless 

 but disturbing to the operation of the rational activities. This 

 suggests that the degree to which organisms rely upon and 

 utilize the trial and error method (excessive explorations) of 

 learning may be determined by innate tendencies as well as 

 by acquired habits and rational processes. An organism with 

 little capacity for the higher sorts of intelligence, is necessarily 

 constructed on the plan whereby this " motor excess " feature 

 of behavior is accentuated. With organisms of higher mental 



