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HARVEY CARR 



and vice versa. The mastery of one path was made at the 

 expense of an increased number of wrong choices of the oppo- 

 site path. In the final periods of learning, however, the two 

 habits were brought up to the same degree of perfection and 

 progressed together. In all four of these cases the left path 

 proved to be the easier and was mastered first. The reverse 

 situation obtained for the other four animals. Progress in one 

 habit was almost invariably associated with progress in the 

 other. The two curves were thus similar in form. Typical 

 examples of these relations are represented in figures 5 and 6. 



Figure 5. — Graphs R and L, curves of Figure 6. — Graphs R and L curves, of 

 mastery of the right and left exits re- mastery of the right and left exits re 

 spectively. spectively. 



The graphs L and R represent the progressive mastery of the 

 left and right paths respectively. In fig. 6 the two habits antag- 

 onize each other's progress in the main, and the left position 

 is the first to be mastered with any degree of perfection. In 

 fig. 5 the two positions are mastered simultaneously, although 

 the right habit maintained somewhat the higher degree of per- 

 fection for most stages of development. 



During the solution of the problem, the animal may develop 

 several modes of attack. 1. The rats may acquire a position 

 preference, or they may distribute their choices equally between 

 the two exits. A fixed preference for either of the two exits 



