368 



HARVEY CARR 



The animals were required in the initial trial of each day to 

 choose the right exit in order to secure food. Alternation was 

 the rule for the remaining trials of that day's test. Mastery of 

 these initial trials thus represents a different type of problem 

 from that involved in the subsequent alternation. For this 

 reason separate records were kept of these initial trials and 

 the results were plotted and the curve compared with that 

 representing the mastery of the problem as a whole. 1. Mastery 

 of this initial choice proved to be extremely difficult for the 

 majority of the animals. Five rats consistently made poorer 

 records for the first trial than for the whole day for all stages 



Trials |7Q 



Figure 2. — Curves of learning-. Solid line, group curve; broken lines, typical 

 individual curves; curve from A to B, progress of group during period when 

 control tests were given. 



of learning. Only one rat found the initial choice to be easy 

 and reversed the above relation. 2. Seven of the eight animals 

 made poorer records for the initial choice at the middle of the 

 learning period than at the beginning. With one exception the 

 curves for the initial choice exhibit a pronounced descent for 

 the first stages of mastery. 3. With four animals progress in 

 the mastery of the initial choice was correlated with the degree 

 of success for the day, although these choices were the more 

 difficult. In these cases the mastery of the problem as a whole 

 was apparently dependent upon the ability of the animal to get 

 the day's sequence started properly. With the remaining four 

 animals, these two aspects of the problem were apparently not 

 related. 4. All animals finally succeeded in mastering this 



