414 STELLA B. VINCENT 



with the exception of the 500-day group in which there were only 

 12 rats. Among other things the writer says in her resume of 

 conclusions: — " Young rats learn the maze more rapidly than 

 the old ones, the rapidity with which the habit may be formed 

 decreasing with increase in age. The time for the execution of 

 a perfect run increases with increase in age, the oldest group 

 requiring twice as much time as the youngest. The most rapid 

 stage of habit formation occurs earlier in the learning process of 

 the younger animals than of the older." The same writer, 

 briefly, in this paper, more fully in another (12), discusses the 

 elimination of errors in the same maze. Her interest lay in the 

 question whether, in learning the maze, the useless movements 

 most closely connected with satisfaction — food — are the first to 

 be eliminated or whether the useless movements most remote 

 from the source of satisfaction — food — persist the longer. 



The distribution of effort in learning has, in the past, engaged 

 the attention of several in the animal field but Ulrich (30) this 

 year has made a more extended investigation. He formulates 

 his problem as an effort to determine how distributing the effort 

 over one, three or five trials per day would affect the rapidity 

 of learning, the degree of effort and the amount of retention. 

 Another question which engaged him was, do the relations found 

 .true in the learning of one problem hold good when two or three 

 problems are learned at the same time. The pieces of apparatus 

 concerned in these problems were the latch box, the circular 

 maze and the inclined plane box. The author says: — When 

 trials are distributed over several days learning is more economical 

 but more days are required to establish a habit than w T here sev- 

 eral trials are given on one day. When three problems are 

 learned abreast a much larger number of trials is required to 

 learn each of the problems than would have been required if 

 the animal had been allowed to learn only one problem at a time. 



The behavior of the pig was studied by Yerkes by means of 

 what he calls the multiple choice method (38). Yerkes says: — 

 " The experimenter seeks in using the multiple choice method 

 to present to his subject, no matter what its type, age or condi- 

 tion, a problem which may be solved by the perception of certain 

 constant relations or group of relations within the reaction 

 mechanisms. For example, the mechanism to be operated may, 

 in the case of one problem, be the middle one of the group, and 



