88 CHARLES A. COBURN AND ROBERT M. YERKES 



letter a, following a number, indicates that the bird was aided 

 in its choice by the experimenter. 



It is possible by careful study of this and succeeding tables to 

 discover the reactive tendencies of the organism, and to note 

 both the appearance and the disappearance of the same. 



Problem 1, the first door at the right, proved a very easy one 

 for both crows. It was mastered by number 3 after fifty-five 

 trials, and by number 4 after fifty-one trials. 



Table 2 presents the results of the various series of trials, 

 ranging in number from three to five for each subject. The 

 number of successes and failures in each series and the ratio of 

 successes to failures for each day appear. The letter R in this 

 table indicates correct first choices, the letter W, incorrect first 

 choices. The table has to do only with first choices. 



In contrast with the above results in problem 1, the first door 

 at the right, we present in table 3 a summary of the results for 

 problem la, the first door at the left, the trials for which were 

 given not immediately after those just described but at the end 

 of the season, and after the crows had for several weeks worked 

 on problem 2, the second door at the left. Naturally the influence 

 of their training to go to the second door retarded the formation 

 of the habit of choosing the first door at the left. For the satis- 

 factory solution of the problem, one hundred trials were required 

 by each bird. Doubtless a change of experimenters after trial 

 75 somewhat delayed progress. The results which appear in 

 tables 3 and 4 demand no further comment. 



Recurring now to problem 1 , it is obvious that from the human 

 point of view this is a very simple problem. The crows solved 

 it readily, but in the course of their work they frequently exper- 

 ienced discouragement and were aided in a considerable number 

 of their early trials by the experimenter. Doubtless our results 

 would be more significant had this aid been withheld, but at 

 the outset of our work we hesitated to run the risk of spoiling 

 our subjects by over-discouraging them. In problem la, no aid 

 was needed. 



Varied reactive tendencies do not appear in connection with 

 this problem. Very few wrong choices were made. Conse- 

 quently, all that can be gleaned from the results is a general 

 knowledge of the behavior of the crow in the face of a certain 

 fairly simple experimental situation. 



