A STUDY OF THE BEHAVIOR OF THE CROW 83 



during our experiments from 15 to 60 seconds, in an attempt to 

 discover the most satisfactory length of confinement. At the 

 proper moment, the experimenter opens the entrance door and 

 the crow is allowed to retrace its steps. It may then immedi- 

 ately make another choice. But not until it enters the right 

 compartment, is it awarded with food and allowed to return 

 to the fly. Thus punishment for incorrect choices is combined 

 with reward for correct choices. 



In further description of the apparatus, it should be said that 

 wire partitions at each side of the multiple choice box, and 

 extending from the lid of the same to the roof of the fly, prevented 

 the crow from walking or flying over the box, while boards both 

 in front of the box and behind it and on a level with its floor form 

 a floor which prevented the bird from getting under the box. 

 The only possible course for the subject from main entrance 

 to main exit door is by way of one of the compartments. 



Experience shortly indicated that the crows could be used 

 most satisfactorily if given their trials alternately, and the method 

 finally settled upon was that of admitting one crow to the appar- 

 atus, allowing it to make its choice, and then holding it in the 

 passageway beyond the exit doors until the other crow had 

 passed through the main entrance door into the reaction chamber. 

 Thus, as one subject emerged from a compartment of the box E, 

 the other bird entered the reaction chamber. When, as some- 

 times happened, the one or the other bird failed to respond 

 immediately and appropriately and both were in the fly, it was 

 fairly easy for the experimenter to admit the proper bird by 

 carefully manipulating the entrance door. 



PRELIMINARY TRAINING 



The crows obtained almost all of their food in the multiple 

 choice box. In order that they should work steadily and indus- 

 triously, it was necessary to have the pieces of bread or mouse 

 meat, which was sometimes used instead of bread, very small. 

 It proved possible to obtain as many as twenty reactions per 

 day from each bird, in series usually of five each. 



We shall now consider the course of experimentation and its 

 results. One June 21st, the crows having attained ability to 

 feed themselves, preliminary training was undertaken, and from 

 that time they were fed in the multiple choice box. They 



