84 CHARLES A. COBURN AND ROBERT M. YERKES 



exhibited no fear, rapidly became familiar with the apparatus, 

 and acquired skill in making the trip from the main fly, through 

 the experiment compartment, back to the fly. For several 

 days, both the entrance and the exit doors of the compartments 

 were kept open. Then the situation was changed by the closing 

 of the exit doors, and the crows were trained to enter a compart- 

 ment and wait for their food. 



On June 27th, the first series of trials worthy of special mention 

 was given. The apparatus was in perfect working condition. 

 Food was placed on the floors of the several compartments ; the 

 exit doors were closed and the entrance doors were open. The 

 main entrance door was opened, and both birds were allowed 

 to enter the reaction chamber and go to the compartments for 

 food. As they entered the compartments, the exit doors were 

 opened and the entrance doors closed. Thus, by a series of 

 trials they were habituated to the opening and closing of the 

 doors and were taught to make the circuit promptly from the 

 main fly back to the same by way of the multiple choice box. 



On the following day, June 28th, the food was placed in the 

 food containers and the exit doors were closed. Number 3 

 entered the compartments rapidly and made the circuit usually 

 without delay, but number 4 at first refused to enter the compart- 

 ments. Within two days, it, however, was readily entering, 

 in its search for food. 



On June 28th, only three or four of the entrance doors to the 

 compartments were opened at any one time. In the previous 

 preliminary training all of the doors had been opened. Neither 

 bird showed any marked preference for a particular compartment 

 in the multiple choice box. 



On June 30th, the method was tried of confining one of the 

 crows in the crow room B, of figure 2, while the other was given 

 its trials. Later in the day, the birds were given another series 

 of trials alternately, the one being kept in the exit alley as 

 described on page 83, until the other had entered the reaction 

 chamber. This method proved satisfactory and was later 

 employed to the exclusion of the former. 



Up to this point, the two subjects adapted themselves to the 

 different situations with almost equal rapidity. Number 4 was 

 somewhat less willing to try new things than number 3, and 

 seemed to be hampered by its shyness. 



