THE BEHAVIOR OF THE CROW 189 



For several days previous to the first preliminary series, the 

 crows were compelled to enter the discrimination -chamber in 

 order to get their food. For this purpose the apparatus was 

 placed before a small door in the partition separating the feed- 

 room from the experiment-room. At first, the pan containing 

 the food, was placed just inside the entrance door. Then, grad- 

 ually, it was placed farther back until the crows were required 

 to go through the discrimination-chamber, and the one or the 

 other of the stimulus-chambers, into the exit -boxes. After a 

 few days, they did this with no apparent fear. 



The first preliminary tests were given on July 16th. The 

 crows were then about nine weeks old. The standard stimulus 

 plates had been removed from the stimulus shifter, leaving 

 square openings, 12 cm. by 12 cm. Opal flashed glasses were 

 placed in the slides immediately before these openings, so the 

 illumination of the two chambers was the same. 



The apparatus was adjusted with the entrance-box before the 

 small door in the partition between the feed-room and the ex- 

 periment-room. When one of the crows had entered this box 

 to get the bit of food placed therein, both doors were closed 

 and the entrance-box was then placed before the entrance to 

 the discrimination-chamber. The door leading to the discrimi- 

 nation-chamber next was opened and the crow allowed to enter. 

 The exit doors being open the crow could proceed to one of the 

 exit-boxes and obtain food. The exit and entrance-boxes were 

 now exchanged and the crow given another trial. 



Both crows were much frightened by being confined in the 

 entrance and exit-boxes. After two days, with nine such trials, 

 they became somewhat calmer during the experiments. The 

 exit doors were now closed and the crows allowed to enter the 

 discrimination-chamber, go to one of the stimulus-chambers and 

 there wait until the exit door was opened. This new situation, 

 especially the opening of the exit door, frightened them as much 

 as being shut in the entrance or exit-boxes had at the beginning. 

 In the first trial they could not be induced to enter the discrim- 

 ination-chamber until the exit doors were opened as before. 

 However, after eight trials with the doors closed, they had lost 

 much of their fear. In these seventeen trials, Number 1 went 

 eleven times to the right and six times to the left. Number 2 

 went every time to the right. . 



