VISUAL PERCEPTION OF THE CHICK 61 



work out of this subject, and at the same time, called forth less 

 energy than in the earlier tests. No. 21 knew me quite well by 

 this time. It was perfectly contented to leave its companions 

 in the chick-room and 'go alone with me to the dark-room for 

 work. The chief reason for this was the fact that it always had 

 its morning feeding in the dark-room. As soon as we reached 

 the experiment room it was given a little chick food and allowed 

 to run freely about until the apparatus was made ready for the 

 tests. During the preparation of the apparatus, the chick 

 would follow me about the room (then lighted) twittering and 

 contented, but if it were left alone for a few minutes its dis- 

 satisfaction was made known by loud and ceaseless peeping. 



When everything was ready the chick was placed in the ap- 

 paratus. At this point the note in its voice changed to a slightly 

 modified "hovering twitter." Commonly this peculiar sort of 

 "singing" changed, as the chick entered the discrimination 

 chamber, to the "food twitter" which was continued all the 

 time it was inspecting and comparing the two stimulus areas 

 and, of course, after it had entered the nest box, for there it 

 was rewarded by finding a few grains scattered in the litter. 

 In this manner a series could be completed in about fifteen 

 minutes, after which the chick was taken from the experiment 

 box and given more food and its freedom in the room. This 

 procedure could be carried out until the chick's hunger was 

 satisfied after which the tests went so slowly and with such 

 uncertainity that it was found best to postpone the work until 

 the following morning. As the bird became older this mode of 

 experimentation could be carried on as long as three hours. 



While I was preparing test sheets or making notes at my 

 desk between experiments, No. 21 would crowd about my feet 

 and "beg" to be taken up. If it were allowed to perch itself 

 on my arm it would sit there as long as I was quiet, contentedly 

 preening its feathers and occasionally giving a short "hovering 

 twitter." All of this indicates that the chick was quite con- 

 tented and normal throughout the experiment. 



Table 7 shows the results of my first study of form with chick 

 21 in which it was trained to go to the triangle and to reject the 

 circle or square. While none of the results here recorded are 

 clear cut, there is strong evidence that the chick was discrimi- 

 nating between the two stimuli. This experiment was hurried 



