52 HAROLD C. BINGHAM 



The characteristics of the chicks' behavior offer a less precise 

 basis for determining the location of the threshold. This type 

 of evidence, however, is practically limited to the observer. 

 It can scarcely be conveyed to the reader. Yet, despite the 

 limitations of such evidence, the fact remains that the observer 

 has a qualitative criterion which he may employ in addition to 

 his quantitative measurements. If both agree he naturally 

 feels more certain of his conclusions. 



The two test sheets presented illustrate two different types of 

 behavior. Test Sheet 1 shows that chick 21 lost no time on 

 entering the discrimination chamber, but went directly in every 

 test to the correct compartment. Test Sheet 2 presents a dif- 

 ferent type of behavior, yet it indicates that chick 16 was dis- 

 criminating between the two stimuli. In the first test the 

 chick was quiet for some time after entering the discrimination 

 box; then it went to the wrong side where it stopped momen- 

 tarily. It then turned to the left, went close to the left electric 

 compartment, hesitated, and entered but turned to the right 

 and came out. Again it looked closely at the wrong (right side) 

 stimulus, turned back to the correct stimulus (left), and escaped. 

 The behavior was somewhat similar in the second test except 

 that in turning away from the wrong stimulus, which was this 

 time at the left, the chick turned its self completely around, 

 counter clockwise, and came up before the correct stimulus. 

 The third test shows that chick 16 made two errors for both of 

 which it w^as punished. In test 9 the chick made two complete 

 turns — one counter clockwise from the correct compartment 

 (left side), and one clockwise turn from the other compartment. 



These two test sheets have been selected with an idea of 

 showing as marked contrast as possible in order to emphasize 

 the importance of the chick's behavior during each test and 

 series. The first shows that chick 21 had no difficulty in choos- 

 ing the proper" stimulus. The second indicates that chick 16 

 was comparing the stimuli and using considerable care in choos- 

 ing, although it made two errors. The choices alone do not 

 indicate as much advancement as the details of the behavior 

 during the choices. These two series cannot be called typical 

 yet they represent fairly well some of the essential principles of 

 behavior in the discrimination problem. 



