182 H. M. JOHNSON 



The tendency of Chick 2 to respond by choosing or rejecting 

 the familiar stimulus differs from the behavior of some birds 

 used by Bingham, 5 which chose the larger of two circles and 

 avoided the smaller without regard to the absolute size of the 

 larger, and without regard to its previous association with re- 

 ward or punishment. The comparison is worthy of mention as 

 it seemingly points to an individual difference. 6 Bingham, how- 

 ever, gives no details which indicate how nearly unanimous or 

 how consistent his birds were in manifesting this form of behavior. 



AN INCIDENTAL OBSERVATION 



One incidental feature of the behavior of Monkey 2 seems 

 deserving of special mention. As was remarked above, I used 

 a plate glass partition across the entrances of Alleys A 1 and A 2 

 of the Yerkes box. This partition contained two rather small 

 holes through which the animal had to squeeze himself in order 

 to enter the alley. On two occasions — June 16, 1914, and 

 March 14, 1915, I neglected to insert this partition before giving 

 the first trial of the daily series. On each occasion the animal 

 refused to enter either alley. When I looked into the box to 

 ascertain the cause of his delay in responding I found him grop- 

 ing in large semi-circles with his hands near the plane in which 

 the glass partition belonged, and uttering frequent vocal excla- 

 mations. It was necessary to recall him to the home-com- 

 partment and insert the partition. It appeared from this be- 

 havior that he had become habituated to disregarding the par- 

 tition as a visual object. 



RELATIVE EASE OF DISCRIMINATION 



In tables 4 and 5 I have summarized the values taken as 

 "thresholds" for the two animals. The reader may see how 

 these values were obtained by referring to tables 1 and 2, in 

 which the animals' daily records appear. Whenever there 



6 Bingham, H. C. Size and form perception in Gallns domesticus. This journal, 

 vol. 3, 1913, pp. 65 ff. 



6 Watson (Behavior p. 367) refers to the difference between the behavior of 

 my chick and those of Bingham's as indicating that " this (Bingham's) observa- 

 tion cannot be confirmed." This interpretation is not mine. Had all the birds 

 been worked on the same problem I should not have considered that the behavior 

 of one bird was predictable from the behavior of a few others. But the two prob- 

 lems are so different that there is little basis for comparison. 



