170 M. I WASUBCKN AND EDW1NA ABBOTT 



of 76 experiments by Abednego (Series 25). There is some 

 evidence that grey number 1 5 looks darker than saturated blue : 

 Dark Nose showed a marked tendency to choose grey 15 rather 

 than blue in tests interpolated among red and grey tests where 

 she was choosing the red, that is, the darker impression (Series 

 17); Abednego showed a tendency to choose grey 15 rather than 

 blue in a series of 20 experiments following on a long experience 

 of choosing the darker impression (Series 24). There was some 

 evidence that saturated blue can be discriminated from the very 

 light, almost white, Hering grey number 2, whether through 

 brightness or color difference (Series 26). On the whole, it is 

 suggested by our results that the brightness equivalent of satu- 

 rated blue is in the neighborhood of Hering grey number 7, that 

 is, decidedly lighter than would be the case for the human eye. 

 It is interesting to note that one of Breed's chicks, which pre- 

 ferred white to black and yellow to black, preferred Bradley 

 saturated blue to a yellow which was " very light, much brighter 

 than the comparatively dark blue, not only as judged directly 

 by the human eye, but as tested by the flicker method." 6 



On the other hand, the rabbit Shadrach, in next to the longest 

 single series of tests made, showed some evidence that he was 

 learning to discriminate saturated blue from grey number 7 

 (Series 29). If the discrimination was being acquired, it may 

 have been based on a very slight brightness difference, or on a 

 color difference. 



6. When discrimination became difficult for the rabbits they 

 fell back upon a habit of always choosing the door on one side 

 of the box. Out of 39 instances where such a habit was recorded, 

 it was a left-hand habit in 9 cases only, and in all these left- 

 hand cases the habit persisted for one day only, while a right- 

 hand habit often appeared for several successive days. 



7. The rabbits did not acquire a habit, based on kinaesthetic 

 data, of alternating from side to side in their choices, but were 

 throughout guided by visual clues. This is shown by several 

 facts. 



a) No matter how regularly they had been choosing red in 

 red-grey series where the red was on either side alternately, the 

 red habit immediatelv broke down when black was substituted 



6 Breed, F. 8. The Development of Certain Instincts and Habits in Chicks. 

 Behavior Monographs, vol. I, no. 1. 1911. 



