A STUDY OF COLOR VISION IN THE RING-DOVE 41 



readily distinguished by certain individuals and with difficulty 

 by others. The particular results in hand suggest that the red 

 has a higher stimulating value for the male than for the female. 



The next step in the experiment would naturally enough 

 have been observation of the responses of the subjects to varied 

 energy values (intensities) of the two chromatic stimuli. Un- 

 fortunately, the investigation had to terminate at the end of 

 May and the laborious preparation for these final observations 

 was unavoidably wasted. The writer had fully expected and 

 hoped, within the period of six months at his disposal when the 

 investigation was undertaken, to ascertain whether the ring- 

 dove can distinguish a red from a green stimulus throughout a 

 wide range of energy or intensity values. This he did not suc- 

 ceed in doing, and consequently this report must be entitled 

 ' Preliminaries to a study of color vision in the ring-dove." 



The principal conclusions w T hich may safely be drawn from 

 these observations have been suggested in the course of the 

 presentation, but by way of summary and review, they may 

 be enumerated here. 



1. It is fairly obvious that the ring-dove is not sufficiently 

 docile to be an ideal subject for the study of color vision by 

 means of the method which Watson and I have developed. 



2. It is indicated that the value of a certain red and a certain 

 green may be very different for two ring-doves, and it is pos- 

 sible that this difference is correlated with sex, the red having 

 a higher stimulating value for the male than for the female. 



3. As has already been demonstrated by the writer in the 

 case of a number of animals, the use of the electric stimulus as 

 a means of compelling attention to an experimental situation 

 and of promoting habit formation is desirable in work with the 

 ring-dove. 



4. Ring-doves differ markedly in temperament. The pair used 

 by the writer throughout this work presented differences which 

 must be considered if one is to understand the results. To 

 begin with, the ♦male was somewhat wild, but at the same time 

 fairly bold, whereas the female was tamer but more timid. Be- 

 cause of this contrast in timidity, the male almost from the 

 start proved the better subject. He was not so easily disturbed 

 or distracted, reacted therefore more steadily, and chose more 

 certainly. With constant handling he became quite as tame as 



