Watson, Color Vision in Monkeys. 19 



as in J's case. The same is true of the early records of another 

 monkey (S). My notes are full of such comments as the following: 

 "Animal apparently is not stimulated by red," "apparently can 

 not see in red light," etc. While I can give no explanation of the 

 results, it is worth while to mention that they are suggestive either 

 of a 'preference' for green, or possibly, in the light of Yerkes' experi- 

 ments on the dancei', of the low stimulating effect of red, I am 

 inclined to favor the first of the two possibilities, if any, for the 

 reason that after the habit of reacting to the red was perfected, the 

 discrimination could still be made when the absolute intensity of 

 the two bands was enormously lessened (I had abundant incidental 

 opportunity to make many such tests on occasions when the arc 

 momentarily, for one reason or another, failed to give an intense 

 spectrum) , 



2. In the case of all three animals the blue-yeMow discrimination 

 arose more rapidly than the red-green. Indeed, in the case of B,, 

 the habit of reacting to blue was formed with extraordinary rapidity. 

 The question arises as to whether blue was not a 'preferred' color. 

 Again, however, there are no unequivocal data at hand to aid us in 

 reaching a decision for two reasons : 1st, the general question raised 

 above, but not answered, as to whether the wdiole red end of the 

 spectrum does not have a low stimulating effect upon the photo- 

 chemical substances in the retina of these animals. If the blue were 

 more intense, the animal might from the beginning tend to react 

 to the blue and to neglect the yellow ; 2d, the effect of practice. It 

 must not be forgotten that when the animals began upon the blue- 

 yellow test, they had previously had training in the red-green. For 

 this latter reason, no conclusion can be drawn from the present work 

 bearing upon the views sometimes expressed that the yellow-blue 

 photo-chemical process is phylogenetically older than the red-green. 



3a. The onset of position habits in the case of both H. and B. 

 in the red-green test, and in that of J. in the blue-yellow and the 

 constant struggle of the experimenter to keep such position habits 

 from forming are significant Although these animals had been 

 obtaining food for several days with a given color stimulus, we find 

 instead of a steady and rapid increase in the ability to associate 



