1 66 The Dancing Mouse 



indicated the all-important role of brightness vision that I 

 have hesitated to interpret any of them as indicative of true 

 color discrimination. But after I had made all the varia- 

 tions in brightness by which it seemed reasonable to suppose 

 that the mouse would be influenced under ordinary condi- 

 tions, and after I had introduced all the check tests which 

 seemed worth while, there still remained so large a proportion 

 of correct choices that I was forced to admit the influence of 

 the quality as well as of the intensity of the visual stimulus. 



The first of the facts mentioned above, that brightness 

 discrimination is more important in the life of the mouse 

 than color discrimination, is attested by almost all of the 

 experiments whose results have been reported. The second 

 fact, namely, that the dancer possesses something which for 

 the present we may call red^green vision, also has been 

 proved in a fairly satisfactory manner by both the reflected 

 and the transmitted light experiments. I wish now to pre- 

 sent, in Table 26, results which strikingly prove the truth of the 

 statement that red appears darker to the dancer than to us. 



The brightness conditions which appeared to make the 

 discrimination between green and red most difficult were, so 

 far as my experiments permit the measurement thereof, green 

 from i to 4 candle meters with red from 1200 to 1600. 

 Under these conditions the red appeared extremely bright, 

 the green very dark, to the human subject. 



According to the description of conditions in Table 26, 

 Nos. 2 and 5 were required to distinguish green from red 

 with the former about 3 candle meters in brightness and the 

 latter about 1800 candle meters. In the eighth series of 20 

 tests, each of these animals made a perfect record. As it 

 seemed possible that they had learned to go to the darker 

 of the two boxes instead of to the green box, I arranged the 

 following check test. The filters were removed, the illumi- 



