1 16 



M. F. WASHBURN AND FDWINA ABBOTT 



1.00 

 .90 

 .80 

 .70 

 • 60 



.40 

 .30 



.20 

 .10 



case that the animal teste, 1 can learn to discriminate a color, 

 not merely from the gray of equal brightness to the human 

 eye, bu1 from every one of a series of brightnesses ranging from 

 black to white, then we shall have ground for inferring that the 

 color is indeed seen as a color and not as a gray. 



Our problem in the present research was to find, if possible, 

 the equivalent brightness for red to the light-adapted eye of the 

 rabbit. We chose red, because the results of Yerkes and Watson 

 have indicated that the brightness value of this color is probably 



•30 .32 .34 .36 .38 .40 .42 .44 .46 .48 .50 .52 .54 .56 .58 -60 



.64 .66 .68 .70 h- 



Figure 1. Color values of Bradley papers. Curve A, blue; Curve B, red; Curve 

 C, "darkened" red. 



different and markedly less for the eye of the dancing mouse and 

 the monkey than for the eye of man. We also made some series 

 of experiments to investigate the brightness value of blue, with 

 less conclusive results. 



Our work was done with the Bradley colored papers and the 

 Hering gray papers: we also used a "black" paper supplied by 

 the C. H. Stoelting Company, of a brightness more nearly equiv- 

 alent to that of Hering gray number 46 than to any of the other 

 Hering papers. While it is desirable that all final work on color 

 discrimination in animals be done with pure spectral colors, yet 

 as the apparatus for the use of such colors as stimuli is compli- 



