COLOR BLINDNESS OF CATS 133 



with it have the same flicker-equivalent, namely 1-2, while the 

 six remaining confusion colors differ very slightly from that 

 number. Other groups of colors differ widely from the flicker 

 values of the stimuli, which agrees once more with the experi- 

 ments with grays. 



The relations of the flicker values of the colors to those of the 

 stimulus colors are shown in Figure 3. 



The cats have been found to confuse each stimulus color with 

 a certain gray on the one hand, and with a group of colors on 

 the other. If we should assume that in each pair of these papers 

 the cat has merely seen that gray once more, we may assign to 



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Figure 3 



the group the brightness value of the gray with which the stimulus 

 color was confused. The gray values are then represented, 

 Figure 4, by the straight horizontal lines, whose positions prob- 

 ably indicate the "brightness equivalents" of the several colors 

 for the cats, in the sense in which Miss Washburn uses that term 

 (pp. 145 and 146). 



The deviations of the curves from the horizontal then indicate 

 how much the several colors may vary, for the human eye, from 

 that gray and yet be indistinguishable from it for the animals. 

 These deviations are large for red and blue, slight for green, and 



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