COLOR CONTRASTS, 525 



secure their greatest effect depends on this fact; red and 

 green go well together because each rests the parts of the 

 visual apparatus most excited by the other, and so each 

 appears bright and vivid as the eye wanders to and fro; 

 while red and orange together, each exciting and exhaust- 

 ing mainly the same visual elements, render dull, or in 

 popular phrase "kill," one another. 



Contrasts. If a well-defined black surface be looked at on 

 a larger white one the parts of the latter close to the black 

 look whiter than the rest, and the parts of the black near 

 the white blacker than the rest; so, also, if a green patch be 

 looked at on a red surface each color is heightened near 

 where they meet. This phenomenon is largely due to fatigue 

 and deficient fixation: a region of the eye rested by the 

 black or the green is brought by a movement of the organ 

 so as to receive light from the white or red surface; phe- 

 nomena due to this cause are known as those of successive 

 contrast. Even in the case of perfect fixation, however, 

 something of the same kind is seen; black looks blacker 

 near white, and green greener near red when the eye has not 

 moved in the least from one to the other. A small piece of 

 light gray paper put on a sheet of red, which latter is 

 then covered accurately with a sheet of semi-transparent 

 tissue-paper, assumes the complementary color of the red, 

 i.e. looks bluish green; and gray on a green sheet under 

 similar circumstances looks pink. Such phenomena are 

 known as those of simultaneous contrast, and are explained 

 on psychological grounds by those who accept Young's 

 theory of color vision. Just as a medium-sized man looks 

 short beside a tall one, so, it is said, a black surface looks 

 blacker near a white one, or a gray (slightly luminous 

 white) surface, which feebly excites red, green, and violet 

 sensations, looks deficient in red (and so bluish green) 

 near a deeper red surface. There are, however, certain 

 phenomena of simultaneous contrast which cannot be satis- 

 factorily so explained, and these have led to other theories 

 of color vision, the most important of which is that de- 

 scribed in the next paragraph. 



Hering's Theory of Vision. Contrasts can be seen with 



