SECTION IV 



THE OPPONENT COLOURS THEORY (HERING) 



CHAPTER I 



STATEMENT OF THE THEORY 



The three-components theory approaches the subject from what I 

 have called the synthetic point of view. It provides a theory of colour 

 sensations in terms of stimulus intensities. The opponent colours 

 theory approaches the subject from the analytic point of view and 

 provides a theory in terms of visual sensations. 



Mach^ had already pointed out in 1865 that the black-white series 

 of sensations differed fundamentally from the chromatic series. On 

 the principle of psychophysical parallelism the two series should have 

 different physiological bases. Hering^ adopted the psychological 

 analysis of Goethe, Mach and others, that red, yellow, green, and blue 

 were the only simple and unmixed colour-sensations, but advanced 

 novel views about black. He adopted the view generally accepted by 

 psychologists^ that black is a sensation and is not the expression of the 

 mere absence of stimulation^. The completely dark-adapted eye when 

 sheltered from all external stimuli gives a sensation which is variously 

 described as the hght chaos, the intrinsic light of the retina, and so on. 

 Hering called this sensation " mean grey." According to him " black " 

 occurs only as the result of external stimulation, i.e., under the influence 

 of simultaneous or successive contrast. The " black '" of a black patch 

 seen on a white background, or of the after-image of a white patch, is 

 blacker than the intrinsic light of the eye and is regarded by Hering as 

 the true black sensation. 



1 Sitz. d. Wiener AJcad. Ln. 2. 320, 1865. * Zur Lehre vom Lichtsinne, 1876. 



3 Cf., however, Ward, Brit. .11. of Psychol, i. 407, 1905. 



* Contrast Leonardo da Vinci — " L' ombra e diminuzione di luce, tenebre fe privazione 

 di luce." Trattato delta Pittura, ed. 1817, Rome, p. 274. 



