SECTION TV 



THE OPPONENT COLOURS THEORY (BERING) 



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 1 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 2 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 3 that black is a sensation and is not the expression of the 

 mere absence of stimulation 4 . The completely dark-adapted eye when 

 sheltered from all external stimuli gives a sensation which is variously 

 described as the light 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 Akad. in. 2, 320, 1865. 2 Zur Lehre vom Lichtsinne, 187G. 



3 Cf., however, Weird, Brit. Jl. of Psychol. I. 407, 1905. 



4 Contrast Leonardo da Vinci " L' ombra e diminuzione di luce, tenebre privazione 

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



