The relation of light perception to colour perception / by F.W. Edridge-Green.

  • Edridge-Green, F. W. (Frederick William), 1863-1953.
Date:
1910
Catalogue details

Licence: In copyright

Credit: The relation of light perception to colour perception / by F.W. Edridge-Green. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    X 5877. Nos. 2 and 3 have a spectrum of normal length and of exactly the same size, whilst 1 has a spectrum which is shortened at both ends but more shortened on the red side. The centre of the smallest patch of 1 is X 5543 and the centres of 2 and 3 X 5306 and X 5174 respectively. It would appeal as if these were three similar cases with different absorption. We know that the portions of the spectrum which differ are those which are most influenced by the varying pigmentation of the yellow spot. It will be noticed that the total effect is the same, the spectrum being divided into 10 patches in each case, so that what is gained on one side is lost on the other. No. 2 is the spectrum of Sir J. J. Thomson, further details of whose colour perception I have given in the f Proceedings of the Royal Society,’ B vol. 76, 1905, p. 194. Sir J. J. Thomson, when making the match previously mentioned with Rayleigh’s apparatus, put more green than the normal in the mixed colour, but the other two triehromics made the normal match. It if obvious that this alteration in light perception could not produce the defect in colour perception which was found. By the use of the spectrometer described above, it is easy to detect cases of defective colour perception of a smaller degree than the two classes I have just described. In fact, if we regard the normal individual as hexachromic, we can differentiate classes possessing five and four colour sensations respectively, which may be called pentachromic and tetrachromic. In these cases, the only loss is the power of differentiation of hue. The sensibility to light, i.e. to luminosity, may be normal throughout the whole spectrum. These minor cases will, as a rule, match wools perfectly, but may make slight mistakes when asked to name the colours of single skeins. The pentachromic may be regarded as differentiating the colours red, yellow, green, blue, violet, while the tetrachromic would name only the colours red, yellow, green, violet. It is evident that none of these classes can be explained by assuming the absence of any substance or set of percipient elements sensitive to light over a considerable area of the spectrum. Any theory of colour vision must explain the position of the colours and the varying size of the monochromatic patches in each case. IIakrison and Sons, Printers in Ordinary to His late Majesty, St. Martin’s Lane.