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THE INFLUENCE OF COLOURED LIGHTS ON THE SENSITIVITY OF THE EYE TO VARIOUS REGIONS OF THE SPECTRUM: A STUDY IN RELATION TO THEORIES OF COLOUR VISION
Author(s) -
Roaf H. E.
Publication year - 1927
Publication title -
quarterly journal of experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0370-2901
DOI - 10.1113/expphysiol.1927.sp000435
Subject(s) - optics , sensitivity (control systems) , adaptation (eye) , retina , spectral sensitivity , filter (signal processing) , physics , mathematics , optometry , computer science , computer vision , medicine , wavelength , engineering , electronic engineering
1. The threshold value for light has been used as a measure of the sensitivity of the eye. 2. When any light shines on the retina the sensitivity, even of another part, is decreased considerably to short, but much less to long, wave‐lengths. This is the familiar adaptation phenomenon. 3. When two lights shine on the same part of the retina there is a further decrease in sensitivity which has a peculiar spectral distribution; namely, that long wave‐lengths decrease the sensitivity to all shorter ones, whilst short wave‐lengths have comparatively little effect on longer ones. 4. A region of the retina about 30° to the nasal side of the right eye differs from the fovea ( a ) in the greater degree of light adaptation, so that even the long wave‐lengths are noticeably affected; ( b ) in the sensitivity to longer wave‐lengths being somewhat more affected by short ones, when the two shine on the same region of the retina. 5. The bearing of the above results is discussed in relation to theories of colour vision. It is suggested that the most probable explanation is that colour discrimination is due to colour screens in front of certain of the receptors. 6. The results show why a blue screen is the best to protect the eyes from excessively bright lights. It would be interesting to know to what extent “glare” is particularly due to the longer wave‐lengths. A blue filter on the wind‐screen of a motor‐car will protect the eyes from the direct rays of bright head‐lights, whilst allowing one to see the road past the edge of the filter; thus use may be made of the sensitivity to the light of longer wave‐lengths, which these experiments show are not much affected by exposure to short wave‐lengths.