On the limitation of physical methods in the investigation of the physiological and psychical phenomena of sight / by F.W. Edridge-Green.

  • Edridge-Green, F. W. (Frederick William), 1863-1953.
Date:
[1900]
Catalogue details

Licence: In copyright

Credit: On the limitation of physical methods in the investigation of the physiological and psychical phenomena of sight / by F.W. Edridge-Green. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    person's vision is still hexachromic when he looks through a pale yellow glass. Hyperesthesia to certain colours.—Another source of error in matching colours with white light is that persons differ as to their sensibility to all colours or to certain of them just as they differ in their physiological actions in other parts of the body. One person can read in a very feeble light but is dazzled by a light which to another person is quite comfort- able. A person of this kind matches a red with a grey which is much darker than that chosen by another person, though both may have equally good colour perception. Again, men vary as to their sensibility to certain colours; one is more affected by red, another by green, and another by yellow. We can also have temporary hyperesthesia, an exaggerated example of which is found in photophobia. Idea as to comparative luminosity.—Tn matching colours with white light or with each other much depends upon the observer's idea of the colour. If I make a match of red and grey with the idea that red is a very bright colour I shall make a match with a much lighter grey than I should if I had the idea that red was a very dark colour. If the theory as to a photo-chemical substance be admitted then the action of light on the substance may produce an excessive reaction with one person and very little with another ; the apparent luminosity would be much greater in the first case. The secretion of fresh photo-chemical substance may be quicker in one person than in another. We know that the visual purple may be bleached by mono- chromatic as well as by mixed light. If we suppose the visual substance of the eye to be decomposed in the same manner it would be possible to understand that we might get similar curves of luminosity by different colours though the visual impulses sent to the brain might in each case be different. If there be, and all recent research points to the fact that there are, different centres in the brain for the perception of luminosity and colour it is obvious that ascertaining the luminosity of a colour' will not give us any information concerning that colour because the two are absolutely and totally distinct. In order to make my meaning clearer I will make a com- narison with the organ of hearing. The perception of pitch is in every respect analogous to the perception of colour and