Note of a method of studying the binocular vision of colour / by John G. M'Kendrick, M.D.

  • McKendrick, John G. (John Gray), 1841-1926.
Date:
[1877?]
Catalogue details

Licence: Public Domain Mark

Credit: Note of a method of studying the binocular vision of colour / by John G. M'Kendrick, M.D. 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.

    6/8 (page 656)
    paper rendered translucent by oil, &c. In showing the experiment to others, I have found that certain people do not see the resultant colour, whilst others do so readily. The cause of this and of the opposite statements of the observers above alluded to, I believe to be this : The sensation resulting from the fusion in the brain of the two impressions, one coming from each eye, appears to be capable of decomposition by a mental effort. Thus, the purple produced by red and blue appears as such to my eye so long as I simply look at it without any conscious effort; but if I wish to analyse it, I then find that the two colours, red and blue, seem to be superposed on each other, and the one appears to shine through the other. On ceasing to make any effort, they again fuse together as before. Again, by thinking of the colour opposite the right eye, say red, the field ceases to be purple and has a decided tinge of red, and on thinking of the colour before the left eye, say blue, the prevailing tone of the field is blue. Apparently, then, if corresponding points of two retinae be simultaneously stimulated by two different colours, the impressions are fused in consciousness into the resultant colour ; but the resulting sensation may be decomposed by an act of atten- tion. The decomposition is effected partly by strongly directing the attention to one eye, and less strongly to the other, and the result is a sensation corresponding to the colour placed before the eye to which the attention is most strongly directed. Some of the same facts may be studied with the aid of the stereoscope.