Volume 1
A text-book of experimental psychology : with laboratory exercises / by Charles S. Myers.
- Charles Samuel Myers
- Date:
- 1911
Licence: Public Domain Mark
Credit: A text-book of experimental psychology : with laboratory exercises / by Charles S. Myers. Source: Wellcome Collection.
122/370 page 100
![sensations. According to this view, the more peripheral white-black apparatus, in the absence of the central white- black apparatus, is able to produce only black or white, never grey. The so-called intrinsic light of the retina, Muller urged, is really of central origin due to the activity of the central apparatus. This hypothesis is supported by the fact that even in optic atrophy and after extirpation of the eye, the so-called intrinsic light remains. Attempts have been made to hold a position inter¬ mediate between that of Helmholtz and Hering. Bonders supposed that a trichromic (red, green, and violet) system existed at the periphery of the cerebro-retinal apparatus, while a fourfold, red, yellow, green, and blue, process occurred at the centre. Like Muller, Donders assumed that a single peripheral process might act on more than one central process. Similarly von Kries, while advocating a trichromic process, suggests that at the periphery of the retina a four-colour process is also involved. We have already seen, in the case of temperature sen¬ sations, that a theory, which fairly represented the facts of contrast and adaptation, became difficult of acceptance upon the discovery of a differentiation of end organs at the peri¬ phery. Contrast, however, may occur even when, as in taste, the sensations have apparently independent structural bases at the periphery. Hering’s theory of contrast does not, therefore, preclude the elaboration of sensations from sensory elements, which are more primitive than and perhaps different from those advocated in his colour theory. Nay, nothing is more certain than that, in addition to the more peripheral processes, central processes are also involved, in elaborating visual sensations. Rut at present we are power¬ less to separate the one from the other ; we can only speak of changes in one vast unravelled complex,—the cerebro- retinal apparatus.]](https://iiif.wellcomecollection.org/image/b3135984x_0001_0122.jp2/full/800%2C/0/default.jpg)
