Central Adaptation in Mechanisms of Form Vision

PERCEPTION of any visual pattern is subject to three well-known forms of adaptation. In the first place a ‘negative after-image’ is formed which tends to reduce the contrast between the brightnesses of neighbouring areas. Secondly, after more prolonged fixation, peripheral parts of the visual field tend to fade from view in large patches. With a stabilized retinal image, it is well known that a third type of adaptation can occur, in which the whole field fades and reappears intermittently.