Receptoral and postreceptoral visual processes in recovery from chromatic adaptation.

Abstract

The time course of recovery from chromatic adaptation in human vision was tracked by determining the wavelength of light that appears uniquely yellow (neither red nor green) both before and after exposure to yellowish green and yellowish red adapting lights. Recovery is complete within 5 min after steady light exposure. After exposure to the alternating repeated sequence 10-sec light/b-sec dark, the initial magnitude of the aftereffect is reduced but recovery is retarded. The results are interpreted in terms of two processes located at different levels in the hierarchical organization of the visual system. One is a change in the balance of cone rece tor sensitivities the second is a shift in the equilibrium base~hne between opposite-signed responses of the red/green channel at the opponent-process neural level. The basemine-shift mechanism is effective in the condition in which repeated input signals originating at the receptors are of sufficient strength to activate the system effectively. Hence, this process is revealed in the alternating adaptation condition when the receptors undergo partial recovery after each light exposure, but receptor adaptation during continued steady light exposure effectively protects the subsequent neural systems from continued strong activation.A salient characteristic of the visual system is its adaptability. It adapts to the level of ambient light, which accounts for the broad (orders of magnitude) range of light levels within which useful vision is possible, and also to the spectral weighting of the ambient light, which accounts for the relative stability of the world of colored objects when seen in various artificial and natural conditions of illumination. The changes that occur during light exposure and the recovery to the preexposure state after light stimulation can be assessed for human observers by standard psychophysical techniques appropriate for threshold estimates of visual sensitivity or by suprathreshold measures based on some constant criterion of visual response. Such measurements have shown, in earlier studies, that visual adaptation can be attributed in part to the retinal receptors and their photosensitive pigments which bleach upon absorption of light quanta and regenerate when the flow of incident quanta is diminished (1, 2). However, retinal receptor adaptation alone cannot account for all of the phenomena attendant upon exposure to different levels and spectral distributions of adapting lights. Also implicated are the neural levels (in the retina and possibly also more centrally in the visual system) where excitatory-inhibitory interactions occur, in neural systems that are laterally interrelated, and in temporal rebound or feedback processes (3-6).Our own earlier studies were concerned with relating different steady-state adaptation conditions, whether to different levels of light exposure or to different spectral distributions of adapting light. The study reported here is concerned with the time course of recovery to a neutral equilibrium conditio...

Some effects of 1 week’s monocular exposure to long-wavelength stimuli

“…Benzchawel & Guth, in press;Eisner & MacLeod, 1981;Finkelstein & Hood, 1981;Jameson, Hurvich, & Varner, 1979;Pugh & Mollon, 1979;Stabell & Stabell, 1975;Stromeyer & Sternheim, 1981;Valeton & van Norren, 1979;Wandell & Pugh, 1980). Stabell and Stabell found scotopic color contrast effects after short-term (lO-sec) chromatic adaptation, although they did not explicitly discuss the locus of the effects, and Jameson et al found changes in unique yellow lasting several minutes which they ascribed to postreceptoral opponent color processes after intermittently (10 sec on, 10 sec off) adapting the eye to colored stimuli for 5 min.…”

Adaptation from invisible flicker

“…The attenuation of human flicker sensitivity, consequent to adaptation, is evident in both behavioral (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) and neural (9,23,24) response measures, but its frequency dependence has never been assessed systematically. Here we measure the reduction in flicker sensitivity after prolonged exposure, or adaptation, to both luminance and chromatic flicker across a wide range of frequencies.…”

“…Here we pursue these questions through an experimental design that exploits, as a functional landmark, the known process of flicker adaptation, by which flicker sensitivity of an observer is attenuated after prolonged exposure to flickering lights (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22). The attenuation of human flicker sensitivity, consequent to adaptation, is evident in both behavioral (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) and neural (9,23,24) response measures, but its frequency dependence has never been assessed systematically.…”

The indirect McCollough effect: An examination of an associative account

“…The results of Jameson et al (1979), Hansel and Mahmud (1978), and Mahmud (1987) all suggest that the aftereffects observed on the homogeneous fields are not contingent aftereffects. This suggestion is certainly consistent with our findings in Experiment 3.…”

“…One possible account for this effect is that there is some overall shift in color balance that is not very closely tied to, or dependent on, a match between retinal contours in induction and test; in short, it is not a contingent aftereffect. Research by Jameson, Hurvich, and Varner (1979) suggests such a possibility. They found that viewing a colored light source alternating with a blank field produced a shift in perceived color that persisted for at least 15 min (no measurements were made beyond 15 min).…”