Factors governing the speed of color adaptation in foveal versus peripheral vision.

Troxler showed that fixated stimuli fade faster in peripheral than in foveal vision. We used a time-varying procedure, to show that peripheral adaptation is faster and more pronounced than foveal adaptation for the three cardinal color modulations that isolate different classes of retinal ganglion cells. We then tested the hypothesis that fixational eye movements control the magnitude and speed of adaptation, by simulating them with intermittent flashes, and attenuating their effects with blurred borders. Psychophysical and electrophysiological results confirmed the eye movement-based hypothesis. By comparing effects across classes of ganglion cells, we found that the effects of eye movements are mediated not only by the increase in size of receptive fields with eccentricity, but also by the sensitivity of different ganglion cells to sharp borders and transient changes in the stimulus. Finally, using the same paradigm with retinal ganglion cells, we show that adaptation parameters do not vary for the three classes of ganglion cells for eccentricities from 2° to 12°, in the absence of eye movement.