The contrast-response of the periphery effect.

This report examines the effect of varying the contrast of a flickering remote surround on thresholds for flicker detection, and color detection in rapidly flickering red and green foveal test targets, presented on a steady white background. Flicker in the surround reduced flicker sensitivity for the foveal test stimuli and yielded a periphery effect (PE), whereas it had no effect on color sensitivity (no PE). The magnitude of the PE increased non-linearly as a function of increasing surround flicker contrast. Much of the increase took place at low contrasts (< 0.20) and half-saturation of the PE occurred at 0.16 and 0.29 contrast for the red and green targets, respectively.