Color induction in equiluminant flashed stimuli

TL;DR

This study investigates how flashed and static equiluminant stimuli influence color induction, revealing that uniform surrounds produce contrast with optimal effects at 40 ms, and luminance differences are crucial for color assimilation.

Contribution

It extends previous research by examining both flashed and static stimuli with equiluminant conditions, highlighting the role of luminance differences in color induction effects.

Findings

Maximum color contrast at 40 ms for uniform stimuli

Color assimilation observed only in static red-green striped stimuli

Luminance differences are key for inducing color assimilation

Abstract

Color induction is the influence of the surrounding color (inducer) on the perceived color of a central region. There are two different types of color induction: color contrast (the color of the central region shifts away from that of the inducer) and color assimilation (the color shifts towards the color of the inducer). Several studies on these effects used uniform and striped surrounds, reporting color contrast and color assimilation, respectively. Other authors (Kaneko and Murakami, J Vision, 2012) studied color induction using flashed uniform surrounds, reporting that the contrast was higher for shorter flash duration. Extending their work, we present new psychophysical results using both flashed and static (i.e., non-flashed) equiluminant stimuli for both striped and uniform surround. Similarly to them, for uniform surround stimuli we observed color contrast, but we did not obtain the maximum contrast for the shortest (10 ms) flashed stimuli, but for 40 ms. We only observed this maximum contrast for red, green and lime inducers, while for a purple inducer we obtained an asymptotic profile along flash duration. For striped stimuli, we observed color assimilation only for the static (infinite flash duration) red-green surround inducers (red 1st inducer, green 2nd inducer). For the other inducers' configurations, we observed color contrast or no induction. Since other works showed that non-equiluminant striped static stimuli induce color assimilation, our results also suggest that luminance differences could be a key factor to induce it.