Motion Influences the Effects of Systematic Chromatic Changes

One example of color constancy is color transparency: when a surface is seen both in plain view and through a transparent overlay, the visual system still identifies it as a single surface. Previous studies suggest that color changes across a region of an image that can be described as translations and/or convergences in a linear trichromatic color space lead to the perception of transparency, but other transformations, such as shear and rotation, do not. Recently, other studies have added motion to their stimuli, claiming that this enhances the transparency effect. We tested whether complex configurations and motion are neutral with respect to the effects of systematic color changes. We defined several experimental conditions: a static versus moving stimulus condition, a simple (bipartite stimuli) versus a more complex configuration (checkerboard stimuli), equiluminant, filter and illumination overlay conditions. Different absolute color changes (vector lengths) were also chosen and varied systematically within the gamut of the monitor. The main results show that motion influences observers' responses for translations independently of stimulus complexity, luminance conditions, and vector lengths. A strong effect is observed for divergences that induce transparency perception in moving checkerboard conditions. However, while shears in a moving bipartite configuration tend to be transparent, this effect is completely cancelled for checkerboard like stimuli, even in motion. Finally, neither motion nor complex configuration effects have been found for convergences.