Abstract
Color constancy refers to our ability to distinguish changes in surface properties from changes in the light illuminating the scene, or of a filter through which the scene is viewed. The apparent ease with which we can tell that objects do not change color, e.g. when moving from sunlight to the shade, belies the complexity of solving this ill-constrained problem. Although there is a substantial body of work testing which image cues might be used to accomplish this, there is surprisingly little known of how the brain performs this computation. Here, we tested a fundamental aspect of this perceptual process: whether it requires attention. We performed two experiments, testing visual search times and discrimination ability for both surface color (requiring scission of surface and illuminant/filter properties) and raw color (which does not). We found a clear difference between the two: visual search for raw color was fast and parallel, while search for surface color was slow, requiring serial deployment of attention. Discrimination performance suggested that although raw color detection is fast and parallel, once attention is directed to the stimulus and perceptual scission occurs, raw color information is discarded. Together, these results offer new insights into the neural processes associated with color constancy.