The functional effects of color perception and color imagery

Functional imaging research and studies of brain-damaged patients suggest the mechanisms of color perception and color imagery have some degree of overlap. Previous research into color imagery has focused on compound images consisting of both color and form, e.g., whole objects. Little is known regarding the characteristics of pure color imagery-color without form structure. Binocular rivalry has proven to be a successful method for assessing mental imagery indirectly, quantitatively, and reliably. Here, we utilized this technique to access pure color imagery. Experiment 1 consisted of three conditions, in which participants were instructed to either imagine pure colors according to a letter cue, imagine pure colors in the presence of background luminance, or passively view weak perceptual color patches. Subsequently, a brief rivalry display was presented. Results indicated that perceptual dominance during rivalry was significantly biased by the participants' prior color imagery and perception. However, for imagery, the addition of background luminance attenuated this priming effect. In Experiment 2, we tested whether color imagery was location-specific in retinotopic space. Color imagery was only found to prime subsequent rivalry when the imagery and rivalry stimuli occurred at the same retinotopic location. These results demonstrate that imagery of pure colors without form structure can influence subsequent color perception and can be localized in retinotopic space. These results are consistent with previous studies examining mental imagery of compound visual stimuli and demonstrate the potential of investigations into mental imagery of individual visual features.