Functional effects of colour and motion imagery on conscious perception

Mental imagery is an internal process that resembles perceptual experience without the corresponding external stimulus. Mental imagery has close relations with many cognitive functions, and helps individuals describe the past, present and plan the future. Functional imaging research and studies of brain-damaged patients suggest the mechanisms of imagery and perception have some degree of overlap. Mental imagery is often treated as a general trait-like process. In the current study, different imagery modalities or features, colour and motion imagery, were investigated separately. The binocular rivalry method was utilized here to assess mental imagery of colour and motion, where participants were instructed to report the initial dominance in binocular rivalry after imagining or passively viewing one of the rivalry patterns.Study 1 investigated the functional effects of pure colour imagery and perception. Results of Experiment 1 indicated that perceptual dominance during rivalry was significantly biased by the participants prior colour imagery and perception, but this bias induced by colour imagery was attenuated by background luminance. Experiment 2 found that colour imagery could only prime subsequent rivalry when the imagery and rivalry occurred at the same retinotopic location, indicating that colour imagery was location-specific in retinotopic space.Study 2 tested how motion imagery and motion perception influence subsequent motion rivalry dominance. Experiment 1 found a significant priming effect of motion imagery on subsequent motion rivalry, which was stronger in a condition without background luminance than with. However, unlike the result with colour imagery, motion imagery still significantly facilitated subsequent rivalry in the presence of background luminance. This suggested that uniform luminance had a limited influence on the generation of motion imagery. In Experiment 2, participants viewed a binocular rivalry stimulus after passively viewing a motion stimulus at different contrasts. High-contrast motion led to suppression of that same pattern in the subsequent motion rivalry, but no significant facilitation effect was observed for low-contrast patterns. Results from the two studies jointly revealed some similarities and differences between colour and motion imagery, and suggest that mental imagery is likely to have a heterogeneous multi-feature structure