Illusory brightness under unconscious processing: Evidence from continuous flash suppression

Brightness perception can diverge sharply from physical luminance due to contextual cues, but whether such illusory brightness is registered without awareness and whether it speeds entry into awareness remain open questions. We used continuous flash suppression (CFS) to test the glare illusion, which increases perceived brightness without changing central luminance. In Experiment 1, we measured breakthrough time (BT) and found no advantage for glare over physically identical controls, indicating that subjective brightness alone does not reliably hasten access to awareness. In Experiment 2, we selectively suppressed the illusion's inducer gradients while leaving the central region visible; here the glare condition showed shorter BTs, suggesting that contextual structure can facilitate detection under suppression. In Experiment 3, participants discriminated both physically brighter stimuli and illusory brightness above chance while the stimuli remained suppressed, demonstrating unconscious processing of brightness information. Together, these findings dissociate unconscious encoding from access to awareness: illusory brightness can be processed without consciousness, yet it does not uniformly accelerate emergence into awareness unless the relevant contextual cues are available to the visual system.