Common mechanisms of visual imagery and perception.

Detection of a visual target can be facilitated by flanking visual masks. A similar enhancement in detection thresholds was obtained when observers imagined the previously perceived masks. Imagery-induced facilitation was detected for as long as 5 minutes after observation of the masks by the targeted eye. These results indicated the existence of a low-level (monocular) memory that stores the sensory trace for several minutes and enables reactivation of early representations by higher processes. This memory, with its iconic nature, may subserve the interface between mental images and percepts.