Abstract
Using metacontrast, we looked at target suppression and target recovery under binocular and dichoptic viewing of stimuli, with the ability to additionally introduce binocularly rivalry suppression in the latter viewing condition. Our investigations revealed the following functional hierarchy of unconsciously processing of visual stimuli: 1) Studies of masked priming showed that a target form can be processed unconsciously at levels that already have extracted, at minimum, conjunctions of primitive orientation features such as corners and vertices. 2) Studies of target recovery, produced by using a secondary mask to weaken the masking effect of the primary mask, showed that recovery is absent or greatly reduced under dichoptic presentation of the two masks, indicating that target recovery occurs primarily at unconscious levels prior to cortical binocular activation. 3) Studies of target recovery, produced by binocular rivalry suppression of the mask, showed that the cortical mechanism responsible for metacontrast suppression, itself activated at unconscious levels of cortical processing, occurs after the cortical level of binocularly rivalry suppression. Besides allowing us to establish functional hierarchies of unconscious processing in the cortical visual system, these results also allow us to distinguish between current models of target masking and recovery.
Supported by NSF grant BCS-0114533 and NIH grant R01-MH49892.