Reflexive attention can be dissociated from consciousness: Behavioral evidence from monocular stimulation

In this study, we examined whether monocular cues could direct exogenous attention without awareness of the eye of origin. Across three experiments, participants viewed brief, task-irrelevant, non-predictive cues and subsequent targets through a mirror stereoscope. The cue and target were presented to the same eye (valid trials), to the other eye (invalid trials), or to both eyes (neutral condition). Participants were unaware of which eye received each stimulus and responded only to the presence of the target. We found that reaction times were consistently faster in valid trials than in invalid or neutral trials at the 100 ms cue–target SOA. No cueing effects appeared at either shorter or longer intervals, and no evidence of inhibition of return was observed. These findings suggest that attentional selection can operate on monocular representations without conscious awareness of the cued eye. Our results complement previous evidence from interocular suppression and unconscious priming, indicating that the visual system can prioritize early sensory input independently of awareness. This supports models that propose distinct mechanisms for attention and consciousness. We conclude that eye-of-origin information, though inaccessible to introspection, is sufficient to trigger reflexive attentional orienting and enhance behavioral responses.