Reflexive attention can be driven by monocular cues without conscious access to eye of origin information

This study examined whether monocular cues can facilitate reflexive attention in the absence of conscious access to the origin of the cue. Across three experiments, participants viewed brief, task-irrelevant, non-predictive cues, followed by targets presented through a mirror stereoscope. The cue and target were delivered to the same eye (valid trials) or the opposite eye (invalid trials). In Experiment 3 only, the cue was presented binocularly in 25% of trials (the neutral condition). Participants could not reliably discriminate which eye received the stimuli and responded solely to target detection. Reaction times were reliably faster in valid trials than in invalid or neutral trials at a cue-target stimulus-onset asynchrony (SOA) of 100 ms. No cueing effects were observed at shorter or longer SOAs, and no evidence of inhibition of return emerged. These findings suggest that early attentional facilitation can be triggered by eye-specific signals, even when there is no conscious awareness of the cued eye. By demonstrating a temporally selective, eye-based facilitation effect, the present results extend previous work on unconscious attentional modulation. They also suggest that early sensory representations can bias reflexive attentional orienting independently of awareness.