Minimal required exposures reveal the primacy of awareness in human face perception

Abstract

AbstractThe human visual system is capable of detecting extremely small light signals, as little as one single photon. But what is the visual system’s minimal exposure threshold to detect meaningful stimuli? Due to hardware limitations, studies examining fast visual processing typically present stimuli for suprathreshold durations and disrupt processing with a mask. Here, we employed a newly developed tachistoscope that enables sub-millisecond presentations. Combining measures of perceptual sensitivity and recordings of neural activity, we find that both the holistic configuration and the emotional expression of a human face have the same minimal required exposure as the minimal required exposure for faces to reach awareness. These findings indicate that conscious awareness is required for processing meaningful visual information.