Abstract
The rate of microsaccades, small eye movements that occur spontaneously during visual fixation, rapidly drops following the onset of transient stimuli. Here, we demonstrate that this involuntary reflex is yoked to fluctuations in explicit visual perception. Human observers reported the presence or absence of a brief visual stimulus while we recorded microsaccades, small spontaneous eye movements. Microsaccades were reflexively inhibited if and only if the observer reported seeing the stimulus, even when none was present. Moreover, perceptual sensitivity and the oculomotor reflex were both susceptible to orientation-specific adaptation, a signature of cortical processing. The oculomotor reflex therefore tracked perceptual visibility even when the stimulus was physically unchanged. By applying a novel Bayesian classification technique to patterns of microsaccades on individual trials, we were able to decode the state of perception more accurately than the state of the stimulus. We conclude that unified detection mechanisms link perception and oculomotor control: an elemental ‘subjective’ internal event—becoming aware of a change in the environment—is immediately and inadvertently revealed by motor inhibition. By demonstrating an objective measure of conscious detection that does not require explicit reports, this finding opens doors to clinical applications and further investigations of perceptual awareness.
Meeting abstract presented at the 2016 OSA Fall Vision Meeting