Pupil dilation reflects perceptual selection and predicts subsequent stability in perceptual rivalry

TLDR

During sustained viewing of an ambiguous stimulus, an individual's perceptual experience will generally switch between the different possible alternatives rather than stay fixed on one interpretation (perceptual rivalry). Here, we measured pupil diameter while subjects viewed different ambiguous visual and auditory stimuli. Across all stimuli, pupil diameter rose just before a perceptual switch and the magnitude of this dilation predicted the ensuing period of perceptual stability, a relationship that cannot be attributed to blinks, eye movements, motor responses, or retinal input changes, and suggests that locus coeruleus–norepinephrine activity may influence perceptual selection similarly to its role in decision making.

Abstract

During sustained viewing of an ambiguous stimulus, an individual's perceptual experience will generally switch between the different possible alternatives rather than stay fixed on one interpretation (perceptual rivalry). Here, we measured pupil diameter while subjects viewed different ambiguous visual and auditory stimuli. For all stimuli tested, pupil diameter increased just before the reported perceptual switch and the relative amount of dilation before this switch was a significant predictor of the subsequent duration of perceptual stability. These results could not be explained by blink or eye-movement effects, the motor response or stimulus driven changes in retinal input. Because pupil dilation reflects levels of norepinephrine (NE) released from the locus coeruleus (LC), we interpret these results as suggestive that the LC–NE complex may play the same role in perceptual selection as in behavioral decision making.