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

doi:10.1073/pnas.0707727105

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

*Division of Biology, California Institute of Technology, Pasadena, CA 91125;
^†Institute of Computational Science, ETH Zentrum, CAB G 81 Universitätstrasse, CH-8092 Zurich, Switzerland;
^‡Vision Sciences Laboratory, Harvard University, 33 Kirkland Street, Cambridge, MA 02138; and
^§Brain Research Institute, Waterdale Road Heidelberg West, Victoria 3081, Australia

Edited by Dale Purves, Duke University Medical Center, Durham, NC, and approved December 18, 2007 (received for review August 16, 2007)

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.

Footnotes

^¶To whom correspondence should be addressed. E-mail: ocarter{at}wjh.harvard.edu
Author contributions: W.E. and O.C. designed research; W.E., J.S., and C.K. performed research; C.K. contributed new reagents/analytic tools; W.E. analyzed data; and W.E. and O.C. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/cgi/content/full/0707727105/DC1.