Researchers (IMAGE) University of Pennsylvania School of Medicine Caption This image depicts Geoffrey K. Aguirre, MD, PhD, a behavioral neurologist and associate professor in the department of Neurology; Manuel Spitschan, a Penn graduate student in psychology; and David Brainard, PhD, RRL professor of Psychology, director of the Vision Research Center and director of the Institute for Research in Cognitive Science; found that melanopsin, a protein and short wave-sensitive S-cones, both in the retina, have opposite effects and compete for control of the pupil in response to blue light. Credit Aguirre, Spitschan, Brainard Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.