TY - JOUR T1 - Attention to Bright Surfaces Enhances the Pupillary Light Reflex JF - The Journal of Neuroscience JO - J. Neurosci. SP - 2199 LP - 2204 DO - 10.1523/JNEUROSCI.3440-12.2013 VL - 33 IS - 5 AU - Paola Binda AU - Maria Pereverzeva AU - Scott O. Murray Y1 - 2013/01/30 UR - http://www.jneurosci.org/content/33/5/2199.abstract N2 - One longstanding question is how early in the visual system attention exerts its influence. Here we show that an effect of attention can be measured at the earliest possible stage of visual information processing, as a change in the optics of the eye. We tested human subjects and found that covertly attending to bright surfaces results in an enhanced pupillary light reflex (PLR)—the pupillary constriction that occurs in response to light increments. The PLR optimizes the optical quality of the retinal image across illumination conditions, increasing sensitivity by modulating retinal illumination, and improving acuity by reducing spherical aberrations. The attentional modulation of the PLR that we describe constitutes a new mechanism through which vision is affected by attention; we discuss three alternatives for the neural substrates of this effect, including the possibility that attention might act indirectly, via its well established effects in early visual cortex. ER -