The Department of Cognitive Sciences Colloquium Series presents

"Economic Motion Sensing"
with Sergei Gepshtein, Ph.D., Staff Scientist, The Salk Institute for Biological Studies, La Jolla, California

Wednesday, January 9, 2013
12:00 p.m.
Social & Behavioral Sciences Gateway (SBSG), Room 1517

A basic tenet of sensory biology is that sensory systems adapt to the environment. For example, visual adaptation is expected to improve visual performance in the new environment. The expectation has been contradicted by evidence that adaptation sometimes decreases visual sensitivity for the adapting stimuli, and sometimes it changes sensitivity for stimuli very different from the adapting ones. Gepshtein argues that this pattern of results can be explained by a process that optimizes sensitivity for many stimuli, rather than changing sensitivity only for the stimuli whose statistics have changed. In his talk, he will describe a series of experiments in which visual contrast sensitivity was measured across a broad range of stimuli, while varying the distribution of stimulus statistics. The manipulation of stimulus statistics caused a large-scale reorganization of contrast sensitivity, forming the orderly pattern of gains and losses of sensitivity. This pattern is predicted by a theory of efficient allocation of receptive fields in the visual system, according to first principles of measurement and economy. The theory suggests how several previously puzzling results in perceptual  science can be explained as manifestations of an optimization process that divides a large but limited number of neurons between potential stimuli and tasks.

For further information, please contact Clara Schultheiss, 949-824-7569 or

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