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Published on: January 23, 2017
The invariance of directional tuning with contrast and coherence
I Fine1, C M Anderson, G M Boynton
1Department of Psychology, UC San Diego, La Jolla, CA, USA. ifine@dohenyeyeinstitute.org
Abstract:
The responses of motion mechanisms depend not only on the direction of a stimulus, but also on its contrast, coherence and speed. We examined how contrast, coherence and directional selectivity interact by measuring directional tuning psychophysically across a wide range of coherence and contrast levels. We fit data with a simple model that estimated directional tuning bandwidth using contrast and coherence gain parameters that were based on neurophysiological estimates. This model estimated a bandwidth of approximately 90 degrees for directionally selective mechanisms. Bandwidth was invariant across a wide range of contrasts and coherences, as predicted by models of contrast normalization.
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