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Lynn Olzak, Pentti I Laurinen; A framework for understanding center-surround interactions in apparent contrast and fine spatial discriminations. Journal of Vision 2005;5(12):79. doi: https://doi.org/10.1167/5.12.79.
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© ARVO (1962-2015); The Authors (2016-present)
When performing fine spatial discriminations on a center patch of grating surrounded by a similar annulus, results show peculiar but characteristic patterns. Like results of studies using apparent contrast as a measure of center/surround interactions, discrimination performance is slightly facilitated at low surround contrasts and somewhat diminished at high surround contrasts. These effects are widely attributed to lateral inhibition among V1 cells in apparent contrast models. We have previously reported these interactions to be non-symmetric between center and surround, suggesting that mechanisms mediating image segmentation also play a role. When center and surround contrasts are equal, discrimination performance and apparent contrast results diverge. Discrimination plunges to near chance levels (increased effect), whereas apparent contrast is restored to near veridical levels (decreased effect). In both cases, the percept is of a single, large grating. All of these results can be accounted for within a relatively simple two-mechanism, two tier framework that we are developing. The model incorporates lateral gain control mechanisms and circuits that sum values within a stimulus dimension (i.e., spatial frequency)over space, but only within an object.
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