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Robert Hess, Craig Aaen-Stockdale; Global Motion: effects of spatial scale and eccentricity. Journal of Vision 2007;7(9):394. doi: 10.1167/7.9.394.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose. Much is known about global motion processing, the ability to extract the global motion attributes from a collection of noisy local motion signals. Less is known about its dependence on spatial scale and eccentricity because it has been general practice to use large fields of spatially broadband stimuli. Here we first look at the effects of spatial scale and, equipped with this knowledge, explore the dependence on eccentricity. Methods Our stimulus comprised an array of spatially bandpass elements in which some of the elements (signal) move in a coherent direction while the other elements (noise) move in a random direction. We vary the contrast of the individual elements and measure, using a standard 2AFC task, the signal/noise threshold (coherence) for motion direction.Results The detectability of the elements is strongly spatial scale dependent as is the influence of eccentricity, however coherence thresholds are, to a large extent, independent of both spatial scale and eccentricity. Conclusion The effects of spatial scale and eccentricity being strongly contrast dependent reflect the low-level dependencies of local motion processing. At the level where global integration occurs such factors exert only small effects.
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