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Robert F Hess, Tim Ledgeway; The spatial properties of motion-defined contours?. Journal of Vision 2003;3(9):787. doi: 10.1167/3.9.787.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose. The visual system integrates local orientation information across space to define spatial contours (Field, et al V.R. 33, 1993). More recently, it has been shown that a similar integration occurs for the direction of local motion signals in different parts of the field if they are aligned along a spatial contour (Ledgeway & Hess ARVO, 2001). Here we ask what are the spatial properties of this specialized type of motion integration. Methods Using a standard 2AFC task, observers were asked to choose which interval contained the elongated spatial contour (path) defined solely by motion. One interval chosen at random on each trial contained 158 micropatterns of random position and direction (background micropatterns) and in the other interval (path plus background) the motion directions of some (8) of the background micropatterns were arranged to lie along the invisible backbone of an elongated contour. The micropatterns contained 2-d, spatial noise that either had a spatial frequency bandwidth of 1 octave (Expt 1) or had an orientation bandwidth of 30 (Expt 2) and the centre frequencies/orientations of individual micropatterns could be varied. Results Motion-defined contours exhibit broad tuning for spatial frequency but narrow tuning for orientation. Conclusions Although motion-defined contours differ from orientation-defined counterparts in terms of their spatial frequency tuning they both exhibit narrow orientation tuning.
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