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David F. Nichols, Howard S. Hock; The contributions of edges and surfaces to the perception of object motion. Journal of Vision 2005;5(8):657. doi: https://doi.org/10.1167/5.8.657.
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The motion of objects moving through space potentially can be perceived based on the displacement of their borders or surface parts. When an object shifts multiples of its width, the location of its borders and surface both change, and thus both could give a motion signal. However, when an object with a uniform surface shifts only a small fraction of its width, luminance changes are confined to its leading and trailing edges. Experiments were conducted to determine whether there are two motion signals available for the motion system to use, an edge-based signal and a surface-based signal. The experimental paradigm involved a solid rectangle that remained fixed in place, flanked on each side by an adjacent rectangle. The luminance of the flankers alternated in two-frame display cycles. When the flankers were small, the static central rectangle was perceived to move back and forth. When the flankers were larger, motion was perceived locally within the flankers. With even larger flankers, the perception was of a flanker moving back and forth across the central rectangle. The above results, as well as the results of other experimental manipulations, are consistent with a system of motion perception that extracts edge-based and surface-based motion information, competition arising when they signal different motion paths. Both the edge-based and surface-based motion depends on counterchange in activation, i.e. activation decreases in one location and increases in another, with motion being signaled from the location of the activation decrease to the location of the activation increase (Gilroy & Hock, 2004; Hock & Gilroy, 2004; Nichols & Hock, 2004).
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