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Alexander Rose-Henig, Arthur G. Shapiro, Zhong-Lin Lu; Motion path misidentification in the periphery. Journal of Vision 2012;12(9):1225. doi: 10.1167/12.9.1225.
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Examination of motion illusions in foveal and peripheral vision have led to the ‘‘feature blur’’ hypothesis: the peripheral visual system combines features that the foveal visual system can separate (Shapiro, Knight, Lu, 2011, journal.pone.0018719). Others have hypothesized that processes that underlie crowding limit multiple object tracking. Here, we investigate the perception of motion paths of two objects that follow opposite rotational directions; we hypothesized that objects that follow the same path may produce misidentifications that depend on eccentricity. The stimulus consists of two 1-deg disks, one filed with a radial sine-wave pattern (concentric rings), the other with a tangential sine-wave pattern (spokes on a wheel); one disk rotates clockwise around a central point while the other rotates counter-clockwise. When viewed in the periphery (in some conditions), the disks do not seem to follow circular paths but rather appear as an elliptical jumble of the two disks; however, when one disk is made invisible, the remaining disk appears to travel in a circular path. We measured the critical size of the circular path (i.e., the size at which there is a transition between the percept of a circular path and jumbled ellipses) at five different eccentricities; the results showed that the critical size is equal to 0.291*eccentricity-2.67, which is similar to Bauma’s law of crowding (slope between 0.1 and 0.5). In addition we have produced demonstrations that clearly show that the critical size of the circular path decreases when the relative contrast, color and spatial frequency of the two disks are dissimilar to each other (i.e., two disks seem appear to follow jumbled ellipses when they are similar, but follow circular paths when their features are different from each other). Conclusion: motion path misidentification in the visual periphery depends on eccentricity, similar in principle to Bauma’s law in visual crowding.
Meeting abstract presented at VSS 2012
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