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Lars Strother, Alexandra M. Coros, Tutis Vilis; Edge co-alignment facilitates short-term perceptual memory of global form. Journal of Vision 2012;12(9):883. doi: https://doi.org/10.1167/12.9.883.
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© ARVO (1962-2015); The Authors (2016-present)
Perceptual grouping mechanisms bind spatially local edge information into global contours during form perception and scene segmentation. Relative orientations of adjacent elements comprising a contour play an important role in these perceptual organization processes. For instance, the detectability of a contour embedded in a highly camouflaging background is facilitated by increasing co-alignment of adjacent elements comprising the contour. The present study concerns contour-defined forms that only become visible when cued (by onset, motion, color, etc.), and briefly remain visible after the cue has ended, but eventually disappear (become camouflaged). This type of form-based perceptual persistence exemplifies short-term memory of perceptual organization following the removal of initial binding cues.
We studied the effect of inter-element alignment on the duration of form-based perceptual persistence using circular contours comprised of short line segments that were embedded in a background of randomly oriented line segments. The contours were visible when they first appeared (onset acted as a cue) but always disappeared (became camouflaged) within a few seconds. We varied element co-alignment (co-circular versus random), inter-element distance (of contour and background elements) and the size of the circles these elements formed. Observers indicated when a circle was no longer visible.
We found that circles comprised of co-circular elements persisted longer (took longer to disappear) than equally sized circles comprised of randomly oriented elements equated for position. We also observed an effect of contour and background density such that relatively dense circles persisted longest. Our results are consistent with perceptual grouping models that predict increasing contour visibility (detectability) as a function of increasing inter-element alignment and decreasing distance, even though the contours we used were not visible unless cued. We conclude that contour grouping and the perceptual persistence of global form reflect the operation of common neural mechanisms, and that form-based memory promotes sustained perceptual grouping.
Meeting abstract presented at VSS 2012
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