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Stephen E. Palmer, Joseph L. Brooks; Grouping occurs both before and after constancy. Journal of Vision 2002;2(7):702. doi: https://doi.org/10.1167/2.7.702.
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© ARVO (1962-2015); The Authors (2016-present)
Previous results from our laboratory have shown that perceptual grouping occurs after various kinds of constancy processing, because perceived grouping can be strongly influenced by depth, post-constancy lightness perception, amodal completion, and illusory contours. We now report results showing that grouping also occurs before constancy processing. The general logic is to demonstrate that grouping both affects constancy and is affected by constancy. In shape constancy, for example, we first demonstrate that pictorial depth cues influence whether observers see a central column of ambiguous ovals as grouping with circles in the frontal plane or with ovals in the frontal plane. We then also show that whether observers perceive an ambiguous oval as a circle slanted in depth or as an oval in the frontal plane is strongly influenced by whether it is grouped with a surrounding trapezoid (consistent with the circular interpretation) or with a surrounding square (consistent with the oval interpretation). Proximity, common fate, and color similarity all have strong effects in our displays. We have also demonstrated similar kinds of grouping effects on edge assignment in depth perception for textured surfaces: the edge is assigned to the region whose texture elements group with the edge according to factors such as common fate, proximity, color similarity, and orientational similarity. Analogous grouping effects also appear to occur in displays involving lightness constancy. These results are inconsistent with aspects of Palmer and Rock's (1994) theory of perceptual organization, but consistent with an alternative formulation in which grouping occurs throughout perceptual processing.
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