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Tandra Ghose, Mary A. Peterson; Using Extremal Edge to Decouple Closeness and Shape in Figure-Ground Perception. Journal of Vision 2014;14(10):253. doi: 10.1167/14.10.253.
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Traditionally, the figure is defined as that side of a border that appears both shaped and closer to the viewer than the abutting side. Both Extremal-Edge (EE) and upright familiar configuration are figural cues. Ghose and Palmer (2010) showed observers displays divided into two equal–area regions by an articulated central border and instructed them to report which side appeared closer. Observers chose the EE side on 100% of trials when EE and familiar configuration were present on the same side of the border (Congruent displays) and on 96% of trials when EE and familiar configuration were present on opposite sides (Incongruent displays; the difference of 4% was not statistically significant, p=0.20).Thus, observers overwhelmingly reported that the EE side was closer than the abutting side. We investigated whether the EE side is chosen as often when the task is to report which side of a border appears to be shaped. EE reports were significantly reduced when observers were instructed to report which was the shaped side of a border rather than which was the closer side. Observers reported that the EE side was the shaped side on 94% and 81% of trials with upright Congruent and Incongruent displays, respectively (p=0.029). In addition, the difference between EE-side reports on Congruent and Incongruent trials was larger for the shape task than for the relative distance task, at least when an upright familiar configuration was present on the opposite side of the border of incongruent displays rather than an inverted or a part-rearranged version of a familiar configuration, p <.05. Thus, the figural attributes of shape and near surface can be decoupled. Moreover, different figural cues differentially affect perceived shape and perceived near surface. EE exerts a relatively stronger influence than familiar configuration on the perceived-nearness than the perceived-shape.
Meeting abstract presented at VSS 2014
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