Shape discrimination and the judgement of perfect symmetry: Dissociation of shape from size

Regan, D.; Hamstra, Stanley J.

doi:10.1016/0042-6989(92)90046-l

Cited by 131 publications

(165 citation statements)

References 25 publications

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“…Complex stimuli like faces, after all, are composed of many different local elements, which include, line orientation, curvature, and shape, all properties for which aftereffects have been described (Adams & Mamassian, 2002;Gibson & Rander, 1937;Regan & Hamstra, 1992;Suzuki, 2003;Suzuki & Cavanagh, 1998). If local adaptation to these image elements accounts for a significant portion of face aftereffects, this would significantly constrain the inferences about face space that can be derived from face adaptation studies.…”

Section: Introductionmentioning

confidence: 92%

Factors contributing to the adaptation aftereffects of facial expression

et al. 2008

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Previous studies have demonstrated the existence of adaptation aftereffects for facial expressions. Here we investigated which aspects of facial stimuli contribute to these aftereffects. In Experiment 1 we examined the role of local adaptation to image elements such as curvature, shape and orientation, independent of expression, by using hybrid faces constructed from either the same or opposing expressions. While hybrid faces made with consistent expressions generated aftereffects as large as that with normal faces, there were no aftereffects from hybrid faces made from different expressions, despite the fact that these contained the same local image elements. In Experiment 2 we examined the role of facial features independent of the normal face configuration, by contrasting adaptation with whole faces to adaptation with scrambled faces. We found that scrambled faces also generated significant aftereffects, indicating that expressive features without a normal facial configuration could generate expression aftereffects. In Experiment 3 we examined the role of facial configuration by using schematic faces made from line elements that in isolation do not carry expression-related information (e.g. curved segments and straight lines), but that convey an expression when arranged in a normal facial configuration. We obtained a significant aftereffect for facial configurations but not scrambled configurations of these line elements. We conclude that face expression aftereffects are not due to local adaptation to image elements but due to high-level adaptation of neural representations that involve both facial features and facial configuration.

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Section: Introductionmentioning

confidence: 92%

Factors contributing to the adaptation aftereffects of facial expression

et al. 2008

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“…Kohler and Wallach (1944) reported that a prolonged adaptation to an ellipse makes a subsequently viewed circle presented at the same location appear distorted into an ellipse perpendicular to the adapting ellipse (also see Regan & Hamstra, 1992, for a comprehensive study of aspect-ratio-based aftereffects). Hartmann (1923Hartmann ( /1955, using briefly presented stimuli, observed a similar phenomenon that is more related to the present study.…”

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confidence: 99%

“…The first pair of stimuli whose shape interaction we chose to test consisted of a line (as the priming stimulus) and a circle (as the test stimulus); we chose these stimuli partly because of the historical use of them and partly because people are sensitive in detecting slight distortion effects on a circle (e.g., Regan & Hamstra, 1992). Kohler and Wallach (1944) reported that a prolonged adaptation to an ellipse makes a subsequently viewed circle presented at the same location appear distorted into an ellipse perpendicular to the adapting ellipse (also see Regan & Hamstra, 1992, for a comprehensive study of aspect-ratio-based aftereffects).…”

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confidence: 99%

A shape-contrast effect for briefly presented stimuli.

Suzuki

Cavanagh²

1998

Journal of Experimental Psychology: Human Perception and Perfor

137

155

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“…Because rigidity assumptions are not useful in discerning the shapes of flexing cylinders and the similarity between the slopes of the psychometric curves make it unlikely that entirely separate neural processes are used for flexing than for rigid cylinders, these results suggest that percepts of rigidity may arise as a result of a more general prior assumption. Although observers were able to perform this task in a consistent manner (percent perceived deeper varied monotonically with the aspect ratio, and mean PSCs were within 20% of veridical), the sensitivity observed here is substantially lower than that for discriminating elliptical departures from circular shapes in 2D (53). Computational analyses.…”

Section: Resultsmentioning

confidence: 99%

Discerning nonrigid 3D shapes from motion cues

Jain

Zaidi²

2011

Proc. Natl. Acad. Sci. U.S.A.

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Many organisms and objects deform nonrigidly when moving, requiring perceivers to separate shape changes from object motions. Surprisingly, the abilities of observers to correctly infer nonrigid volumetric shapes from motion cues have not been measured, and structure from motion models predominantly use variants of rigidity assumptions. We show that observers are equally sensitive at discriminating cross-sections of flexing and rigid cylinders based on motion cues, when the cylinders are rotated simultaneously around the vertical and depth axes. A computational model based on motion perspective (i.e., assuming perceived depth is inversely proportional to local velocity) predicted the psychometric curves better than shape from motion factorization models using shape or trajectory basis functions. Asymmetric percepts of symmetric cylinders, arising because of asymmetric velocity profiles, provided additional evidence for the dominant role of relative velocity in shape perception. Finally, we show that inexperienced observers are generally incapable of using motion cues to detect inflation/deflation of rigid and flexing cylinders, but this handicap can be overcome with practice for both nonrigid and rigid shapes. The empirical and computational results of this study argue against the use of rigidity assumptions in extracting 3D shape from motion and for the primacy of motion deformations computed from motion shears.optic-flow | structure-from-motion

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Shape discrimination and the judgement of perfect symmetry: Dissociation of shape from size

Cited by 131 publications

References 25 publications

Factors contributing to the adaptation aftereffects of facial expression

Factors contributing to the adaptation aftereffects of facial expression

A shape-contrast effect for briefly presented stimuli.

Discerning nonrigid 3D shapes from motion cues

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