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- Lee, Young-Lim, et al.
(författare)
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Object recognition using metric shape
- 2012
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Ingår i: Vision Research. - : Elsevier BV. - 0042-6989 .- 1878-5646. ; 69, s. 23-31
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Tidskriftsartikel (refereegranskat)abstract
- Most previous studies of 3D shape perception have shown a general inability to visually perceive metric shape. In line with this, studies of object recognition have shown that only qualitative differences, not quantitative or metric ones can be used effectively for object recognition. Recently. Bingham and Lind (2008) found that large perspective changes (>= 45 degrees) allow perception of metric shape and Lee and Bingham (2010) found that this, in turn, allowed accurate feedforward reaches-to-grasp objects varying in metric shape. We now investigated whether this information would allow accurate and effective recognition of objects that vary in respect to metric shape. Both judgment accuracies (d') and reaction times confirmed that, with the availability of visual information in large perspective changes, recognition of objects using quantitative as compared to qualitative properties was equivalent in accuracy and speed of judgments. The ability to recognize objects based on their metric shape is, therefore, a function of the availability or unavailability of requisite visual information. These issues and results are discussed in the context of the Two Visual System hypothesis of Milner and Goodale (1995, 2006).
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| 2. |
- Lee, Young Lim, et al.
(författare)
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Perceived 3D metric (or Euclidean) shape is merely ambiguous, not systematically distorted
- 2013
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Ingår i: Experimental Brain Research. - : Springer Science and Business Media LLC. - 0014-4819 .- 1432-1106. ; 224:4, s. 551-555
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Tidskriftsartikel (refereegranskat)abstract
- Many studies have reported that perceived shape is systematically distorted, but Lind et al. (Inf Vis 2:51-57, 2003) and Todd and Norman (Percept Psychophys 65:31-47, 2003) both found that distortions varied with tasks and observers. We now investigated the hypothesis that perception of 3D metric (or Euclidean) shape is ambiguous rather than systematically distorted by testing whether variations in context would systematically alter apparent distortions. The task was to adjust the aspect ratio of an ellipse on a computer screen to match the cross-section of a target elliptical cylinder object viewed in either frontoparallel elliptical cross-section (2D) or elliptical cross-section in depth (3D). Three different groups were tested using two tasks and two different ranges of aspect ratio: Group 1) 2D(Small) -> 3D(Large), Group 2) 2D(Large) -> 3D(Small), Group 3a) 2D(Small) -> 3D(Small), and Group 3b) 2D(Large) -> 3D(Large). Observers performed the 2D task accurately. This provided the context. The results showed the expected order of slopes when judged aspect ratios were regressed on actual aspect ratios: Group 1 (SL) < Group 3 (SS and LL) < Group 2 (LS). The ambiguity of perceived 3D aspect ratios allowed the range of aspect ratios experienced in the 2D task to affect the 3D judgments systematically. Nevertheless, when the 2D and 3D ranges of aspect ratios were the same (LL and SS) and the 2D were judged accurately, this did not yield accurate 3D judgments. The results supported the hypothesis that perceived 3D metric shape is merely ambiguous rather than systematically distorted.
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| 3. |
- Lind, Mats, et al.
(författare)
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Affine operations plus symmetry yield perception of metric shape with large perspective changes (≥ 45 degrees) : Data and model
- 2014
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Ingår i: Journal of Experimental Psychology. - : American Psychological Association (APA). - 0096-1523 .- 1939-1277. ; 40:1, s. 83-93
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Tidskriftsartikel (refereegranskat)abstract
- G. P. Bingham and M. Lind (2008, Large continuous perspective transformations are necessary and sufficient for accurate perception of metric shape, Perception & Psychophysics, Vol. 70, pp. 524-540) showed that observers could perceive metric shape, given perspective changes >= 45 degrees relative to a principal axis of elliptical cylinders. In this article, we tested (a) arbitrary perspective changes of 45 degrees, (b) whether perception gradually improves with more perspective change, (c) speed of rotation, (d) whether this works with other shapes (asymmetric polyhedrons), (e) different slants, and (f) perspective changes >45 degrees. Experiment 1 compared 45 degrees perspective change away from, versus centered on, a principal axis. Observers adjusted an ellipse to match the cross-section of an elliptical cylinder viewed in a stereo-motion display. Experiment 2 tested whether performance would improve gradually with increases in perspective change, or suddenly with a 45 degrees change. We also tested speed of rotation. Experiment 3 tested (a) asymmetric polyhedrons, (b) perspective change beyond 45 degrees, and (c) the effect of slant. The results showed (a) a particular perspective was not required, (b) judgments only improved with >= 45 degrees change, (c) speed was not relevant, (d) it worked with asymmetric polyhedrons, (e) slant was not relevant, and (f) judgments remained accurate beyond 45 degrees of change. A model shows how affine operations, together with a symmetry yielded by 45 degrees perspective change, bootstrap perception of metric shape.
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