| Occlusion and the solution to visual motion ambiguity: Looking beyond the aperture problem. | |
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MedLine Citation:
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PMID: 18318630 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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A horizontally moving grating viewed within a diamond-shaped aperture can be made to appear to move obliquely by introducing appropriate depth-ordering cues (R. O. Duncan, T. D. Albright, & G. R. Stoner, 2000). It is commonly assumed that the depth cues in such displays determine which line terminators are seen as intrinsic to the grating and which are seen as resulting from occlusion and hence extrinsic to the grating. The ambiguous motion of the grating (arising from the aperture problem) is then supposed to be overcome by selectively pooling motion signals arising from the intrinsic terminators with those arising from the grating while discounting the motion of the extrinsic terminators. In our first experiment, we tested the sufficiency of this explanation. Observers reported the direction of motion of ambiguously moving random dots viewed through a diamond-shaped aperture defined by four panels. Binocular disparity was used to simulate occlusion: two panels occluded the virtual surface upon which the dots were positioned and two panels were occluded by that surface. Reports were significantly biased toward the direction of the occluding panels. Since none of the moving features abutted the surrounding panels, none should have been classified as extrinsic and hence this result cannot have relied on terminator classification. In a second experiment, we tested the hypothesis that depth-ordering cues selectively gate the propagation of motion signals so that the representation of the moving surface extends behind the occluders. This was tested by asking observers to report the direction of moving dots viewed through a briefly "opened" probe window within either occluding or occluded panels. Consistent with our hypothesis, evidence of motion propagation was only found for probe windows within occluding panels. Surprisingly, however, this propagation was only observed when the dots in the inducer window moved away from the probe window, suggesting a "pull," and not a "push" mechanism. |
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Authors:
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Maarten J van der Smagt; Gene R Stoner |
Publication Detail:
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Type: Comparative Study; Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't Date: 2008-02-20 |
Journal Detail:
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Title: Journal of vision Volume: 8 ISSN: 1534-7362 ISO Abbreviation: J Vis Publication Date: 2008 |
Date Detail:
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Created Date: 2008-03-05 Completed Date: 2008-03-20 Revised Date: 2008-04-29 |
Medline Journal Info:
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Nlm Unique ID: 101147197 Medline TA: J Vis Country: United States |
Other Details:
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Languages: eng Pagination: 4.1-12 Citation Subset: IM |
Affiliation:
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Experimental Psychology, Helmholtz Institute and Utrecht University, Utrecht, The Netherlands. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Depth Perception
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physiology* Humans Motion Perception / physiology* Optical Illusions / physiology* Pattern Recognition, Visual / physiology Photic Stimulation Vision Disparity / physiology* Vision, Binocular / physiology |
| Grant Support | |
ID/Acronym/Agency:
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2R01EY12872-05/EY/NEI NIH HHS; //Howard Hughes Medical Institute |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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