| What is second-order vision for? Discriminating illumination versus material changes. | |
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MedLine Citation:
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PMID: 20884600 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The human visual system is sensitive to second-order modulations of the local contrast (CM) or amplitude (AM) of a carrier signal. Second-order cues are detected independently of first-order luminance signals; however, it is not clear why vision should benefit from second-order sensitivity. Analysis of the first- and second-order contents of natural images suggests that these cues tend to occur together, but their phase relationship varies. We have shown that in-phase combinations of LM and AM are perceived as a shaded corrugated surface whereas the anti-phase combination can be seen as corrugated when presented alone or as a flat material change when presented in a plaid containing the in-phase cue. We now extend these findings using new stimulus types and a novel haptic matching task. We also introduce a computational model based on initially separate first- and second-order channels that are combined within orientation and subsequently across orientation to produce a shading signal. Contrast gain control allows the LM + AM cue to suppress responses to the LM - AM when presented in a plaid. Thus, the model sees LM - AM as flat in these circumstances. We conclude that second-order vision plays a key role in disambiguating the origin of luminance changes within an image. |
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Authors:
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Andrew J Schofield; Paul B Rock; Peng Sun; Xiaoyue Jiang; Mark A Georgeson |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2010-07-16 |
Journal Detail:
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Title: Journal of vision Volume: 10 ISSN: 1534-7362 ISO Abbreviation: J Vis Publication Date: 2010 |
Date Detail:
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Created Date: 2010-10-04 Completed Date: 2011-01-24 Revised Date: - |
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: 2 Citation Subset: IM |
Affiliation:
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School of Psychology, University of Birmingham, Birmingham, UK. a.j.schofield@bham.ac.uk |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Contrast Sensitivity
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physiology* Cues Depth Perception / physiology* Discrimination (Psychology) / physiology Humans Lighting* Models, Neurological* Orientation / physiology Photic Stimulation / methods Surface Properties |
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