| Contextual effects in speed perception may occur at an early stage of processing. | |
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MedLine Citation:
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PMID: 19925820 Owner: NLM Status: In-Process |
Abstract/OtherAbstract:
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How does nearby motion affect the perceived speed of a target region? When a central drifting Gabor patch is surrounded by translating noise, its speed can be misperceived over a fourfold range. Typically, when a surround moves in the same direction, perceived centre speed is reduced; for opposite-direction surrounds it increases. Measuring this illusion for a variety of surround properties reveals that the motion context effects are a saturating function of surround speed (Experiment I) and contrast (Experiment II). Our analyses indicate that the effects are consistent with a subtractive process, rather than with speed being averaged over area. In Experiment III we exploit known properties of the motion system to ask where these surround effects impact. Using 2D plaid stimuli, we find that surround-induced shifts in perceived speed of one plaid component produce substantial shifts in perceived plaid direction. This indicates that surrounds exert their influence early in processing, before pattern motion direction is computed. These findings relate to ongoing investigations of surround suppression for direction discrimination, and are consistent with single-cell findings of direction-tuned suppressive and facilitatory interactions in primary visual cortex (V1). |
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Authors:
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Daniel H Baker; Erich W Graf |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2009-11-16 |
Journal Detail:
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Title: Vision research Volume: 50 ISSN: 1878-5646 ISO Abbreviation: Vision Res. Publication Date: 2010 Jan |
Date Detail:
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Created Date: 2010-01-29 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0417402 Medline TA: Vision Res Country: England |
Other Details:
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Languages: eng Pagination: 193-201 Citation Subset: IM |
Affiliation:
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School of Psychology, University of Southampton, Highfield, Southampton, SO17 1BJ, UK. d.h.baker1@aston.ac.uk |
Export Citation:
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Descriptor/Qualifier:
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| Grant Support | |
ID/Acronym/Agency:
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BB/E012698/1//Biotechnology and Biological Sciences Research Council |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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