| Peripheral sensitivity to biological motion conveyed by first and second-order signals. | |
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MedLine Citation:
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PMID: 19895827 Owner: NLM Status: In-Process |
Abstract/OtherAbstract:
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There is evidence that human observers are more sensitive to the direction-of-heading of point-light walkers defined by first-order than second-order motions. We addressed this question by measuring the minimum direction difference (azimuth) that observers could discriminate when the dots composing the walkers were conveyed by first or second-order motions. Sensitivity to azimuth differences for four stimulus types (two first-order and two second-order) was tested at a range of stimulus sizes and at eccentricities of 0-16 degrees in the right visual field. We find that for most stimulus types and eccentricities any azimuth threshold can be obtained by an appropriate adjustment of stimulus size. To achieve a given azimuth threshold second-order stimuli must be larger than the corresponding first-order stimuli. Therefore, stimulus magnification equates sensitivity to walker direction and we may say that sensitivity to walker direction is generally cue-independent. Similarly, in most cases stimulus magnification is sufficient to eliminate eccentricity dependent variability from the azimuth thresholds. Interestingly, the magnification required match peripheral to foveal thresholds increases faster with eccentricity for first-order stimuli than for second-order stimuli, while at the same time thresholds for first-order stimuli are lower than those for second-order stimuli at corresponding sizes and eccentricities. |
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Authors:
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Rick Gurnsey; Nikolaus F Troje |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2009-11-04 |
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: 127-35 Citation Subset: IM |
Affiliation:
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Department of Psychology, Concordia University, 7141 Sherbrooke St. West, Montreal, Quebec, Canada H4B 1R6. Rick.Gurnsey@concordia.ca |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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