| Visual discrimination of direction changes based upon two types of angular motion. | |
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MedLine Citation:
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PMID: 10343781 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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We address the question of how the visual system analyses changes in direction. Using plaid stimuli, we define type O direction changes which entail a change in the orientations of the plaid components, and type V direction changes in which the orientations of the components remain constant, relative to the observer but their relative speeds change. Lower thresholds for discriminating type O and type V direction changes were compared. Type O thresholds for clockwise/anticlockwise direction change were very low (0.2-0.5 degree), were resistant to directional noise, and showed a low-pass relationship with drift velocity. Type V thresholds on the other hand were higher (1-5 degrees), and exhibited a bandpass relationship with drift velocity. Type O direction changes gave low thresholds at short inter-stimulus intervals (ISI) (< 160 ms) and higher thresholds (successive orientation discrimination) at long ISI (240 ms-12.8 s). Type V thresholds, on the other hand, exhibited no short-range process and performance at short ISI, was no better than for successive direction discrimination at long ISI. A two-stage rotary motion model is sufficient to explain the discrimination of type O direction changes and results rule out a model based on velocity discrimination. For type V direction changes, a two-stage mechanism is insufficient and results are consistent with a minimum of three computational stages. |
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Authors:
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M J Wright; K N Gurney |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Vision research Volume: 39 ISSN: 0042-6989 ISO Abbreviation: Vision Res. Publication Date: 1999 Jun |
Date Detail:
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Created Date: 1999-06-14 Completed Date: 1999-06-14 Revised Date: 2006-11-15 |
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: 1927-41 Citation Subset: IM; S |
Affiliation:
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Department of Human Sciences, Brunel University, Uxbridge, UK. michael.wright@brunel.ac.uk |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Humans Male Motion Perception / physiology* Pattern Recognition, Visual / physiology* Rotation Sensory Thresholds / physiology Time Factors |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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