| Simultaneous encoding of direction at a local and global scale. | |
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MedLine Citation:
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PMID: 9529903 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Human observers can simultaneously encode direction information at two different scales, one local (an individual dot) and one global (the coherent motion of a field of dots distributed over a 10 degrees-diameter display). We assessed whether encoding global motion would preclude the encoding of a local trajectory component and vice versa. In the present experiments, a large number (100-150) of dots were randomly assigned directions in each frame from a uniform distribution of directions spanning a range of 160 degrees to create global motion in a single direction (Williams & Sekuler, 1984). Amidst these background dots, 1 dot moved in a consistent direction (trajectory) for the duration of the display. The direction of this "trajectory dot" was similar to the mean direction of the distribution of directions determining the movement of the background dots. Direction discrimination for both the global motion and the trajectory was measured, using the method of constant stimuli, under precued and postcued partial report conditions. A low- or high-frequency 85-msec tone signaled which motion the subject was to judge. In the precue condition, the tone was presented 200 msec before the onset of the stimulus, whereas in the postcue condition, the tone was presented immediately after the offset of the stimulus. Direction discrimination thresholds for both global and local motion in the postcued condition were not significantly different from those obtained in the precued condition. These results suggest that direction information for both global and local motion is encoded simultaneously and that the observer has access to either motion signal after the presentation of a stimulus. |
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Authors:
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S N Watamaniuk; S P McKee |
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Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, Non-P.H.S. |
Journal Detail:
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Title: Perception & psychophysics Volume: 60 ISSN: 0031-5117 ISO Abbreviation: Percept Psychophys Publication Date: 1998 Feb |
Date Detail:
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Created Date: 1998-04-28 Completed Date: 1998-04-28 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0200445 Medline TA: Percept Psychophys Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 191-200 Citation Subset: IM |
Affiliation:
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Psychology Department, Wright State University, Dayton, OH 45435, USA. swatamaniuk@wright.edu |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Attention* Cues Female Humans Male Middle Aged Motion Perception* Orientation* Pattern Recognition, Visual* Psychophysics Sensory Thresholds |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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