Document Detail

Stimulus magnification equates identification and discrimination of biological motion across the visual field.
MedLine Citation:
PMID:  18848575     Owner:  NLM     Status:  MEDLINE    
There is conflicting evidence about whether stimulus magnification is sufficient to equate the discriminability of point-light walkers across the visual field. We measured the accuracy with which observers could report the directions of point-light walkers moving +/-4 degrees from the line of sight, and the accuracy with which they could identify five different point-light walkers. In both cases accuracy was measured over a sevenfold range of sizes at eccentricities from 0 degrees to 16 degrees in the right visual field. In most cases observers (N=6) achieved 100% accuracy at the largest stimulus sizes (20 degrees height) at all eccentricities. In both tasks the psychometric functions at each eccentricity were shifted versions of each other on a log-size axis. Therefore, by dividing stimulus size at each eccentricity (E) by an appropriate F=1+E/E(2) (where E(2) represents the eccentricity at which stimulus size must double to achieve equivalent-to-foveal performance) all data could be fit with a single function. The average E(2) value was .91 (SEM=.19, N=6) in the walker-direction discrimination task and 1.34 (SEM=.21, N=6) in the walker identification task. We conclude that size scaling is sufficient to equate discrimination and identification of point-light walkers across the visual field.
Rick Gurnsey; Gabrielle Roddy; Marouane Ouhnana; Nikolaus F Troje
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Publication Detail:
Type:  Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't     Date:  2008-11-01
Journal Detail:
Title:  Vision research     Volume:  48     ISSN:  1878-5646     ISO Abbreviation:  Vision Res.     Publication Date:  2008 Dec 
Date Detail:
Created Date:  2008-11-17     Completed Date:  2009-10-09     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0417402     Medline TA:  Vision Res     Country:  England    
Other Details:
Languages:  eng     Pagination:  2827-34     Citation Subset:  IM    
Department of Psychology, Concordia University, 7141 Sherbrooke Street West, Montreal, Que., Canada H4B 1R6.
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MeSH Terms
Discrimination (Psychology)*
Fixation, Ocular / physiology
Middle Aged
Motion Perception / physiology*
Photic Stimulation / methods
Sensory Thresholds / physiology
Visual Fields / physiology*
Young Adult

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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