Document Detail


Are direction and speed coded independently by the visual system? Evidence from visual search.
MedLine Citation:
PMID:  1633133     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Three visual search experiments examined whether motion is coded as two separate features, speed and direction. Increasing the heterogeneity of the directions in which stimuli moved disrupted detection of a target defined by speed (fast among medium and slow nontargets), suggesting that speed is coded integrally with direction. However, heterogeneity in speed did not disrupt detection of a target moving in a particular direction among nontargets with different directions. This suggests that direction is coded independently of speed. The apparent paradox raised by these contrasting conclusions is consistent with neurophysiological and computational models of motion-detection, which suggest that low-levels of the visual system contain direction-detectors insensitive to speed, while speed is coded at higher levels by detectors which are also sensitive to direction. Evidence consistent with the existence of the latter conjunction detectors was obtained in a final experiment which found search for a conjunction of speed and direction to be parallel.
Authors:
J Driver; P McLeod; Z Dienes
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Spatial vision     Volume:  6     ISSN:  0169-1015     ISO Abbreviation:  Spat Vis     Publication Date:  1992  
Date Detail:
Created Date:  1992-08-24     Completed Date:  1992-08-24     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  8602662     Medline TA:  Spat Vis     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  133-47     Citation Subset:  IM; S    
Affiliation:
Department of Experimental Psychology, University of Cambridge, UK.
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MeSH Terms
Descriptor/Qualifier:
Adult
Form Perception / physiology
Humans
Middle Aged
Motion Perception / physiology*
Vision, Ocular / physiology*

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


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