Document Detail


The human visual system averages speed information.
MedLine Citation:
PMID:  1604862     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
It has been known for many years that human observers are unable to detect modest accelerations and decelerations in moving visual stimuli. We find that human observers can integrate speeds over many dots, moving at different speeds, producing a global speed percept analogous to the global direction percept first reported by Williams, D. W. and Sekuler, R. (1984, Vision Research, 24, 55-62). We measured speed discrimination for random dot stimuli which contained many different speeds. Our results show that observers always base their discrimination on the mean speed of the stimulus; changes in other stimulus characteristics (e.g. mode) are not detected. Moreover, discrimination thresholds for the global mean speed derived from many different speeds are comparable to those obtained with stimuli in which all dots move at the same speed suggesting that the internal noise associated with the encoding of speed information is quite high.
Authors:
S N Watamaniuk; A Duchon
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Vision research     Volume:  32     ISSN:  0042-6989     ISO Abbreviation:  Vision Res.     Publication Date:  1992 May 
Date Detail:
Created Date:  1992-07-16     Completed Date:  1992-07-16     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0417402     Medline TA:  Vision Res     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  931-41     Citation Subset:  IM; S    
Affiliation:
Northwestern University, Department of Psychology, Evanston, IL 60208.
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MeSH Terms
Descriptor/Qualifier:
Differential Threshold / physiology
Discrimination (Psychology) / physiology
Humans
Male
Motion Perception / physiology*
Pattern Recognition, Visual / physiology
Time Factors

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