Document Detail

Segregation by onset asynchrony.
MedLine Citation:
PMID:  19146254     Owner:  NLM     Status:  MEDLINE    
We describe a simple psychophysical paradigm for studying figure-ground segregation by onset asynchrony. Two pseudorandom arrays of Gabor patches are displayed, to left and right of fixation. Within one array, a subset of elements form a figure, such as a randomly curving path, that can only be reliably detected when their onset is not synchronized with that of the background elements. Several findings are reported. First, for most participants, segregation required an onset asynchrony of 20-40 ms. Second, detection was no better when the figure was presented first, and thus by itself, than when the background elements were presented first, even though in the latter case the figure could not be detected in either of the two successive displays alone. Third, asynchrony segregated subsets of randomly oriented elements equally well. Fourth, asynchronous onsets aligned with the path could be discriminated from those lying on the path but not aligned with it. Fifth, both transient and sustained neural activity contribute to detection. We argue that these findings are compatible with neural signaling by synchronized rate codes. Finally, schizophrenic disorganization is associated with reduced sensitivity. Thus, in addition to bearing upon basic theoretical issues, this paradigm may have clinical utility.
P J B Hancock; L Walton; G Mitchell; Y Plenderleith; W A Phillips
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Publication Detail:
Type:  Comparative Study; Journal Article     Date:  2008-08-05
Journal Detail:
Title:  Journal of vision     Volume:  8     ISSN:  1534-7362     ISO Abbreviation:  J Vis     Publication Date:  2008  
Date Detail:
Created Date:  2009-01-16     Completed Date:  2009-05-05     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101147197     Medline TA:  J Vis     Country:  United States    
Other Details:
Languages:  eng     Pagination:  21.1-21     Citation Subset:  IM    
Department Psychology, University of Stirling, UK.
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MeSH Terms
Attention / physiology*
Chronic Disease
Middle Aged
Models, Theoretical
Pattern Recognition, Visual / physiology*
Photic Stimulation
Schizophrenia / physiopathology*
Task Performance and Analysis
Young Adult

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