Document Detail

Pattern detection in the presence of maskers that differ in spatial phase and temporal offset: threshold measurements and a model.
MedLine Citation:
PMID:  10748921     Owner:  NLM     Status:  MEDLINE    
Four experiments are described in which brief Gabor patterns are detected in the presence of full-field gratings or Gabor patterns that are superimposed in space, but vary in spatial phase and temporal offset (SOA). E1: Threshold versus masker contrast (TvC) functions were determined for relative phases of 0, 90, 180 and 270 degrees at SOA = 0. For 0 degree relative phase, TvC functions decrease (facilitation) and then increase (masking) as contrast increases. For 90 degrees, there is little or no facilitation and thresholds increase with masker contrast. For 180 degrees, the form of the TvC function varies with observer and conditions. E2: Like E1, except that maskers are Gabor patterns. TvC functions are similar in form to those for full-field maskers, but there is less masking. E3: Forward masking. TvC functions were determined for relative phases of 0, 90, and 180 degrees at SOA = -33 ms. The forms of the TvC functions for 0 and 180 degrees are reversed relative to those at SOA = 0. E4: TvP (threshold versus phase) functions were determined for SOA's of -100, -67, -33, 0 and 33 ms at a constant masker contrast of 0.063. Masking occurs at all relative phases. For simultaneous and backward masking, the threshold is minimum for a relative phase of 0 and maximum at 180 degrees. For forward masking, the form of the function is inverted. A model of pattern masking and facilitation (Foley, J. M. (1994a) Journal of the Optical Society of America A, 11, 1710-1719) is extended to account for masker phase and SOA effects. The model assumes four mechanisms tuned to phases 90 degrees apart, and divisively inhibited by stimuli of all phases. Performance depends on the detection strategy of the observer.
J M Foley; C C Chen
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Vision research     Volume:  39     ISSN:  0042-6989     ISO Abbreviation:  Vision Res.     Publication Date:  1999 Nov 
Date Detail:
Created Date:  2000-04-12     Completed Date:  2000-04-12     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0417402     Medline TA:  Vision Res     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  3855-72     Citation Subset:  IM    
Department of Psychology, University of California, Santa Barbara 93106-9660, USA.
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MeSH Terms
Contrast Sensitivity
Fixation, Ocular / physiology
Pattern Recognition, Visual / physiology*
Perceptual Masking
Sensory Thresholds / physiology
Grant Support

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