Document Detail

Vernier acuity with plaid masks: the role of oriented filters in vernier acuity.
MedLine Citation:
PMID:  9205724     Owner:  NLM     Status:  MEDLINE    
Superimposition of oriented grating masks on vernier targets results in bimodal patterns of vernier threshold elevation, with peaks occurring on either side of vernier target orientation. These bimodal masking effects suggest a contribution to vernier acuity from spatial filters tuned to orientations on either side of the target. We report similar bimodal threshold elevation with plaid masks composed of symmetrically oriented pairs of gratings. Since filters oriented to either side of the vernier stimulus will be affected similarly by plaid masks, it is unlikely that threshold elevation reflects disruption of relative filter activity that is used to code for change in target orientation. Instead, the results support the proposition that misalignments are detected on the basis of differential (i.e. absolute rather than relative) activity of spatial filters. Our plaid-mask data also rule out the possibility that: (i) "off-channel" looking; or (ii) detection of orientation shifts (e.g. tilt illusions), underlie bimodal masking effects. The finding that weak bimodal threshold elevation occurs with dot targets separated by 40 min arc further suggests that the mechanisms involved in detecting misalignments over large regions [possibly collator/collector-type mechanisms] also do so via analysis of their differential activity.
A J Mussap; D M Levi
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Vision research     Volume:  37     ISSN:  0042-6989     ISO Abbreviation:  Vision Res.     Publication Date:  1997 May 
Date Detail:
Created Date:  1997-07-14     Completed Date:  1997-07-14     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0417402     Medline TA:  Vision Res     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  1325-40     Citation Subset:  IM    
College of Optometry, University of Houston, TX 77204-6052, USA.
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MeSH Terms
Contrast Sensitivity
Form Perception / physiology*
Models, Neurological
Pattern Recognition, Visual / physiology*
Perceptual Masking
Sensory Thresholds / physiology
Grant Support

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

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