Document Detail

Chromatic and contrast selectivity in color contrast adaptation.
MedLine Citation:
PMID:  15518214     Owner:  NLM     Status:  MEDLINE    
We used color contrast adaptation to examine the chromatic and contrast selectivity of central color mechanisms. Adaptation to a field whose color varies along a single axis of color space induces a selective loss in sensitivity to the adapting axis. The resulting changes in color appearance are consistent with mechanisms formed by different linear combinations of the cone signals. We asked whether the visual system could also adjust to higher-order variations in the adapting stimulus, by adapting observers to interleaved variations along both the L versus M and the S versus LM cardinal axes. The perceived hue of test stimuli was then measured with an asymmetric matching task. Frequency analysis of the hue shifts revealed weak but systematic hue rotations away from each cardinal axis and toward the diagonal intermediate axes. Such shifts could arise if the adapted channels include mechanisms with narrow chromatic selectivity, as some physiological recordings suggest, but could also reflect how adaptation alters the contrast response function. In either case they imply the presence of more than two mechanisms within the chromatic plane. In a second set of measurements, we adapted to either the L versus M or the S versus LM axis alone and tested whether the changes in hue could be accounted for by changes in relative contrast along the two axes. For high contrasts the hue biases are larger than the contrast changes predict. This dissociation implies that the contrast and hue changes are not carried by a common underlying signal, and could arise if the contrast along a single color direction is encoded by more than one mechanism with different contrast sensitivities or if different subsets of channels encode contrast and hue. Such variations in contrast sensitivity are also consistent with physiological recordings of cortical neurons.
Yoko Mizokami; Carrie Paras; Michael A Webster
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Visual neuroscience     Volume:  21     ISSN:  0952-5238     ISO Abbreviation:  Vis. Neurosci.     Publication Date:    2004 May-Jun
Date Detail:
Created Date:  2004-11-02     Completed Date:  2005-01-11     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  8809466     Medline TA:  Vis Neurosci     Country:  England    
Other Details:
Languages:  eng     Pagination:  359-63     Citation Subset:  IM    
Department of Psychology, University of Nevada, Reno 89557, USA.
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MeSH Terms
Adaptation, Ocular / physiology*
Color Perception / physiology*
Contrast Sensitivity / physiology*
Pattern Recognition, Visual
Photic Stimulation / methods
Visual Fields / physiology
Grant Support

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

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