Document Detail

Absence of linear subthreshold summation between red-green and luminance mechanisms over a wide range of spatio-temporal conditions.
MedLine Citation:
PMID:  9196733     Owner:  NLM     Status:  MEDLINE    
We have tested the independence of red-green chromatic and luminance mechanisms at detection threshold using a method of subthreshold summation. Stimuli were isoluminant red-green gratings and yellow-black luminance gratings that uniquely activate the red-green color and luminance mechanisms, respectively. Stimuli were Gaussian enveloped 0.25, 1 or 4 cpd sinewave gratings, counter-phase flickered at 0, 5 or 9 Hz. The threshold detection of red-green color contrast was measured in the presence of a subthreshold amount of luminance contrast, and vice versa. The results allow a model of linear summation between the color and luminance mechanisms to be rejected, but are well fitted by a model, assuming that these mechanisms are independent but combine to determine detection by probability summation, with a high summation index (median value = 4). We conclude that there are independent red-green chromatic mechanism and luminance detection mechanisms over this range of spatio-temporal conditions.
K T Mullen; S J Cropper; M A Losada
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Vision research     Volume:  37     ISSN:  0042-6989     ISO Abbreviation:  Vision Res.     Publication Date:  1997 May 
Date Detail:
Created Date:  1997-07-09     Completed Date:  1997-07-09     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0417402     Medline TA:  Vision Res     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  1157-65     Citation Subset:  IM    
McGill Vision Research, Department of Ophthalmology, McGill University, Montreal, Canada.
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MeSH Terms
Color Perception / physiology*
Contrast Sensitivity / physiology
Models, Neurological
Pattern Recognition, Visual / physiology
Sensory Thresholds / physiology

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