Document Detail

Detection of flickering edges: absence of a red-green edge detector.
MedLine Citation:
PMID:  10755156     Owner:  NLM     Status:  MEDLINE    
Kelly ((1975) Science, 188, 371-372) showed that a centrally-fixated, contrast-reversing edge has a very different effect on the detection of luminance and red-green flicker. Red-green flicker sensitivity was approximately 3-fold greater for a uniform field than for a 'split' field with the two sides flickering out-of-phase. Just the opposite effects were observed for luminance flicker--the split field yielded a 7-fold advantage over the uniform field at 2 or 4 Hz and a 3-fold advantage at 12 Hz. Contrary to Kelly, we find that the split field offers only a very small advantage of 40% for luminance flicker at 2 Hz and virtually no advantage at 4 Hz and above. Kelly's chromatic results are surprising since one might expect that the larger color difference (or step) across the central edge would aid chromatic discrimination rather than strongly suppressing sensitivity. We show that the central chromatic edge only weakly impairs detection. Further results show that the two sides of the chromatic split field are detected essentially independently by red or green 'blob' detectors, which do not take advantage of the color difference across the edge. This has a remarkable implication: when wavelength discrimination is measured with a bipartite field whose two side are slowly modulated in opposite directions, then one side may be deleted with little adverse effect.
P D Gowdy; C F Stromeyer; R E Kronauer
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Publication Detail:
Type:  Journal Article; 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  
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:  4186-91     Citation Subset:  IM    
Department of Psychology, Harvard University, Cambridge, MA 02138, USA.
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MeSH Terms
Color Perception / physiology*
Contrast Sensitivity / physiology
Flicker Fusion / physiology*
Photic Stimulation / methods
Grant Support

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