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Proceedings Paper

Response variability of the red-green color vision system using reaction times
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Paper Abstract

We have studied the intrinsic variability of color coding by examining the temporal fluctuations of chromatic-opponent neurons at the large scale. Simple reaction times were measured for stimuli selected along the red-green direction in the isoluminant plane of the human color space (S-cone constant or L-M axis). Stimulus size also changed from 8 minutes of arc to 10 degrees. Fluctuations increased as the mean reaction time increased and showed a bi-linear scaling function. The coefficient of variation was always lower than predicted by a Poisson process. The variability decreased as a function of the chromatic contrast and as a function of the stimulus size. The analysis of the hazard functions was consistent with power-law dominant random processes at low stimulus size and low contrasts and log-normal dominant processes at high contrasts. Our results conclude that response variability is signal-dependent and evidence for a random multiplicative process in human color vision. We suggest that multiplicative internal noise modulates red-green spatial summation and chromatic contrast processing and may represent a fundamental limit in spatially disordered networks.

Paper Details

Date Published: 26 July 2011
PDF: 9 pages
Proc. SPIE 8001, International Conference on Applications of Optics and Photonics, 80013B (26 July 2011); doi: 10.1117/12.892098
Show Author Affiliations
José M. Medina, Univ. of Minho (Portugal)
José A. Díaz, Univ. of Granada (Spain)

Published in SPIE Proceedings Vol. 8001:
International Conference on Applications of Optics and Photonics
Manuel Filipe Costa, Editor(s)

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