Simple visual-reaction times (VRT) were measured for a variety of stimuli selected along red-green (L−M axis) and blue-yellow [S−(L+M) axis] directions in the isoluminant plane under different adaptation stimuli. Data were plotted in terms of the RMS cone contrast in contrast-threshold units. For each opponent system, a modified Piéron function was fitted in each experimental configuration and on all adaptation stimuli. A single function did not account for all the data, confirming the existence of separate postreceptoral adaptation mechanisms in each opponent system under suprathreshold conditions. The analysis of the VRT-hazard functions suggested that both color-opponent mechanisms present a well-defined, transient-sustained structure at marked suprathreshold conditions. The influence of signal polarity and chromatic adaptation on each color axis proves the existence of asymmetries in the integrated hazard functions, suggesting separate detection mechanisms for each pole (red, green, blue, and yellow detectors).
© 2006 Optical Society of America
Vision and color
Original Manuscript: May 11, 2005
Revised Manuscript: November 14, 2005
Manuscript Accepted: November 16, 2005
Vol. 1, Iss. 6 Virtual Journal for Biomedical Optics
José M. Medina and José A. Díaz, "Postreceptoral chromatic-adaptation mechanisms in the red-green and blue-yellow systems using simple reaction times," J. Opt. Soc. Am. A 23, 993-1007 (2006)