Stochastic independence of color-vision mechanisms confirmed by a subthreshold summation paradigm

We have used a subthreshold summation protocol to analyze spatial color-col or interaction. By means of a CRT color monitor, rye measured the threshold contours for a spatial frequency of 0.5 cycles/degree. Heterochromatic fli cker photometry was used to obtain isoluminance. The results suggest that t he blue-yellow (b-y) and red-green (r-g) contrast thresholds remained uncha nged by the addition of fixed r-g and b-y subthreshold pedestals. Our subth reshold summation data then support the stochastic independence of color-vi sion mechanisms derived from Mullen and Sankeralli's work [Vision Res. 39, 733 (1999)] despite the differences that exist between the two experimental methods. (C) 2000 Optical Society of America [S0740-3232(00)01707-5].