Effect of the short-wavelength-sensitive-cone mosaic and rods on the locusof unique green

A primary goal of this study was to establish whether the magnitude of the short-wavelength-senuitive- (S-) cone signal into the yellow/blue (Y/B) mec hanism was influenced by the absolute or the relative numbers of S cones. T his was assessed by measuring the locus of unique green for various test si zes at four eccentric locations chosen to exploit differences in the underl ying mosaic of S cones. In general, the locus of unique green was unaffecte d by test size, retinal quadrant, or rod input but was influenced by retina l eccentricity. The locus of unique green shifted to shorter wavelengths as retinal eccentricity increased from 1 degrees to 8 degrees. The data do no t support a model whereby the S-cone signal is determined by the absolute n umber of S cones, but a model based on the relative number of S cones canno t be eliminated. (C) 2000 Optical Society of America [S0740-3232(00)00901-7 ].