Aging and the saturation of colors. 2. Scaling of color appearance

Saturation of two sets of stimuli was scaled by 21 color-normal observers ( ten younger and 11 older observers, mean ages: 30 and 73 years). Circular f ields, 1.2 degrees in diameter, were presented in Maxwellian View as 1.5-s flashes with 3-s interstimulus intervals. Stimuli were mixtures of broadban d light [CIE(x,y) = (0.35, 0.39), 200 trolands (td)] and monochromatic Ligh t (420-700 nm, 50 td). Monochromatic Lights were equated by the 1978 2 degr ees fundamental observer's luminosity function in one set of stimuli [J. J. Vos, Color Res. Appl. 3, 125 (1978)] and by each observer's heterochromati c flicker photometry function in the other set of stimuli. Comparing the tw o age groups reveals no sizable differences in saturation for either set of stimuli, neither supporting nor refuting neural compensation for age-relat ed increases in ocular media density (OMD). Examining short-wavelength satu ration as a continuous function of estimated OMD reveals a more complicated pattern of results, however, suggesting substantial compensation over a ce rtain range of OMD Values but incomplete compensation for observers with th e highest OMD values. (C) 1999 Optical Society of America [S0740-3232(99)02 202-4].