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 fields, 1.2 degrees in diameter, were presented in Maxwellian view as 1.5-s flashes with 3-s interstimulus intervals. Stimuli were mixtures of broadband light [CIE(x, y) = (0.35, 0.39), 200 trolands (td)] and monochromatic light (420-700 nm, 50 td). Monochromatic lights were equated by the 1978 2 degrees fundamental observer's luminosity function in one set of stimuli [J. J. Vos, Color Res. Appl. 3, 125 (1978) and by each observer's heterochromatic flicker photometry function in the other set of stimuli. Comparing the two age groups reveals no sizable differences in saturation for either set of stimuli, neither supporting nor refuting neural compensation for age-related increases in ocular media density (OMD). Examining short-wavelength saturation as a continuous function of estimated OMD reveals a more complicated pattern of results, however, suggesting substantial compensation over a certain range of OMD values but incomplete compensation for observers with the highest OMD values.