Linear and nonlinear opponent color coding.

Presents data from 2 experiments with a total of 5 Ss which confirm the linearity axiom as proposed by D. H. Krantz (1975) for red/green equilibria, i.e., lights which appear neither reddish nor greenish (unique yellows, unique blues, and achromatic colors). Some evidence of "veiling" (i.e., the masking of a weak hue component by a strong one) was also obtained. Hue magnitude estimates (HME) for the green component were obtained in variable mixtures of unique green and unique yellow stimuli. The relation between the HME and the luminance of the green stimulus was not independent of the amount of added yellow. A relation proposed by T. Indow and S. S. Stevens (1966), in which the proportion of the green luminance is taken as the relevant psychophysical unit, gave a better fit to the data. It is shown, however, that alternative interpretations of such data are possible and that this experiment cannot be conclusive regarding the issue of the possibility of absolute judgment of opponent hue attributes.