Prediction of transparency perception based on cone-excitation ratios.

Perceptual transparency was measured in two experiments by using simulations of illuminated surfaces presented on a CRT monitor. In a two-alternative forced-choice paradigm, observers viewed two simulated Mondrians in temporal sequence. In one sequence the Mondrian was simulated to be partially covered by a transparent filter; in the other sequence the filter color over each Mondrian patch was modified. Observers were instructed to select the sequence containing a transparent filter. Observers' selections corresponded to sequences in which the cone-excitation ratios for each adjacent pair of Mondrian patches were approximately the same as the cone-excitation ratios for the pair of patches covered by a filter. The results suggest that cone-excitation ratios may be a cue for perceptual transparency.