Temporal integration of chromatic double pulses for detection of equal-luminance wavelength changes

Detection probabilities for wavelength changes were measured as functions of stimulus onset asynchrony (SOA) with the chromatic double-pulse method. Two test stimuli of a wavelength lambda t were successively exchanged with a reference stimulus of a wavelength lambda r in equal luminance for a short duration with a SOA. Durations were 5 and 50 msec, and the SOA varied between 5 or 50 and 2000 msec. Lambda r's were 571 and 518 nm, chosen from wavelengths near unique yellow and unique green so that wavelength difference delta lambda = lambda t - lambda r was perceived mainly as redness and greeness for lambda r = 571 nm and yellowness and blueness for lambda r = 518 nm. The results showed that temporal integration characteristics for these equal-luminance wavelength changes were quite consistent: complete integration with SOA up to 20 msec, partial integration with SOA between 20 and 200 msec, and probability integration with SOA greater than 200 msec. They did not show any inhibitory integration that was found for luminance changes.