Temporal responses to chromatic and achromatic change inferred from temporal double-pulse integration

Abstract

Temporal integration properties of two pulses were measured for both chromatic and achromatic changes with stimulus-onset asynchronies (SOA’s) of 20–2000 ms. The chromatic changes were made with respect to a reference white in both the red and the green directions by mixing 500- and 630-nm monochromatic lights at isoluminance. The achromatic changes were produced with luminance increments and decrements of the white light. In the condition of two-red (or two-green) pulse integration, a monophasic (excitatory) chromatic response was inferred, whereas in the condition of red-and-green pulse integration, a biphasic (excitatory and inhibitory) chromatic response was inferred. A biphasic achromatic response describes the results obtained in the increment-and-decrement pulse integration, and a triphasic achromatic response describes the data in two-increment (or two-decrement) pulse integration. Furthermore, it was shown that small stimulus fields of 3.4′ could affect achromatic integration but not chromatic integration. We derived chromatic and achromatic impulse response functions by using a three-level color-vision model.