Detection of long-duration, long-wavelength incremental flashes by a chromatically coded pathway.

Abatwt-This paper reports tests of the hypothesis that a 200 msec 667 nm, fovea1 test Rash, presented upon a steady, 8” background, is detected by a pathway whose sensitivity is monotonically related to a Iinear functional of photoreceptor quantum catch. The measurement conditions used in this paper are the same as those used by Stiles in his n-mechanism analysis. The hypothesis is tested by measuring increment-threshold curves for various background wavelengths and for various mixtures of two backgrounds. The results clearly reject the hypothesis. We propose two models that are consistent with the mcasurements reported here as well as measurements-using a 10 msec test flash-reported previously. We then discuss related empirical and theoretical work.