Response functions for types of vision according to the Muller theory

~c.cording to the Muller theory of vision there a re t hree stages in t he visual process, an Imtlal photochemical stage, an intermediate chemical stage relating to t he chromatic aspect, and a fin al stage of excitations of the optic-nerve fib ers. By taking advantage of recent precise information r egarding the m etamer s characteristic of normal, protanopic, and deuteranopic vision t h re have been derived t he sp ectral variations of t he responses for each stage as function s of wavelength. These respon se function s account precisely for t he sam e normal m etamers as the l e I standard observer, and closely for t he same confusions by color-blind observers as t he simpler K on ig theory. Furthermore t hese fu nctions describe chrom atic t hresholds of the normal eye (Abney, Priest-Brickwedde) a s a gradual approach t o t ritano)Jic vision as fi eld size and luminance are decreased.