Color Signal Systems for the Red-Green Color Blind* An Experimental Test of the Three-Color Signal System Proposed by Judd

An experimental investigation is made of Judd’s proposed three-color code for instrument panel lights. The adequacy of these specifications is tested using both normal and color-deficient subjects. It is shown that if certain specific limiting conditions are met as to the luminance, subtense, and chromaticity of the light signals, all normal observers and a majority of color-deficient observers can make the necessary identifications. The possible explanations for the poor performance of some, but not all, protanopes are discussed.