Their ability to distinguish between green and yellow was the next to go. It wasn't a matter of the colors themselves, but the contrast between them that seemed to spell which colors would fade. David Post, Chelette's co-researcher, said what makes the difference is the luminance contrast between two colors. Luminance contrast is a ratio of two luminances that measures how well something stands out against its background. The luminance contrasts that can be produced on a cockpit's display depend on the colors in use.
Displays produce color by mixing red, green, and blue light.
Green usually has the highest peak luminance and blue has the lowest. Displayed upon a dark gray background, for example, green symbols can be presented at higher contrast than blue symbols, making the green symbols less likely to fade than the blue ones. Centrifuge testing consisted of two experiments. In both tests, the subjects were first spun up to nine gs. For one experiment, the subjects were asked to identify colors as they appeared on a display screen.