People with color-deficient vision for red and green may still see yellow. This is most easily explained by

Question

Quizplus · Accepted Answer

The opponent-process theory suggests that color vision is based on three pairs of opposing colors: red versus green, blue versus yellow, and black versus white. People with color-deficient vision for red and green may still see yellow because the opponent process between blue and yellow is not affected.

People with Color-Deficient Vision for Red and Green May Still