Abney effect

The Abney effect describes the perceived hue shift that occurs when white light is added to a monochromatic light source.

The addition of white light will cause a desaturation of the monochromatic source, as perceived by the human eye. However, a less intuitive effect of the white light addition that is perceived by the human eye is the change in the apparent hue. This hue shift is physiological rather than physical in nature.