Perceptual Constancies: Brightness Constancy

We perceive an object as having constant lightness even while its illumination varies. Perceived lightness depends on the amount of light an object reflects relative to its surroundings.


Snow will reflect more light during the day than the middle of the night, but you can still the snow is white during the night. Even though the brightness varies during the two times of the day, our eyes and brains recognize the snow as the same color.