If you look at a sheet of white paper in a dim room and then look at it in bright sunlight, the paper will reflect more light to the eye when you are outside than inside. Yet we see the paper as having the same lightness in both situations. Why?
A) the brain adjusts for our memory of the lightness of the paper
B) the brain makes the assumption that lightness does not change with location
C) the brain uses the paper/surround intensity ratio in both locations
D) the brain adjusts the perception of the lightness of the paper

Question

Quizplus · Accepted Answer

The brain uses the paper/surround intensity ratio in both locations to judge the lightness of the paper. This is known as the lightness constancy phenomenon, where the brain adjusts the perception of lightness based on the brightness of the surrounding environment. Therefore, even though the amount of light reflected by the paper changes between dim and bright environments, we still perceive the paper as having the same lightness due to our brain's adjustment.

If You Look at a Sheet of White Paper in a Dim