The Simultaneous Contrast Illusion is an optical illusion that occurs when two different colors are placed side by side. The colors appear to interact with each other, creating a contrast that is greater than what would be expected. This illusion is caused by the brain's perception of the colors, as it
From Wikipedia
A contrast effect is the enhancement or diminishment, relative to normal, of perception, cognition or related performance as a result of successive or simultaneous exposure to a stimulus of lesser or greater value in the same dimension.