Content - Illusionary Contrast Ring

Illusionary Contrast Ring

Look at the figure below from a reasonable distance (not close to). Which side of the ring appears lighter?

Use the mouse to move the pencil out of the way. You now see that the circle has a uniform brightness. (You might need to set your screen brightness to maximum to see the effect.)


What's going on?

The experiment with the ring shows that the perception of brightness is influenced by the surrounding areas. We perceive a gray surrounded by black as being more light. Contrarily, gray surrounded by white seems to be darker.

The pencil, dividing the ring in the middle, increases the effect because it allows to see the ring as being made of two halves of different shades.