Page "Hermann Ebbinghaus" Paragraph 16

The Ebbinghaus Illusion.

Note that the orange circles appear of different sizes, even though equal.

Ebbinghaus is also credited with discovering an optical illusion now known after its discoverer — the Ebbinghaus illusion, which is an illusion of relative size perception.

In the best-known version of this illusion, two circles of identical size are placed near to each other and one is surrounded by large circles while the other is surrounded by small circles ; the first central circle then appears smaller than the second central circle.

This illusion is now used extensively in research in cognitive psychology, to find out more about the various perception pathways in our brain.