Pinna Illusion
Is something moving here—or isn’t it?
Although the image is completely still, the circles seem to rotate. The effect is caused by how the brain processes contrast and tiny eye movements.
The Science Behind It
The image consists of repeating patterns with strong differences in brightness and contrast. Your eyes process light and dark areas at different speeds. Especially during small, unconscious eye movements, this creates timing differences in the brain. These are interpreted as motion even though the image is static. This illusion is known as the Pinna illusion. It shows that the brain does not directly measure movement, but calculates it from changes in an image. Even tiny differences in brightness and contrast can create the impression of rotation. The result is movement without anything actually moving.
