Optical Illusion

Motion Magic

The Brain Looks Forward

Optical illusions may fool the brain because it is trying to predict the future.

The brain takes nearly one tenth of a second to consciously register a scene. But the scenery changes far more quickly than that when we move. How does our brain cope? By constantly predicting the future, posits Mark Changizi, now at the Rensselaer Polytechnic Institute. This ability explains many visual illusions—look here, for example, as you move this page toward and away from you. The extra motion results from your brain estimating where the ellipses will be in several milliseconds, Changizi says. He and his colleagues explain this illusion and 50 others in April’s Cognitive Science.

—Lucas Laursen