The Disappearing Face

In this display, you can "erase" the face of the visitor sitting across from you, just as if he were using a pencil eraser.

As you look at the scene before you, different pictures are being sent to each of your eyes. One eye sees your partner's face, and the other sees a blank wall reflected in the mirror. When two different pictures compete, the brain chooses the more interesting one.

In the competition between your partner's face and the blank wall, the face wins. But when you add movement, it captures the brain's attention, and we perceive a combined image from the left and the right. Part of our partner's face seems to vanish.

This illusion is another example of binocular rivalry - the competition between two different inputs coming from our eyes. In this illusion, however, our eyes see stimuli that are not equally interesting. Therefore, the brain does not treat the two stimuli equally, and our perception does not switch evenly between the two. When one visitor waves his hand, it is the movement that attracts our attention. This becomes the dominant stimulus, while the face remains static.

It is usually only the eyes and nose that get "erased", with only the mouth remaining visible. That's why this illusion is also called the Cheshire Cat illusion, just like the famous feline in Alice in Wonderland.

Some people say it's harder to "erase" a face that belongs to someone you love. Try it yourself!

Related exhibit:
Tournament of the Eyes - Right vs. Left