The challenge
Place a small mirror vertically at the center of the image, perpendicular to the page. Look at the reflection combined with the other half of the image. Move the mirror slowly to the left and right. What kinds of faces do you see?
Objective
Explore binocular vision and the brain's automatic face-recognition system.
Materials
A small flat mirror (a compact mirror works well).
Description
This experiment plays with the brain's extraordinary ability to detect and construct faces. The fusiform face area (FFA), a region of the temporal lobe, activates automatically when any face-like pattern appears. This system evolved for survival — quickly recognizing friend from foe — but it also explains why we see faces in clouds, wood grain, and toast.