
PERCEPTUAL ILLUSIONS Leaning toward the image makes it appear as if it is bulging.

The radiating lines trick the brain into perceiving motion forward, so the center appears to bulge.
Staring at a pattern meant to evoke an optical illusion is usually an act of idle curiosity, akin to palm reading or astrology. The dot disappears, or it doesn’t. The silhouette of the dancer spins clockwise or counterclockwise. The three-dimensional face materializes or not, and the explanation always seems to have something to do with the eye or creativity or even personality.