These Skulls Look Purple and Orange, But They’re Not

If a sign tells you to follow the purple skull to your destination, the answer seems simple: go left. Follow the orange skull and you’ll go right. However, if you isolate the stripes that make up the skulls, you’ll find that you don’t see purple or orange. In fact, all of the stripes are the same color and if you look between them, you’ll see two red skulls. The pigments morph because of the ­Munker-​White illusion, which shifts the perception of two identical color tones when they’re placed against different surrounding hues. It’s called the “color-completion effect.” The phenomenon causes an image to skew toward the color of the objects that surround it. In a black-and-white image, a gray element would appear lighter when it’s striped with white, and darker when banded with black.