A well-known phenomenon to cat owners is the tendency of their cats to sit in enclosed spaces such as boxes, laundry baskets, and even shape outlines taped on the floor. A new study asks whether domestic cats are also susceptible to sitting in enclosures that are illusory in nature, utilizing cats' attraction to box-like spaces to assess their perception of the Kanizsa square visual illusion. "It's truly mystifying," says Gita Gnanadesikan, an animal-behavior researcher at the University of Arizona who fosters undersocialized cats.