Step Into an Optical Illusion

n Demon Hill, the rules of gravity don't apply as you expect them to. Down is not down, exactly. The room, created by Los Angeles artist Julian Hoeber and on display at the Harris Lieberman Gallery in New York, is modeled on a stock roadside attraction, Hoeber says, and based on a simple trick. The room is tilted on a compound angle. The result is disorienting and highly popular -- drawing about 20,000 people when it appeared in L.A. Michael Landy, professor of neural science and psychology at New York University, explains how the piece creates a battle between our senses, and why the illusion is so strong.