Do you ever want to change the way you see the world? Wouldn't it be fun to hallucinate on your lunch break? Although we typically associate such phenomena with powerful drugs like LSD or mescaline, it's easy to fling open the doors of perception without them: All it takes is a basic understanding of how the mind works. Much of what we think of as being out there actually comes from in here, and is a byproduct of how the brain processes sensation. In recent years scientists have come up with a number of simple tricks that expose the artifice of our senses, so that we end up perceiving what we know isn't real. [Examples include:] The Ganzfield Procedure: Begin by turning the radio to a station playing static. Then lie down on the couch and tape a pair of halved ping-pong balls over your eyes. Within minutes, you should begin to experience a bizarre set of sensory distortions. Purkinje Lights: Jan Purkinje, a founding father of modern neuroscience stumbled upon a reliable hallucination as a child. First he closed his eyes (very important!), then tilted his head to face the sun and moved his hand quickly back and foth in front of his closed eyes. After a few seconds, Purkinje reported the appearance of beautiful figures," which gradually became more intricate. The hallucinations are a side effect of our need to always make sense of reality.