This special issue, 169 Best Illusions, contains a smorgasbord of static images that appear to be moving (such as the Hatpin Urchin shown here), “impossible” sculptures, freaky faces, ghostly afterimages and even some edible illusions.

Illusions make great eye candy, but they also serve a serious purpose. When we look at an illusion, we “see” something that does not match the physical reality of the world around us. Scientists take advantage of this discrepancy between perception and reality to gain insights into how our eyes and brains gather and interpret (or misinterpret) visual information. Here’s a sneak peek at 10 different types of illusions and what they reveal.

If you're near Naples, Fla., on May 10, head on over to the Naples Philharmonic Center for the Arts, where the 2010 Best Illusion of the Year Contest Gala will be held starting at 5 PM (Scientific American is a media sponsor). Here, the top 10 illusionists will present their creations and the attendees of the event will vote to pick the top three winners!