Mind & Brain See Inside Illusions That Play Hide-and-Seek with Perception Hidden illusions are the Easter eggs of the mind By Stephen L. Macknik and Susana Martinez-Conde MISSING THE FACE FOR THE TREE Mexican artist Octavio Ocampo's “metamorphic” paintings are rarely what they seem at first sight. OCTAVIO OCAMPO Visions Fine Art *Editor's Note - Please download PDF to view Illusions. He never once thought it probable, or possible, that the Minister had deposited the letter immediately beneath the nose of the whole world, by way of best preventing any portion of that world from perceiving it. This is only a preview. Get the rest of this article now! Select an option below: Buy Digital Issue Customer Sign In *You must have purchased this issue or have a qualifying subscription to access this content It has been identified that the institution you are trying to access this article from has institutional site license access to Scientific American on nature.com. Click here to access this article in its entirety through site license access. ADVERTISEMENT Scientific American is a trademark of Scientific American, Inc., used with permission © 2015 Scientific American, a Division of Nature America, Inc. All Rights Reserved.