Mind 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 THIS IS A PREVIEW. Buy this digital issue or subscribe to access the full article. Already a subscriber or purchased this issue? Sign In 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 A PREVIEW. Buy this digital issue or subscribe to access the full article. Already a subscriber or purchased this issue? Sign In Buy Digital Issue $5.99 Add To Cart Browse all subscription options! Subscribe 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.