NATIONAL GEOGRAPHIC BRAIN GAMES
'The top & bottom hues <a href="http://www.j-archive.com/media/2011-10-07_J_26.jpg" target="_blank">here</a> are the same; the brain <a href="http://www.j-archive.com/media/2011-10-07_J_26a.jpg" target="_blank">tricks itself</a> by using <a href="http://www.j-archive.com/media/2011-10-07_J_26b.jpg" target="_blank">these</a> areas of comparative darkness as cues'
shadows