This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
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To experience this illusion you will need a cardboard tube, such as from a kitchen paper towel roll or a poster tube. Look through the tube with one eye, keeping the other eye open. While still looking, point the tube at a bright wall. After just a few seconds, the circle seen from the tube will look much brighter than the rest of the wall! You can also look at a textured surface, where the illusion will enhance not only the brightness and color, but also the details in the pattern. This phenomenon, discovered by Lothar Spillmann, Joe Hardy, Peter Delahunt, Baingio Pinna, and John Werner, competed as a Top Ten finalist in the 2009 Best Illusion of the Year Contest. Its neural bases are not currently understood.
