In an impossible figure, seemingly real objects—or parts of objects—form geometrical relations that physically cannot happen. The artist M.C. Escher, for instance, depicted reversible staircases and perpetually flowing streams, whereas mathematical physicist Roger Penrose drew his famously impossible triangle and visual scientist Dejan TodoroviTodorovi created an Elusive Arch that won him Third Prize of the 2005 Best Visual Illusion of the Year Contest. These effects challenge our hard-earned perception that the world around us follows certain, inviolable rules. They also reveal that our brains construct the feeling of a global percept, “or individual item we perceive,” by sewing together multiple local percepts. As long as the local relation between surfaces and objects follow the rules of nature, our brains don’t seem to mind that the global percept is impossible.

Several contemporary sculptors recently have taken up the challenge of creating impossible art. That is, they are interested in shaping real-world 3-D objects that nevertheless appear to be impossible. Unlike classic monuments – think of the Lincoln monument - which can be perceived by either sight or touch, impossible sculptures can only be interpreted (or misinterpreted, as the case may be) by the visual mind. All of the accompanying slides show real objects. No photographic manipulation has been used.

Slide Show: Impossible Sculptures

Are you a scientist? Have you recently read a peer-reviewed paper that you want to write about? Then contact Mind Matters editor Jonah Lehrer, the science writer behind the blog The Frontal Cortex and the book Proust Was a Neuroscientist. His next book, How We Decide, will be available in February 2009.

ABOUT THE AUTHOR(S)

Stephen L. Macknik is director of the Laboratory of Behavioral Neurophysiology at the Barrow Neurological Institute and earned a Ph.D. in neurobiology from Harvard University. Susana Martinez-Conde is director of the Laboratory of Visual Neuroscience at the Barrow Neurological Institute in Phoenix. She holds a Ph.D. in medicine and surgery from the University of Santiago de Compostela in Spain.