10 Top Illusions

Balls that roll uphill, bathtubs that stretch and shrink, freaky faces and throbbing hearts. Welcome to the year's best visual tricks

Join Our Community of Science Lovers!

A Japanese miner climbs onto the stage, his helmet light bobbing and a pickax slung over his shoulder. He swings the pick a few times before kneeling to inspect something unusual and then worries at some loose rubble with his hands. Suddenly his face lights up, and he turns to the audience, his newfound riches held forward in his open hands. “I have discovered a new supermagnet that attracts wood,” he announces. Okaaaay....

A video begins playing overhead, and the audience sees four wood balls rolling uphill in open defiance of the laws of gravity. Pulled by a magnet? Not really. The “miner” is mathematical engineer Kokichi Sugihara of the Meiji Institute for Advanced Study of Mathematical Sciences in Kawasaki, Japan, and his magnetlike slopes illusion is the winner of the 2010 Best Illusion of the Year Contest. The trick is exposed when the video shows Sugihara’s slopes from a different vantage point: the wood balls are actually rolling down, not up. The slopes are cleverly designed to produce the antigravity illusion when seen from a specific point of view.

Sugihara’s invention exemplifies several of the most popular themes in illusions today. It relies not only on a trick of perspective but also on perceptual ambiguity. There is more than one way to perceive the “magnetic” slopes, but our visual system’s expectations make us prefer one interpretation—and illusions are a way to fool the brain into revealing those systems. “We are surrounded by many industrial products that are made with right angles, such as desks, boxes and buildings,” Sugihara explains. When confronted with an image in which multiple interpretations are possible, we choose the version that allows us to see rectangular solids. In Sugihara’s prizewinning illusion, none of the columns that support the ramps are vertical. Yet we interpret them all as perfectly straight.


On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.


As with many of the newest illusions, Sugihara’s impossible-motion demonstration is dynamic: to fully appreciate the magic, you need to see the balls moving. Although illusionists continue to produce classical illusions using still photographs or even just a few lines on paper, computer and video technologies have made it possible to create increasingly complex moving-picture illusions. Several of the top 10 illusions of 2010 are animations that cannot be shown here, but you can see them in action at http://illusionoftheyear.com.

Because illusions enable us to see things that do not match physical reality, they are critically important to understanding the neural mechanisms of perception and cognition. The annual Best Illusion of the Year Contest celebrates the inventiveness of illusion creators around the world: researchers, software engineers, mathematicians, magicians, graphic designers, sculptors and painters fascinated with mapping the boundaries of human perception.

Whereas scientists once created illusions from simple lines and shapes and artists focused on making eye-popping illusions, the overlap between science and art is now greater than ever. Scientists are using graphic-design tools to make their illusions more artistic, and artists have grown more knowledgeable about the neuroscience behind the magic.

Illusions competing in the contest must be novel—that is, previously unpublished or published no earlier than the year preceding the contest. An international panel of experts selects the 10 illusions that are the most counterintuitive, spectacular, beautiful and significant to the understanding of the human mind and brain. The creators are invited to present their awe-inspiring brain twisters at an awards gala where the audience votes to choose the first-, second- and third-place winners: the “Oscars” of illusion.

Anyone can submit an illusion to the contest, which is sponsored by Scientific American. Instructions are posted at http://illusionoftheyear.com/submission-instructions. The 2011 event is scheduled for Monday, May 9, at the Philharmonic Center for the Arts in Naples, Fla. Please join us and vote for the best illusion of the year!

Susana Martinez-Conde is a professor of ophthalmology, neurology, and physiology and pharmacology at SUNY Downstate Health Sciences University in Brooklyn, N.Y. She is author of the Prisma Prize–winning Sleights of Mind, along with Stephen Macknik and Sandra Blakeslee, and of Champions of Illusion, along with Stephen Macknik.

More by Susana Martinez-Conde

Stephen L. Macknik is a professor of opthalmology, neurology, and physiology and pharmacology at SUNY Downstate Medical Center in Brooklyn, N.Y. Along with Susana Martinez-Conde and Sandra Blakeslee, he is author of the Prisma Prize-winning Sleights of Mind. Their forthcoming book, Champions of Illusion, will be published by Scientific American/Farrar, Straus and Giroux.

More by Stephen L. Macknik
SA Mind Vol 22 Issue 2This article was published with the title “10 Top Illusions” in SA Mind Vol. 22 No. 2 (), p. 30
doi:10.1038/scientificamericanmind0511-30

It’s Time to Stand Up for Science

If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.

I’ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.

If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.

In return, you get essential news, captivating podcasts, brilliant infographics, can't-miss newsletters, must-watch videos, challenging games, and the science world's best writing and reporting. You can even gift someone a subscription.

There has never been a more important time for us to stand up and show why science matters. I hope you’ll support us in that mission.

Thank you,

David M. Ewalt, Editor in Chief, Scientific American

Subscribe