The Eyes Have It

Eye gaze is critically important to social primates such as humans. Maybe that is why illusions involving eyes are so compelling

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The eyes are the window to the soul. That is why we ask people to look us in the eye and tell us the truth. Or why we get worried when someone gives us the evil eye or has a wandering eye. Our language is full of expressions that refer to where people are looking—particularly if they happen to be looking in our direction.

As social primates, humans are keenly interested in determining the direction of gaze of other humans. It is important for evaluating their intentions and critical for forming bonds and negotiating relationships. Lovers stare for long stretches into each other's eyes, and infants focus intently on the eyes of their parents. Even very young babies look at simple representations of faces for longer than they look at similar cartoonish faces in which the eyes and other features have been scrambled.

In this article, we investigate a series of illusions that take advantage of the way the brain processes eyes and gaze. It turns out that it is fairly easy to trick us into thinking that someone is looking somewhere else.

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 Special Editions Vol 22 Issue 3sThis article was published with the title “The Eyes Have It” in SA Special Editions Vol. 22 No. 3s (), p. 66
doi:10.1038/scientificamericanillusions0913-66

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