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A Stereoscopic Journey

By September 9, 2009Newswires

A Stereoscopic Journey
Mount Holyoke professor Susan Barry`s book explores her attempt to learn to see in a whole new way.
By James Heflin

Imagine, if you can, seeing in only two dimensions, as if everything appeared on a screen. Almost all of us, of course, see in three, and don`t give depth perception much thought.

You can simulate two-dimensional vision to some degree by merely closing one eye. Nothing seems different at first, used as you probably are to judging distance from visual cues with both eyes. Yet something weird happens if you try something like dropping a paper clip into the top of a bottle a couple of feet away.

Yes, your hand looks smaller as you move it farther from your body, but you may well miss the bottle anyway. That`s because your brain is used to relying on binocular vision, which is to say your eyes are on either side of your nose, and your brain processes the left and right eye images by mixing them into one, providing a sense of distance—or three-dimensionality.

Mount Holyoke professor (and neurobiologist) Susan Barry didn`t realize she lacked stereo vision until she was in college. When Barry was an infant, her eyes crossed—when she focused on something with either eye, the other turned inward. This led to a series of surgeries to realign her eyes. Both eyes then functioned properly on their own, but the two still did not function together to provide stereo vision; her brain suppressed one of the two images coming from her eyes instead of integrating the two. This problem wasn`t really apparent to anyone when Barry was a child in the 1950s—her doctor merely told her parents her depth perception wasn`t good.

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