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Stereo 3D devices can be such a headache--literally

A study out of Berkeley finds that a phenomenon called vergence-accommodation--focusing on both the distance to a screen and the content in front of or behind that screen--can lead to discomfort, fatigue, and headaches.

If you've ever watched stereo 3D on your smartphone and found yourself rubbing your temples, you're not alone.

Time for a Tylenol? Inha Lee Hale/Flickr

New research out of U.C. Berkeley suggests that eyestrain and the ensuing discomfort is the result of a phenomenon called the vergence-accommodation conflict, by which the eyes have to manage both watching a screen at a certain distance and simultaneously making sense of images that are either in front of or behind that screen.

"When watching stereo 3D displays, the eyes must focus--that is, accommodate--to the distance of the screen because that's where the light comes from; and at the same time, the eyes must converge to the distance of the stereo content, which may be in front of or behind the screen," says Martin S. Banks, the professor of optometry and vision science at Berkeley who published the report in today's Journal of Vision.

Though his series of experiments was conducted on just 24 adults, a sort of discomfort trend emerged: Watching stereo content in front of the screen (which appears to jump into the viewer's space) was less comfortable from a shorter distance more typical with cell phones and laptops, while stereo content placed behind the screen (appearing as though the viewer is peering through a window) was less comfortable when viewed at greater distances more common in movie theaters.

Banks suggests that more studies be conducted across larger sample sizes that include children, and that those pave the way for actual guidelines on appropriate viewing distances.

"This is an area of research where basic science meets application, and we hope that the science can proceed quickly enough to keep up with the increasingly wide use of the technology," he says.