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Why watching "Avatar" can feel like eating bad mushrooms

Brian Alexander writes:

The aliens in "Avatar" may be blue, but some moviegoers feel green after watching it.

The stunning 3-D technology featured in "Avatar" is undoubtedly crucial to the sci-fi epic's nine Academy Award nominations (including Best Picture) and speedy rise to become the world's highest-grossing film worldwide. But despite its phenomenal popularity, not everybody has "3-D ready" eyes. A big group of people around the world have reported feeling nausea, dizziness and other ill effects while watching the film in 3-D. Others are stereoblind, that is, they don't see properly out of both eyes – or are missing an eye, because of cancer, say — and can't enjoy the effects of the state-of-the-art digital technology.

And if you got sick during "Avatar," forget about going to see the 3-D versions of "Alice in Wonderland" (opening on March 5), "Clash of the Titans" or the next "Harry Potter" movies.

A variety of visual and neurological conditions can cause someone to experience nausea and headache while watching a movie in 3-D, especially a group of disorders related to the body's vestibular system — the network of nerves, fluids and canals in the ear that connect to the brain and help us keep our balance and orient ourselves in space. About 35 to 40 percent of adults over age 40 have some sort of vestibular problems, according to Lisa Haven, executive director of the Vestibular Disorders Association, who says she has trouble herself. She hasn't seen "Avatar." "I think about it with trepidation," she said.

But even younger folks who have never been diagnosed with a dysfunction in the inner ear could experience a kind of motion sickness while watching 3-D, experts say.

A 3-D image creates an illusion of depth when the brain fuses two, slightly different 2-D images as they are projected on the movie screen, one perceived by each eye. This is called binocular disparity.

We need 3-D glasses to provide each eye with its version of the image. The glasses are worn very close to our eyes and the lenses of our eyes want to focus on this close-in image, but the binocular disparity is telling our brains that the image is further away.

Two researchers, Frederick Bonato and Andrea Bubka of St. Peter's College in Jersey City, N.J. call the problem "sensory conflict."  Because our eyes are central to helping our vestibular system keep us oriented (try spinning with your eyes closed), the conflict creates confusion and "the brain can be tricked into thinking the body has been poisoned," says Bonato, editor-in-chief of the journal Aviation, Space and Environmental Medicine.

That may sound off the wall, but when we are poisoned we often get nauseous so we can expel whatever is poisoning us. Of course, the 3-D technology isn't literally poisoning us, but the conflicting sensory input can seem similar to the effects of, say, bad mushrooms, and so our brain communicates along the vagus nerve and tells us to throw up.
Bubka felt this effect for herself when she went to Avatar. "We both saw Avatar and I felt a little sick, though Frederick did not," she said. "There is a lot of variability among people."

Diseases like multiple sclerosis, and Meniere's Disease (which appears to have several possible causes) and something called BPPV or benign paroxysmal positional vertigo – which can be caused by ear infections, trauma, toxins and other insults – are common reasons why people suffer from vestibular dysfunction.

Others are sharing their problems relating to Hollywood's 3-D juggernaut. "My friends and I all went and saw Avatar," one poster on a SomethingAwful.com forum wrote. "During the movie my eyes felt like they were going to pop and my head was splitting and I felt a little sick. During the movie about 15 people walked out."

Many people do learn to compensate for inner ear problems by relying on their eyes and their neuromuscular system to feed accurate information to the brain. But when the eyes are being fed conflicting information by 3-D, they can't, explained Patricia A. Winkler, professor emeritus at Regis University in Denver and a clinician who works with people suffering from vestibular dysfunction.

"So you are sitting in a movie theater, sitting still, and your muscles say 'No, you are not moving,'" she explained. "And your inner ear system says there's no fluid movement. But your visual system says 'Lots of things are moving out there and in 3-D' like what you see in everyday life. That's powerful because that 3-D flow on your retina tells you 'Yes, I am moving' and it is easy to believe your visual system because in humans, that is a high priority sensory system."

In other words, it's like getting carsick or seasick in a movie theater. There are rehabilitative therapies for extreme cases of vestibular dysfunction that can help those at risk for frequent falls, broken bones, and difficulties driving, for example. But for those with milder cases, the best solution for 3-D movie queasiness may be to stick with the 2-D version.

At least then you won't have to spend two hours wearing goofy glasses.