The science of motion sickness

When he began his research on motion sickness, Tom Stoffregen thought finding test subjects would be difficult. After all, it’s called motion sickness because it results in headaches, dizziness, and, often, literally being sick. What kind of people would be eager to find out what it takes to make them throw up?

U students, it turns out. A lot of them.

“Undergraduate students, as a class, are suicidal,” Stoffregen says bluntly. “I’m flooded with volunteers.” He suspects the mass offering of students may have something to do with misplaced pride. “People think, ‘You can’t make me throw up,'” he says. Unfortunately for them, Stoffregen, a professor in the College of Education and Human Development’s School of Kinesiology, has invested a lot of time and effort into finding out exactly what brings on motion sickness. And, like an academic 007, he’s got a license to test.

Stoffregen’s interest in motion sickness goes back to his childhood, when he was interested in space flight. He knew some astronauts suffered motion sickness, and after studying motion in graduate school and working for NASA, he wanted to find out why.

People have been motion sick for thousands of years, says Stoffregen, conjuring visions of dizzy Neanderthals and green-faced Vikings, but no one is sure why.

“There’s an intuitive assumption that motion sickness is caused by the inner ear,” he says. So far, the only approach to the problem has been studying how the sensations in the inner ear and eyes are different in situations when motion sickness results. For example, when a person is in a car and the eyes report movement but the body thinks it’s stationary. Stoffregen thinks, however, that these perceptual differences are not what causes motion sickness. After all, nearly every person on this planet has experienced those perceptual differences at some point or another, and if we all reacted by being motion sick, well, let’s just say the world would be a much different place. We’d have to take pilgrimages instead of planes, for one thing, and the rides at Disneyland would become the stuff of children’s nightmares.

But if perceptual differences are not the cause of motion sickness, then what is? Movement, says Stoffregen. He measures the movement of people subjected to his sickness-inducing tests, and “the people who are going to get sick commence to move in really weird ways,” he says, imitating the type of staggering walk typical after tequila night at the bar. Even when the subjects are strapped to an upright stretcher, the ones who feel sick still move a little. “They wriggle,” says Stoffregen. Due to individual differences to sensitivity, only about half of Stoffregen’s test subjects feel sick. Those who don’t also don’t wriggle, which makes Stoffregen think that movement is the key factor behind motion sickness.

Stoffregen has tested his theory extensively in the University’s Human Factors Research Laboratory. His tests are all designed to make a person feel motion sick, but the test subjects remain stationary while the scenery around them shifts. In one test, a room-like structure is set on metal tracks. The subject stands on a platform as the “room,” which has three walls and a ceiling, slides forward and backward on the tracks. The effect of the moving room has also been computerized, so a subject can stand in front of a huge screen and feel the same effects. Stoffregen also has an Xbox in his lab, which he asks test subjects to play. He doesn’t even need special games. “The games are so realistic now, they can make people sick,” he explains.

Being an undergraduate myself (though not suicidal) it only seemed right to undergo one test. Stoffregen directed me to the moving room, where he placed a two-by-four board on the platform before standing me on it. An inch of my flip-flops extended past each edge of the two-by-four, placing me just slightly off-balance. The décor was hurl-worthy on its own: The walls and ceiling were covered in white wallpaper veined with blue, giving the room the air of a huge marble crypt, and the focal piece was a bland map of the United States that only added to the atmosphere.

Stoffregen told me to focus on the map, then pulled the room backward a few feet. The map came zooming at my face, and it felt as if the floor had tilted backward 45 degrees. I took an involuntary step back (off the two-by-four), certain that I would fall over otherwise. Test subjects often endure 30 to 40 minutes of this, Stoffregen said, but 30 seconds was enough for me. No macho pride here; I fully believed he could make me toss my cookies.

Interestingly enough, Stoffregen says that no one knows why motion sickness often results in nausea and vomiting. As yet there is no scientific explanatinon for why seasickness makes you spew, carsickness makes you blow chunks, roller coasters make you ralph, or transoceanic flights to Osaka will make your stomach say sayonara to that sushi.

But despite undergoing tests designed to make people sick, no participants have ever actually done the technicolor yawn in the lab.

“We’re interested in how [motion sickness] begins, not how it ends,” Stoffregen says. “No on has ever thrown up in my lab. And that’s a record I’m proud to keep.”

From University of Minnesota

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