Made of crude materials, the small chamber consists of three large textured walls, one with a map of the United States fixed to it. During his studies, Prof. Thomas Stoffregen, director of the U’s Affordance Perception-Action Laboratory, invites visitors to step onto a sensor inside the chamber. Suddenly, one of the walls zooms forward, forcing the test subject off balance.

Here, in this humble lab in the landlocked Midwest, Stoff­regen has come up with a theory he hopes will turn what we know about motion sickness on its ear.

Scientists have long believed that the source of motion sickness lies inside the body — the inner ear, known as the organ of balance.

Stoffregen suggests otherwise.

He contends that when we enter a challenging environment — be it a boat, a roller coaster or the back seat of a car — it’s poor posture control that causes us to get sick.

Our bodies are constantly swaying, whether we’re conscious of it or not, he said. It’s when we sway too much and lose our balance that motion sickness sets in.

“The way that you sway is predictive of whether you’re susceptible to motion sickness,” Stoffregen said.

This approach to understanding motion sickness — affecting at least a third of the population — has won some support from fellow researchers, but it’s taken some time to gain acceptance.

“His theory is original. It’s innovative,” said Robert C. Kennedy, an adjunct psychology professor at the University of Central Florida. “It’s a different way of looking at motion sickness.”

Michael Waak, 24, says he’s “notorious” among his friends for getting queasy. A graduate student at the University of Minnesota, he says his stomach often turns when he walks up flights of stairs or when he’s on an elevator. He carries Dramamine in his backpack at all times. When he rides in a car, he makes sure to eat something beforehand, and he prefers to drive.

“It’s difficult,” he said. “People get impatient with me or think I’m making it up as some kind of excuse to avoid certain situations or activities.”

Waak said he’s convinced that his queasiness is tied to his inner ear. When he went to Europe for a month, he wore a motion sickness patch behind his ear that released medicine to numb the feeling of motion.

One of the reasons so many people buy into the traditional theories on motion sickness is because those ideas seem very intuitive, Stoffregen said. He doesn’t dispute the fact that people boarding a ship, for example, will experience changes in their inner ear.

“But that doesn’t mean those are the only things that can cause what’s going on there,” he said. Being on a ship forces people to control their body differently, he said. “You have to get your sea legs.”

The same is true for experiments conducted in his moving room, which has been around more than a decade.

Unlike the first moving room built in Scotland in 1972, which had walls that were moved by hand, the U’s version is mounted on wheels that travel back and forth on rails, which are controlled by a computer. The computer can be programmed to vary how far and how fast the walls move, allowing researchers to create unpredictable movement patterns, similar to, say, a ship bobbing in the waves.

In the chamber, people are tested for up to 40 minutes, while data about their “body sway” are collected. The results consistently show that body posture and movement strongly predict whether a person is prone to motion sickness, Stoffregen said. “If I look at your sway, I can make a better estimate of your susceptibility than you can,” he said.

In the past, motion sickness was studied almost exclusively by physicians, as ship doctors searched for a medical explanation for the phenomenon. It’s been only in the past 40 years, Stoffregen said, that there are people studying motion sickness from a nonmedical perspective.

Now that realistic digital devices are adding new triggers for inducing motion sickness, more people from various disciplines are studying it. Video games have become more realistic, as they immerse players in a quasi-virtual reality.

“Nobody ever got sick from playing Pac-Man,” Stoffregen said, who has also done studies on video games and their connection to motion sickness.

More recently, complaints have surfaced about the iPhone’s latest operating system causing some people to feel dizzy and nauseated from its 3D-like effects.

The search for relief

Stoffregen’s theory might be getting more recognition these days, but for years it was dismissed or ignored, in part because it came from Minnesota. Stoffregen first published his theory in 1991.

“Sea sickness has been the dominant driving force for the study of this,” Kennedy said.

Courtney Freese, of Minneapolis, shudders at the thought of Stoffregen’s moving room, but she says she’d love to understand her motion sickness better.

When she was younger, motion sickness didn’t seem to affect her. Now the 23-year-old can’t ride roller coasters without feeling queasy. She also gets dizzy from watching movies on the giant Imax screen.

“That was a nightmare!” she said, recalling the last time she went to a movie. “I spent the majority of it looking down at the floor, listening to it but not actually watching the movie.”

If Stoffregen is right, then his research could spawn further studies to develop better ways to prevent the onset of motion sickness — instead of having to treat the subsequent dizziness and nausea. “What we have learned is there is a relationship between the way you perceive and control the motion of your own body and your propensity to get sick,” Stoffregen said.

For now, Freese keeps track of her symptoms and is always looking for an exit strategy when her stomach starts to turn.

“I get myself to a safe puke location,” she said.