The New York Times reports on a researcher who thinks the traditional explanation for motion sickness is all wet:
For decades now, [Thomas] Stoffregen, 56, director of the university’s Affordance Perception-Action Laboratory, has been amassing evidence in support of a surprising theory about the causes of motion sickness. The problem does not arise in the inner ear, he believes, but rather in a disturbance in the body’s system for maintaining posture. The idea, once largely ignored, is beginning to gain grudging recognition.
“Most theories say when you get motion sick, you lose your equilibrium,” said Robert Kennedy, a psychology professor at the University of Central Florida. “Stoffregen says because you lose your equilibrium, you get motion sick.”
That's kind of intriguing. But I can get severe motion sickness while sitting still in a seat on a perfectly calm airplane flight. It happens when I have a cold, or I'm recovering from a cold, and one ear clears but the other one doesn't as the cabin pressure is changing. It happens all the time to me, and the result is that the world starts spinning violently and I get dizzy and nauseous. This happens with no change in posture and no loss of equilibrium.
Maybe this is different from motion sickness, though. Seasickness does prompt some dizziness, but not quite the spinning world effect of one ear staying at a different pressure from the other.
On the other hand, sitting in an IMAX theater and watching a movie that simulates a roller coaster ride can induce motion sickness, even though you're sitting perfectly still. So what's up with that? Maybe you're not sitting quite as still as you think? Questions, questions.