Centuries of sailors weren't wrong: Looking at the horizon stabilizes posture

Jan 26, 2011

Everybody who has been aboard a ship has heard the advice: if you feel unsteady, look at the horizon. For a study published in Psychological Science, a journal of the Association for Psychological Science, researchers measured how much people sway on land and at sea and found there's truth in that advice; people aboard a ship are steadier if they fix their eyes on the horizon.

Thomas A. Stoffregen of the University of Minnesota has been studying "body sway" for decades—how much people rock back and forth in different situations, and what this has to do with motion sickness. In just a normal situation, standing still, people move back and forth by about four centimeters every 12 to 15 seconds. Stoffregen and his coauthors, Anthony M. Mayo and Michael G. Wade, wanted to know how this changes when you're standing on a ship.

To study at sea, Stoffregen made contact with the U.S. consortium that runs scientific research ships. "I'm really an oddball for these folks, because they're studying oceanography, like hydrothermal vents. Here's this behavioral scientist, calling them up," he says. He boards a ship when it is travelling between different projects—for example, in this study, he rode on the research vessel Atlantis as it went between two points in the Gulf or California. "It had nothing to do with the fact that I like cruising near the tropics," he jokes. Since the ships are between scientific expeditions, he can sleep in one of the empty bunks normally reserved for ocean scientists, and crew members volunteer to take part in his study.

The study compared the same people standing on dry land—a dock in Guaymas, Mexico—and aboard the ship. In each experiment, the crew member stood comfortably on a force plate and focused on a target—either something about 16 inches in front of them, or a far-off point; a distant mountain when standing on land or the horizon when standing on the ship. On land, people were steadier when they looked at the close-up target and swayed more when they looked far away. On the ship, however, they were steadier when they looked at the horizon.

This is actually counterintuitive, Stoffregen says. When you're on a ship, you need to adjust to the ship's movement, or you'll fall over. So why would it help to look at the horizon and orient yourself to the Earth? He thinks it may help stabilize your body by helping you differentiate between sources of movement—the natural movement coming from your body and the movement caused by the ship.

Stoffregen thinks this motion of bodies may predict motion sickness. "It's the people who become wobbly who subsequently become motion sick," he says. He had originally hoped to study seasickness directly, but so far his subjects have all been seasoned crew members who are used to the ship's movement and don't get sick; his dream is to do his experiments aboard a ship full of undergraduate oceanography majors going to sea for the first time. "I'd give my right arm to get on one of those."

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User comments : 3

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Hesca419
1 / 5 (1) Jan 26, 2011
Probably asking for trouble here, but...

This seems very reminiscent of the "unbendable arm," a chi-focusing technique used in Aikido and other Asian martial arts. By focusing one's attention on a distant object one can create a relaxed yet rigid limb with more strength than can be attained merely tensing the muscles. Yoga also uses a similar method of stretching various parts of the body, particularly the head and back, towards impossibly distant targets to improve muscle tone, posture, and "energy". Particularly considering that this article is merely observation and has no mechanism to explain its action, I respectfully suggest this Stoffregen fellow study an eastern martial art or, at least, artist.
ryggesogn2
3 / 5 (1) Jan 26, 2011
Just because 'science' can't explain why, doesn't mean it is not true.
There have been more sailors than scientists throughout history.
gwrede
not rated yet Jan 27, 2011
This article is written like something in a womens' magazine. Also, Stoffregen's ruminations at the end of the article are on a level of an ignorant city-dweller.

There is not a single sentence here that would earn the right to appear on this website.
Thomas A. Stoffregen of the University of Minnesota has been studying "body sway" for decades—how much people rock back and forth in different situations, and what this has to do with motion sickness.
He had originally hoped to study seasickness directly, but so far his subjects have all been seasoned crew members who are used to the ship's movement and don't get sick;
No wonder this guy still is at square one.