Aug. 20, 2009 -- If you've ever been lost and got the feeling you were just retracing your steps, chances are you're right.
According to a new study, humans really do walk in circles when they're set loose in the wilderness -- at least on cloudy days. Worse, we don't even believe we're doing it when we're shown proof.
A group of scientists at the Max Planck Institute for Biological Cybernetics in Tubingen, Germany, decided to test the long anecdotal warning that hikers could circle their tracks without a map. So the researchers outfitted nine people with a Global Positioning System tracking device, and dropped them off either in a flat forest in Germany or the Sahara desert in southern Tunisia and told them simply to walk for several hours in a straight line in one direction.
Two people walking in the desert during daylight veered from their course, but didn't walk in circles. A third person walking in the desert, this time at night, walked in a straight line until the moon went behind some clouds.
"Once the moon disappeared behind the clouds, all of a sudden he turned 90 degrees, and turned 90 degrees again," said Jan Souman, the lead author of the study published today in the journal Current Biology. "In a desert you really can walk in a straight line, if you have the sun to guide you."
Souman and his colleagues decided to include the second forest experiment to see how well people could keep a straight course when they were forced to maneuver around objects. Not surprisingly, people in the forest fared even worse and again, cloud coverage made a difference.
The four volunteers who walked on a cloudy day in the forest repeatedly went in circles, sometimes every 10 minutes.
"They didn't really believe when we showed them afterwards," said Souman. "I think that's certainly a point to take away, people may feel very confident about the direction where they're going but it's not certain."
Tod Schimelpfenig, the curriculum director for the Wilderness Medicine Institute of the National Outdoor Leadership School (NOLS), said he was glad to see some science behind what he and many of his fellow wilderness experts see often in search and rescue missions.
It May Be Human Nature to Go in Circles When You're Lost
"I think we've always thought it was a tendency we all have," said Schimelpfenig, who works in search and rescue in Wyoming and is also a former NOLS instructor.
"If there's terrain, then it gets complicated -- then people get funneled by the terrain," said Schimelpfenig. "If you were in the middle of a big flat, featureless place, that's when we tend to see this."
Souman said his study was the first to test the tendency to walk in circles outdoors; however other researchers have found people tend to walk in circles if they're blindfolded.
"If you look at the shapes of the trajectories outside, the circles had a diameter of about 200 to 300 meters," Souman said. "Blindfolded the circles were 15 to 60 meters in diameter. Those circles could be really, really small."
But Souman's work is intended to do more than make us feel inept as a species. Researchers have long been arguing over why we turn in circles, and Souman said the new study may rule out one of some of the leading hypothesis.
For example, since the people in the experiment tended to turn at random in any direction, Souman says it counters the theory that we walk in circles without visual cues because we have one leg that is stronger or longer than the other.
Instead, Souman hypothesized that we walk in circles because our brains accumulate faulty signals about the body's position in space.
"Your vestibular system tells you about your balance," Souman said. As we walk our muscles, bones, joints and inner ear all send signals to the brain to help us orient ourselves.
"All those signals have small errors, because it's a biological system, and those random errors will accumulate and sometimes they accumulate in one direction," Souman said.
When we have visual cues like landmarks or the sun, Souman said the brain can recalibrate every so often and adjust for these imperfect signals.
But what Souman's research hasn't done is to help people keep going straight in the woods, something that experienced survival instructors say can be a difficult task, even with a map or compass.
GPS Is No Replacement for Navigation Skills in the Wilderness
"In short-term travel even, if the vegetation is very dense you have to pick a tree even 30 feet in front of you to guide, then you pick another," Schimelpfenig said.
The standard advice for a person lost in the wilderness is to stay put, but Schimelpfenig said people often don't listen to that advice.
"I think the tendency is to move, we all want to find ourselves. But that makes it much more difficult for search teams to find a moving target," he said. "If you are lost and there's any chance that somebody's coming to look for you, I think the best thing is to stay put and be visible."
Schimelpfenig and other experts say experience reading maps is the best way to keep from getting lost, and warn people who think they can rely on GPS systems alone.
Billy Roos, associate director of safety at Outward Bound said he starts his students out on maps alone first, and then trains his students to use maps with compasses and rarely turns to GPS devices.
"It's tough in my opinion to jump right into using a GPS if you don't have a foundation in the more fundamental aspects of navigation," Roos said.
Roos said it can take a while before people are "wired" and can easily translate the symbols of the map to their surroundings, and envision their real surroundings on the map. Only then, and only after learning to use a compass, would he recommend navigating with a GPS.
Schimelpfenig said he's even had to come to the rescue of people using their GPS device in their cars.
"GPS will get you from point A to point B but it won't tell you in between there's a river bottom, a muddy dirt road, or a hole," he said, and that's one reason why he was pleased to see some science on how we walk in circles.
"To me it's a reminder that we don't have an innate sense of direction," Schimelpfenig said. "When you go out in the wilderness you have to have navigation tools."