People really do walk in circles when they get lost.
Straying from the straight path. I'm Bob Hirshon and this is Science Update.
People really do walk in circles when they get lost. This according to Jan Souman of the Max Planck Institute for Biological Cybernetics in Germany. He and his colleagues dropped people in an unfamiliar forest or desert, and tracked them via GPS. Souman says that if the sun or moon was out, the volunteers were able to walk straight ahead. But when it was cloudy, they walked in circles.
We didn't expect to find that at the beginning. We thought that people would do something random, but not really walk in circles.
What's more, he says the circles were surprisingly small: just a few hundred yards in diameter. Further tests showed that people don't automatically default to one direction or another. Rather, Souman suspects that without a fixed reference point like the sun, misleading sensory cues can make us veer slightly left or right without realizing it. I'm Bob Hirshon for AAAS, the Science Society.
Making Sense of the Research
Many ideas become embedded in our thinking without ever having been proven true. One of these is the idea that when people get lost, they end up wandering around in circles. In fact, we use the expression "going around in circles" to mean "lost" or "confused," even when we're not talking about being physically lost. For example, a detective on a TV show might say it when she's having trouble cracking a case. Souman's team decided to put the underlying assumption to the test, and was surprised how true it was.
Their experiment, though simple, would have been difficult to pull off before the advent of the global positioning system, or GPS, which makes it possible to track anyone or anything from any distance. They simply dropped a volunteer in the middle of an unfamiliar environment, and told him to try and walk a straight line. Now, it couldn't be just any environment: for example, if you dropped someone off in the middle of New York City, even if he'd never been there before, he could walk a straight line simply by following the sidewalk. In order to observe people's sense of direction in its purest form, the researchers had to choose environments that looked pretty much the same no matter where you went, so that their subjects couldn't get their bearings from external cues. That's why they chose either a forest or a desert.
However, there was one external cue that the researchers couldn't control: the sun (or, at night, the moon). As you heard, their subjects were fairly good at walking a straight line with nothing but the sun or moon to guide them. But on cloudy days, when the sun or moon was hidden, the volunteers really did walk in circles. In fact, they walked in fairly small circles, only a few hundred yards across. Imagine if you really were lost in the Sahara Desert, and couldn't get further than a quarter mile from where you started!
To find out why people walked in circles, they did further experiments indoors, with blindfolded volunteers. One hypothesis was that each person tends to drift slightly left or slightly right as she walks, depending on her exact body structure. Walking slightly to one side or the other, without correcting course, would result in making a circle. However, the researchers found that individual people didn't consistently drift left or right. For example, in one trial, a blindfolded volunteer might walk in a circle by drifting left, and in another trial the same person would walk in a circle by drifting right. That suggests that our body shape itself doesn't create the walking in circles effect.
It's not clear what does, but Soumans has another hypothesis: without meaningful clues for navigation, our brains may latch onto subtle, misleading cues in our environment—perhaps the slope of the ground, or the direction of the wind—in order to pick a direction. The overall effect of this sensory "noise" biases us to walk at one angle or another, but the exact angle differs depending on the circumstance. It would take more extensive brain research to figure out if this is really the case.
Now try and answer these questions:
- What was the purpose of this experiment?
- Why was the experiment designed the way it was? Why did they choose the forest or the desert locations?
- Why do the researchers think that our body structure isn't what makes us walk in circles?
- Can you think of other situations in which we rely on environmental cues to calibrate our sense of space, time, and motion? What happens when those cues are absent?
In the National Geographic lesson plan Animals vs. People: Who's the Better Navigator?, students read about animal navigation and then compare animal to human navigational capabilities. They then create travel brochures for an Outward Bound-style company, providing customers with tips on how to find their way if they get lost and can't rely on their map and compass.
The National Geographic News article Racing in Packs offers information on another aspect of human movement: how "bunching" in triathlons or cycling races gives some racers an advantage that masks their individual ability.