In the movies, when hikers get lost in the woods, you know that they are well and truly lost by the third time or so that they pass by that big rock or funny-looking tree. And you just know that that would never happen to you. If you set out on a straight line, you would never double back without intending to do so.
Well, you'd be wrong.
People do walk in circular paths when they are lost, according to a study published online today by Current Biology. Scientists from the Max Planck Institute for Biological Cybernetics in Germany started their experimentations by first letting a few volunteers loose in a large, flat German forest and tracking them by GPS. Those who wandered on a sunny day kept to a nearly straight path while participants who trekked on a cloudy day walked in circles. Three of the cloudy day walkers even repeatedly crossed their own paths and without ever realizing what they were doing.
The scientists repeated their experiment in the Sahara Desert in Tunisia. Two people who walked during the day veered a bit off course (not too shocking when every direction looks similar) but the participant who walked at night managed to keep to a straight line only until the moon became covered by clouds.
In another experiment, the scientists blindfolded their subjects, who were then told to walk a straight line. But without anything to guide their paths, they walked in circles.
Throughout the experiments, though, the participants did not favor any one direction. Sometimes they would veer left, at other times, right. This rules out the idea that we walk in circles because we favor one leg over the other due to leg length or strength. Instead, the scientists say, without something like the sun or a mountain around to help us calibrate "straight," the "noise" in our sensorimotor system sends us off track. However, the scientists note:
In emergency situations, where one's life depends on the ability to navigate through unfamiliar terrain and reach safety, emotional state (panic) and social factors (group dynamics) may cause these cues and more cognitive navigation strategies to be disregarded, making people walk in circles even in the presence of reliable directional cues.
In the researchers' next experiment, they will have participants walk through a virtual reality environment on a treadmill that lets a person walk in any direction (video below) to better determine the factors that help a person to walk straight or sets them into circles.