Aug. 20, 2009 -- When you're lost and trying to walk back to familiar territory, don't count on your sense of direction to steer you straight.
A new study shows that you're likely to go walking in circles, rather than in a straight line, if you don't have any landmarks to guide you.
"The stories about people who end up walking in circles when lost are actually true," researcher Jan Souman, PhD, of Germany's Max Planck Institute for Biological Cybernetics, says in a news release.
Souman's team asked people to walk a straight course for several hours through landscapes they didn't know -- a German forest and part of the Sahara desert in southern Tunisia.
Participants wore GPS devices, which showed that they walked a fairly straight path when the sun or moon was out. But when cloudy skies left them without those beacons, they started walking in circles.
Participants didn't look up at the skies very often; shadows may have been the cues they needed, the researchers note.
Souman and colleagues also blindfolded participants and watched them walk on an airstrip and runway that weren't in use.
At first, people did well walking in one direction. But the longer they walked, the more they veered off course. And if people are stressed and panicky, which wasn't the case in these studies, their emotions may make it harder for them to pick up on landmarks, the researchers write in Current Biology.
"Ironically, in an age of ubiquitous navigation systems in airplanes, cars, and even mobile phones, we are only beginning to understand how humans navigate through their environment, exploring uncharted terrain," write the researchers. "Our results here show that the seemingly simple act of walking in a straight line actually involves a complex interplay of various sensory modalities, the motor system, and cognition."