By Dr. Brian McDonough, Medical Editor

PHILADELPHIA (CBS) - Have you ever seen one of those movies where a person who is lost leaves something behind to see if they pass that way again? There is a reason why this is important.

Without a guide, people really do walk in circles. A German study found that without absolute references like the sun or the moon, people attempting to walk in a straight line in unfamiliar territory will instead walk in circles.

Researchers had people attempt to walk straight in one direction for several hours through a flat forest or the sahara desert. Some walkers had the sun or moon to guide them, while others walked when the clouds obscured their reference point.

When the sun or moon was visible, subjects walked a perfectly straight line, but whenever this reference was absent, subjects invariably walked in circles, often crossing over their own paths several times each.