August 21, 2009

Walking In Circles Not A Myth: Study

New European research using global positioning software finds that walking in circles when lost may not be simply a clich©.

The scientists presented the first empirical evidence that people do indeed walk in circles when they lack reliable cues to their direction.

Researchers in the Multi-sensory Perception and Action Group at the Max Planck Institute for Biological Cybernetics in Tbingen examined the walking trajectories of people who walked for several hours in the Sahara desert in Tunisia and in the Bienwald forest area in Germany.

The scientists used the global positioning system (GPS) to record these trajectories, and found that participants were only able to keep a straight path when the sun or moon was visible.  As soon as the sun disappeared behind some clouds, people began walking in circles without even realizing it.

"One explanation offered in the past for walking in circles is that most people have one leg longer or stronger than the other, which would produce a systematic bias in one direction. To test this explanation, we instructed people to walk straight while blindfolded, thus removing the effects of vision. Most of the participants in the study walked in circles, sometimes in extremely small ones (diameter less than 20 meters)," said Jan Seaman, who led the study along with Mar Ernst, group leader at the MPI for Biological Cybernetics.

However, these circles were rarely in a systematic direction, with the same person sometimes veering either to the left or the right.  Walking in circles is therefore not caused by differences in leg length or strength, but more likely the result of increasing uncertainty about which direction is straight ahead.

"Small random errors in the various sensory signals that provide information about walking direction add up over time, making what a person perceives to be straight ahead drift away from the true straight ahead direction," explained Seaman.

"The results from these experiments show that even though people may be convinced that they are walking in a straight line, their perception is not always reliable. Additional, more cognitive, strategies are necessary to really walk in a straight line. People need to use reliable cues for walking direction in their environment, for example a tower or mountain in the distance, or the position of the sun," said Ernst.

Seaman and Ernst now plan to study how people use these other sources of information to guide their walking direction. The scientists will use state-of-the-art Virtual Reality equipment, such as a revolutionary new omnidirectional treadmill.  Study participants will attempt to navigate their way through a virtual forest while walking in place on the treadmill and never leaving the laboratory. This will allow researchers better control over the information available to participants, making it possible to test specific theories, such as how people use the position of the sun to orient themselves.

The study was published today in the journal Current Biology.


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