Towards the end of Lord of the Rings: The Return of the King, Frodo and Sam hike through Mordor, heading in the direction of Mount Doom to destroy the Ring. Despite their best efforts, however, they find themselves continually returning to the same hill. Perhaps that movie reference was a bit obscure, but it’s a familiar situation in movies, novels and even personal experience: in an attempt to follow a straight course, we somehow end up right back where we started. How is it that we always manage to end up unconsciously walking in circles?



With a study done by Jan Souman of the Max Planck Institute for Biological Cybernetics in Germany and published last year in Current Biology, our documented tendency to aimless wandering has been scientifically confirmed. Without a point of reference such as the sun, a compass, or the tip of a mountain to follow, people trying to follow a straight course will indeed end up in the same place they started from. Something as simple as walking in a straight line actually involves the work of multiple senses, along with our motor actions and cognition.

In a series of experiments, the researchers instructed participants to walk as straight as they could through a forest (where one tree can begin to look like another) on both a cloudy and a sunny day. They noted that when the sun (an easily distinguishable reference point) was out, participants were able to follow almost a perfectly straight course. However, when the weather was cloudy, all of them went in circles! In the next part of the experiment, the researchers instructed people to walk in a straight line in the Sahara desert; though some participants strayed from a completely straight line, they did not walk in a circle (they had the sun as a reference). However, when the same experiment was conducted at night when the moon disappeared behind the clouds, the participant unknowingly veered into a circle and headed towards the starting point. These experiments proved that with a lack of an absolute reference (a building, mountain, sun, or moon), people would tend to walk in circles.

But even if this is true, we’re still left with the question of why. Souman tested the possibility of left or right-handedness, different levels of dopamine on the different sides of our brain, and even bigger muscles or stronger appendages on one side. However, no single explanation was satisfactory in describing this phenomenon. Instead, Souman suggests that walking in a straight line is an extremely complex task involving the brain, sense of sight and proprioception (our sense of where parts of the body are relative to each other in space), spatial awareness and sense of balance. When any of those elements are in any way disrupted, people tend to drift randomly.

This study shows us how crucial our different senses are for navigation. Collectively, they are able to provide us with the amazing ability to find our way through even the most complicated routes. However, the handicap of even one of these senses may just leave us walking in circles.

For more information, take a look at these articles:

http://www.npr.org/blogs/krulwich/2010/11/03/131050832/a-mystery-why-can-t-we-walk-straight

http://www.usnews.com/science/articles/2009/08/21/how-to-walk-in-circles-without-really-trying.html

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