Walking in Circles

On a scree slope in Slovenia, fog rapidly descended from the mountains, obscuring my sight on the valley below me. I worried that I would end up walking in circles, stepping from one loose stone to another until the evening covered the mountain in darkness. A feeling that was strangely reminiscent of doing data analysis.

Are we really doomed to walk in circles? Research from the German Max Planck Institute shows that humans indeed tend to walk in circles. – At least when your vision can’t show you the way.

An Experiment in the Desert

To find out whether people walk in circles, Jan Souman traveled to the desert. The desert is a place with almost no visual landmarks. The perfect condition for studying our internal sense of direction.

Jan Souman equipped participants with a GPS tracker such that he could trace their position. He pointed in a direction and asked the participant to walk straight in this direction for 50 minutes. The results showed that on cloudy days participants indeed walked in circles. When the sun was visible, they kept a relatively straight path.

Participant SK walked on a cloudy day. Participants KB and IK walked on sunny days. Image taken from Current Biology

Small errors in perception make us walk in circles

Why did people walk in circles? The direction in which participants veered varied from day to day. Therefore asymmetries in the body did not explain the circles.

In Current Biology, Jan Souman provides an elegant explanation. Perception isn’t always accurate: we often see or feel things in a slightly different place than where they really are. Our sense of direction also makes small errors. Normally this doesn’t matter because the world shows you that you made an error.

Shadows show us when heading direction veers.

It is clear that you made an error when you bump into an obstacle or leave the concrete of a road. The sun also helps. You may see that your direction towards the sun changes, or simply that the shape of your shadow changes. When we are in the desert on a cloudy day, there is nothing in the world to tell you that your sense of direction was off.

Okay, but doesn’t that just make us walk in the wrong direction rather than a circle? The key to walking in a circle is that each step follows from the previous step. Therefore errors in heading direction add up causing them to drift in a certain direction. The picture below illustrates that a drift in direction can cause you to walk in a circle.

When errors in direction add up (left image), we may end up walking in circles (right image)

The fact that errors add up isn’t always bad. Read how errors (sloppiness) can let you discover new solutions in my blog Sloppy Brain Sloppy Hands

I am off to walk some sunny mountains and already looking forward to the October motivation theme!



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