Looking for something to do outdoors with your extended family this Thanksgiving weekend?
Here’s an idea that combines science with exercise (well, a bit of exercise): Bet everybody that they can’t walk across an open field in a straight line while blindfolded.
It can’t be done. As 80 years of research has shown, every person who tries it ends up walking in circles instead.
In fact, blindfolded people also swim and drive (don’t try this with your family) in circles.
It’s a fascinating observation — and one NPR science reporter Robert Krulwich explored in an enlightening and amusing radio broadcast earlier this week. For his report, Krulwich talked with Jan Souman, a German researcher who published a study on the topic last year.
Souman and his colleagues had people walk blindfolded on both deserts and beaches for an hour. None could keep to a straight line, even though they thought they were doing so. He also had people walk unblindfolded in Germany’s Bienwald forest. On cloudy, low-visibility days, they, too, roamed in circles. But on sunny days, they were able to walk in a lengthy and somewhat straight line.
Said Krulwich: “Humans, apparently, slip into circles when we can’t see an external focal point, like a mountain top, a sun, a moon. Without a corrective, our insides take over and there’s something inside us that won’t stay straight.”
What is it that makes us turn? The answer has nothing to do with whether we’re right- or left-handed, or whether one of our legs is longer and/or stronger than the other, or whether one side of our brains contains excess neurotransmitters that encourage us to keep turning. Souman and his colleagues have tested — and ruled out — all those theories.
Souman believes the solution to the puzzle probably involves several causes, but what they are has yet to be determined.
“The real lesson here is that something as simple as walking straight can turn into such a mystery,” said Krulwich. “Which is why doing science like this is so much fun.”
Of course, Krulwich has a special knack for making science fun. His four-minute broadcast and illustrated video on this topic are no exception.
Try the experiment with your family this weekend. More fun than watching the Vikings — and you’ll be able to walk off at least a tiny bit of Thursday’s pumpkin pie.