We all go round in circles

Posted by Emma Woollacott

Tubingen, Germany - People really do walk in circles when they're lost, and it's not because their legs are different lengths.


That's the conclusion of scientists in the Multisensory Perception and Action Group at the Max Planck Institute for Biological Cybernetics.


They dumped people in either in the Sahara desert or the Bienwald forest in Germany and set them walking "for several hours", following them via GPS and probably cackling with glee.


As long as the sun or moon was visible, the participants were able to keep a straight path. But a cloudy day foxed them completely, and they started to walk in circles without even noticing 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," said one of the authors, Jan Souman. "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 metres)."


The leg-length theory was exploded by the fact that the circles were rarely in a systematic direction, with the same person sometimes turning left, sometimes right.


"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," according to Souman.


The guys haven't finished yet. In future research, they plan to examine the even more bewildering question of how people use the sun and other cues such as tall buildings to guide their walking direction.


This sounds rather less unpleasant for their volunteers, as they get to use state-of-the-art virtual reality kit, including a cool new omnidirectional treadmill.


The study is published today in Current Biology.