Going in Circles: Thomson and Thompson Weren’t So Dumb

250px-Tintin_cover_-_Land_of_Black_Gold One of my favorite Tintin books is The Land of Black Gold. I am particularly fond of the part where Tintin’s hapless friends Thomson and Thompson ("Thompson with a ‘p’, like in ‘psychology’") drive in circles in the desert, repeatedly re-encountering their own tracks, thus convinced themselves they are on a freeway — until they run into their own gas tank, thus alerting them to their error.

Going in circles is a common problem. And not just in Tintin books, but among hikers and climbers, and politicians and central bankers too. In the absence of obvious signposts and while on unknown ground, our brains get confused and we have the bad habit of doubling back on ourselves — and then denying that we have.

There is a fascinating new paper in Current Biology on the subject, one that confirms that it’s far easier to go in circles than most of us think, with all sorts of unhappy consequences.

Walking Straight into Circles
Jan L. Souman, Ilja Frissen, Manish N. Sreenivasa, and Marc O. Ernst


Common belief has it that people who get lost in unfamiliar terrain often end up walking in circles. Although uncorroborated by empirical data, this belief has widely permeated popular culture. Here, we tested the ability of humans to walk on a straight course through unfamiliar terrain in two different environments: a large forest area and the Sahara desert. Walking trajectories of several hours were captured via global positioning system, showing that participants repeatedly walked in circles when they could not see the sun. Conversely, when the sun was visible, participants sometimes veered from a straight course but did not walk in circles. We tested various explanations for this walking behavior by assessing the ability of people to maintain a fixed course while blindfolded. Under these conditions, participants walked in often surprisingly small circles (diameter < 20 m), though rarely in a systematic direction. These results rule out a general explanation in terms of biomechanical asymmetries or other general biases. Instead, they suggest that veering from a straight course is the result of accumulating noise in the sensorimotor system, which, without an external directional reference to recalibrate the subjective straight ahead, may cause people to walk in circles.

More here.