Buzz
It's a classic trope in films: The protagonists are stranded in the wilderness, trying their hardest to escape the forest or find their way back to camp or civilization, only to become disoriented and find themselves returning to the spot where they started.
When a science TV show approached Jan Souman, a research scientist at the Max Planck Institute for Biological Cybernetics, with a viewer’s inquiry about the behavior, Souman was initially skeptical that people truly looped back by accident. His assumption was that lost individuals would veer left or right at random, but not necessarily retrace their steps.
To investigate, Souman and his team assembled nine volunteers, sending six to a forest in Germany and the remaining three to the Tunisian desert. Each participant was instructed to walk in a straight line for several hours while wearing GPS devices to allow the researchers to track their paths and analyze their movements.
Course Correction
Souman discovered that every participant deviated from their intended path, with more than half unknowingly retracing their steps. An intriguing detail emerged: the circling occurred only among four of the forest walkers who traveled in overcast weather and one desert walker who ventured out on a moonless night. Those who had access to the sun or moon managed straighter courses, and when they did lose their way, they moved as Souman had anticipated, veering left or right but still heading in the same general direction, never crossing their original path.
In a follow-up experiment, 15 volunteers attempted to walk straight for an hour while blindfolded. Without sight, the participants circled back sooner, more frequently, and in tighter arcs, sometimes forming circles as large as a basketball court.
The two experiments challenged an older theory suggesting that such disorientation could be attributed to biomechanical differences—like slight variations in leg length or strength—that caused a directional bias. According to this idea, a person would consistently drift in one direction, especially when blindfolded and without visual cues to counter the bias. However, only three participants consistently veered in one direction, while the rest exhibited erratic patterns, as if a child had doodled on paper. Souman and his team propose that walking in circles is not due to a physical bias, but rather a growing uncertainty about the direction of straight ahead.
Visual Clues
For the participants in the initial experiment, visual cues were crucial. Those who had access to some form of external reference—like the sun, the moon, or a distant hill—could use these to realign their sense of direction and keep moving in a relatively straight line. (Interestingly, Souman points out that the volunteers walked for hours during which the sun shifted by about 50 to 60 degrees. Despite this, they managed to adjust their course, often without conscious effort.)
The participants who walked in cloudy or dark conditions, or while blindfolded, lacked this advantage and ended up walking in circles. With no reference point to guide them, they had to depend on other cues, such as sounds and signals from the vestibular system, which helps with movement, balance, and spatial awareness. Souman and his team suggest that small, random errors in processing these cues accumulate over time, particularly when sensory input is limited. Eventually, the internal sense of direction falters, and 'random changes in the subjective sense of straight ahead' cause individuals to veer off course and end up right where they began.
