Have you ever noticed that you naturally drift in a certain direction while walking through a crowded mall or festival? According to an international study led by the University of Navarra and the Universidad Carlos III de Madrid (UC3M), humans have a slight but consistent tendency to move toward the left. This discovery could impact everything from airport design to stadium safety. The research, conducted with Waseda University, the University of Tokyo, and Shanghai University, was published in Nature Communications.
Why We All Lean Left
For years, researchers believed that crowds organized themselves through simple interactions: people avoid bumping into each other, follow local customs, and adapt to surroundings. However, the new study uncovered a missing piece of the puzzle. Iñaki Echeverría, a researcher in Physics and Applied Mathematics at the University of Navarra and first author of the paper, explained: "For decades, we thought collective patterns arose solely from pedestrian interaction. Our work shows that a significant part of these patterns is inherent to the individual."
When groups walk together, whether in enclosed rooms or open spaces, they naturally move in a counterclockwise pattern. While this preference is small at an individual level, it amplifies with hundreds or thousands of people, creating observable large-scale patterns. Echeverría noted: "Not all group members exhibit this preference, but a large majority do tend to move counterclockwise. This inclination dictates the group's direction and gives rise to visible collective patterns."
It's Not Culture, Environment, or Habit
The researchers discovered that this counterclockwise tendency persists beyond cultural norms and environmental factors. To test traditional explanations, they conducted an extensive experimental campaign over several years in Spain and Japan. This allowed them to analyze whether the phenomenon depended on how pedestrians avoid collisions, given that people in both countries typically move and dodge on opposite sides. The study included groups of adults walking in controlled spaces, schoolchildren in open yards, preschool children, and individuals completing routes alone.
The team also ruled out social norms as a cause. They surveyed participants about social expectations. Anxo Sánchez, from the Mathematics Department at UC3M, stated: "The results were clear: there was no notable social norm. If anything, data suggests the norm would be to walk clockwise—in complete contradiction with the experiment—so it cannot explain the observations."
The tendency persisted even when other factors were removed. It appeared in young children who hadn't learned walking rules, in open spaces with no barriers, and in countries with different traffic patterns. Iker Zuriguel, Professor of Applied Physics at the University of Navarra and a main author, noted: "We wanted to find out if the phenomenon depended on cultural norms, interaction with the environment, or pedestrian avoidance strategies. The results indicate none of these factors fully explains what we observed."
Designing Better Public Spaces
The findings provide new insights into human behavior that can be applied to urban mobility and crowd management. This information is crucial in high-density environments like airports, train stations, shopping centers, and sports venues, where models are used to optimize routes and reduce congestion. Zuriguel added: "Better understanding the factors that influence movement allows for more precise models of how people circulate in shared spaces. This could help design more efficient infrastructure and environments that adapt to our daily movements."
Echeverría concluded: "The results suggest individual predispositions play a relevant role in collective movements. The study opens new questions about the biological origin of these tendencies, as similar phenomena are observed in other animal species, from fish schools to insect colonies."
