Human crabs: An experiment to study the emergence of social norms and behavioral repertoires

¹ Graduate School of Engineering, The University of Tokyo, Tokyo, Japan
² Faculty of Information and Human Science, Kyoto Institute of Technology, Kyoto, Japan
³ Institute for Advanced Simulation, Forschungszentrum Jülich, Jülich, Germany

^* e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Published online: 12 September 2025

Abstract

Observational learning, colloquially known as “imitation,” is a mechanism in which people pick up a behavior seen in others. When a behavior spreads in a crowd through imitation, collective dynamics may change with consequences on crowd management and control. Imitation in the context of crowd has been studied for a long time, but supervised experiments with walking participants have been quite rare. In this work, we study whether and how naïve participants without instructions would imitate the behavior of others, even when the nature of behavior is far different from what is usually seen in daily scenarios, such as the behavior of participants trained to move like swarming animals. We observe that the initial conditions determine the emergence of a behavioral repertoire with different moving patterns in the two courses in which experiments were simultaneously performed. Our results show that, although imitation may actually occur, it takes places in the initial phases of the experiments with the final outcome mostly depending on initial conditions. Further, once a behavioral repertoire is formed it will not change throughout the length of the experiment despite our attempts to modify it.