Group formation and cohesion of active particles with visual perception-dependent motility

Clemens Bechinger
University of Konstanz, Germany

Abstract:
Group formation is frequently observed in living systems. It typically results from a delicate balance of repulsive, aligning, and attractive mutual interactions. Here, we show that a motility change of individuals in response to their visual perception of the group is sufficient to induce formation and cohesion of stable groups. Experimentally, this is demonstrated using active particles whose motility is controlled by an external feedback-loop. We demonstrate that when individuals have a relatively narrow field of view, they gather into strongly cohesive groups while remaining highly motile. For larger field of views, cohesion can only be achieved by lowering the response threshold. Our results are supported by simulations with point-like particles, which confirms that active re orientations are not necessary to ensure cohesion, as often assumed. We expect this group formation mechanism to be relevant not only for the self-organization of living systems, but also for the design of autonomous self-propelling systems.