Transient Milling Dynamics in Collective Motion with Visual Occlusions

Palina Bartashevich, Lars Knopf, Pawel Romanczuk

Abstract: The coordinated circular motion of individuals within a group, known as milling, is a widely observed collective motion pattern across biological and artificial systems. However, existing models focused on achieving stable, albeit unnatural, patterns, while overlooking the embodiment aspect of real-world agents. Here, we employ a spatially explicit agent-based model with visual occlusions and a collision avoidance mechanism to address this gap and investigate the emergence of temporary milling states over time. We show that short yet frequent milling dynamics are prevalent in a distinct parameter region, characterised by a qualitative shift in group behaviour between dynamical regimes, suggesting adaptability. We also show that such milling states require a minimal field of vision that not only promotes their occurrence but also matches the typical field of view observed in biological systems.