We introduce a new minimal model for self-propelled agents that attract, repel, and align to their neighbors through elastic interactions. This model has a simple mechanical realization and provides an approximate description of real-world systems ranging from active cell membranes to robotic or animal groups with predictive capabilities. The agents are connected to their neighbors by linear springs attached at a distance R in front of their centers of rotation. For small R, the elastic interactions mainly produce attraction-repulsion forces between agents; for large R, they mainly produce alignment. We show that the agents self-organize into collective motion through an order–disorder noise-induced transition that is discontinuous for small R and continuous for large R in finite-size systems. In large-scale systems, only the discontinuous transition will survive, as long-range order decays for intermediate noise values. This is consistent with previous results where collective motion is driven either by attraction–repulsion or by alignment forces. For large R values and different parameter settings, the system displays a novel transition to a state of quenched disorder. In this regime, lines of opposing forces are formed that separate domains with different orientations and are stabilized by noise, producing locally ordered yet globally disordered quenched states.

Schooling fish heavily rely on visual cues to interact with neighbors and avoid obstacles. The availability of sensory information is influenced by environmental conditions and changes in the physical environment that can alter the sensory environment of the fish, which in turn affects individual and group movements. In this study, we combine experiments and data driven modeling to investigate the impact of varying levels of light intensity on social interactions and collective behavior in rummy-nose tetra fish. The trajectories of single fish and groups of fish swimming in a tank under different lighting conditions were analyzed to quantify their movements and spatial distribution. Interaction functions between two individuals and the fish interaction with the tank wall were reconstructed and modeled for each light condition. Our results demonstrate that light intensity strongly modulates social interactions between fish and their reactions to obstacles, which then impact collective motion patterns that emerge at the group level.