Effective leadership and decision-making in animal groups on the move Lain D. Couzin, Jens Krause, Nigel R. Franks, and Simon A. Levin investigate how information is transferred and decisions are made in animal groups moving together. They show that information can be shared without explicit signals, even when group members do not know who has information. Larger groups require fewer informed individuals to guide the group effectively, and only a small proportion is needed for high accuracy. Groups can reach consensus even when informed individuals do not know if they are in the majority, how their information compares, or if others have information. The study uses a model to simulate how individuals modify their movement based on local neighbors. Groups consist of N individuals, each with position, direction, and speed. They maintain personal space and avoid collisions. Informed individuals influence group direction based on a weighting term, ω, which balances their preferred direction with social interactions. As ω increases, individuals are more influenced by their preferred direction. The accuracy of group motion is measured by the normalized angular deviation around the preferred direction. For a given group size, accuracy increases with the proportion of informed individuals. Larger groups require fewer informed individuals for high accuracy. However, increasing ω has trade-offs between accuracy and group cohesion. Informed individuals may differ in preferred direction due to experience or motivation. Groups must make collective decisions, such as moving to a resource. The study shows that groups can select the majority direction even with small numbers of informed individuals. A feedback mechanism on ω allows groups to reach consensus when preferences differ. The model shows that efficient information transfer and decision-making can occur without explicit signals or complex mechanisms. Leadership emerges from information differences, not dominance. The mechanism requires limited cognitive ability and allows spontaneous responses to informed individuals. This has implications for understanding group foraging, social learning, migration, and navigation, and may inform design protocols for information transfer in robotic groups.Effective leadership and decision-making in animal groups on the move Lain D. Couzin, Jens Krause, Nigel R. Franks, and Simon A. Levin investigate how information is transferred and decisions are made in animal groups moving together. They show that information can be shared without explicit signals, even when group members do not know who has information. Larger groups require fewer informed individuals to guide the group effectively, and only a small proportion is needed for high accuracy. Groups can reach consensus even when informed individuals do not know if they are in the majority, how their information compares, or if others have information. The study uses a model to simulate how individuals modify their movement based on local neighbors. Groups consist of N individuals, each with position, direction, and speed. They maintain personal space and avoid collisions. Informed individuals influence group direction based on a weighting term, ω, which balances their preferred direction with social interactions. As ω increases, individuals are more influenced by their preferred direction. The accuracy of group motion is measured by the normalized angular deviation around the preferred direction. For a given group size, accuracy increases with the proportion of informed individuals. Larger groups require fewer informed individuals for high accuracy. However, increasing ω has trade-offs between accuracy and group cohesion. Informed individuals may differ in preferred direction due to experience or motivation. Groups must make collective decisions, such as moving to a resource. The study shows that groups can select the majority direction even with small numbers of informed individuals. A feedback mechanism on ω allows groups to reach consensus when preferences differ. The model shows that efficient information transfer and decision-making can occur without explicit signals or complex mechanisms. Leadership emerges from information differences, not dominance. The mechanism requires limited cognitive ability and allows spontaneous responses to informed individuals. This has implications for understanding group foraging, social learning, migration, and navigation, and may inform design protocols for information transfer in robotic groups.