Experimental study on crowd following behavior under the effect of a leader

It is widely accepted that effective leadership can improve evacuation efficiency, so how to guide the crowd effectively deserves great attention. However, little research has been done on the effect of an individual on crowd following behaviors in two-dimensional scenarios, especially the agreement between the followers and the leader. In this study, several controlled experiments were conducted to explore the effect of an individual (the leader) on the crowd movement, considering different group sizes and the leader's speeds. A new method was proposed to evaluate the leadership effect based on the agreement between the followers' and the leader's motion. Different weight parameters were defined to reflect different states including speed matching, angular speed adjustment, and the states of ineffective leadership. The results showed that the leadership effect was weakened as the leader's speed or the group size increases, and the leader's speed had a greater impact on the leadership effect than the group size. The formation coordination of the crowd showed a little difference at different leader's speeds but a large difference under different group sizes. These findings can provide empirical data about the effect of a leader on crowd following behavior, which might be useful for the improvement of the leader–follower model and provide new insights into the leadership of the crowd.