This paper defines interactions among members achieving a common goal as coordinated group interaction, and offers a conceptual model based on a new perspective for understanding role-sharing. We assume familiar activities, such as team sports and outdoor cooking, and refer to findings from various research fields including cognitive science and sports science. To investigate the complex and dynamic behavior among three or more members, it is important to focus on top-down and bottom-up information processing; coordinated group interaction involves both types. Top-down processing refers to a feedforward mechanism that anticipates future situations and guides role-sharing to support efficient activities through a group mental model. It consists of structured internal knowledge-based representations that serve as a common ground and are strengthened by explicit instructions, within which information is shared and complemented among members. Bottom-up processing explains mutual adjustment through perception of the environment and others, enabling flexible reassignment of roles; this develops to update and expand the group mental model over time. However, few studies have proposed such an integrative group processing model based on both top-down and bottom-up mechanisms. We also introduce our field experiments in 3-on-3 basketball and barbecue cooking, and attempt to interpret the observed role-sharing and analysis results using the proposed model. Although further work is required, the novelty of these discussions lies in providing a crucial framework for understanding the process of coordinated group interaction in the real world.
