Changes in coordinative structure through human-environmental interaction and its role in estimation of dynamics

Humans are able to acquire information on dynamics that cannot be directly obtained through observation of kinematics. Since the coordinative structure of the human behavior is self-organizing in interactions with the environment, a change in the environment induces a change in the coordination structure. It is posited that humans identify dynamic interactions between the body of the actor and the external environment through the interpolation of coordinated structures for observed behaviors. Coordinative structures consist of invariant part and covariant part. Invariant part is a set of motion change points which are found even if the environment or dynamic interaction has changed. Covariant part is a set of motion change points caused by the environmental changes. In this paper, we examine more closely the changes in coordinative structure induced by changes in dynamic interactions with the environment, and describe a method to extract invariant and covariant part of coordinative structures. Moreover The importance of the change in the coordinated structure in recognition of the dynamic interaction by observers is also described. The results of dynamics recognition experiments revealed that information necessary for the estimation of relative weight is contained in the covariant part of the coordinated structures but not in their invariant regions, and furthermore that timing is also an essential for estimation.