Complexity matching: adaptive strong anticipation enhances motor coordination.

Coordination of movement between pairs of individuals or in groups is a routine aspect of social behavior. Successful coordination is predicated on adaptation of movement timing by the individuals forming the group. The purpose of the present study is to examine whether motor coordination between dyads reflects weak or strong anticipation. Weak anticipation is reflected in local adjustments to motor behavior to account for prediction errors. Strong anticipation reflects the knowledge of the long-range statistics of the environment (e.g., variability in movement dynamics) in order to predict and coordinate with future events. Previous studies of rhythmic behavior have demonstrated that movement dynamics exhibit long-range correlations and complexity, suggesting that strong anticipation could play a role in coordination. We investigated two finger tapping coordination tasks, synchronization and syncopation, with different types of on-screen responses between two individuals. The results indicate that the timing of motor action exhibits long-range correlations reflected in measures of complexity (Hurst exponents). When two individuals coordinate their motor behavior, they can exhibit adaptive strong anticipation by complexity matching, more prominently in syncopated than in synchronized motor coordination. During syncopation, individuals strongly synchronize their tapping intervals when provided mutual on-screen responses. Matching of tapping intervals in syncopation is not fully explained by prediction error correction, but instead mutual adaptation and the emergence of coordinated dynamics. In synchronization, coordination always reflects a leader and follower, even in mutual response conditions, suggesting a dominant role for weak anticipation. We probed the brain network dynamics underlying strong and weak anticipation by functional connectivity analysis of simultaneous EEG recordings. Graph-theoretic analysis revealed distinct patterns of hubs formed in occipital/parietal regions in syncopation and over the frontal cortex in synchronization. Motor coordination between individuals is supported by distinct brain networks during strong and weak anticipation, with more precise coordination facilitated by strong anticipation.