Everyday human actions often occur in a social context. Past psychological research has found that the motor behavior of socially situated individuals tends to be coordinated. Motivated by the seminal work of Schmidt, Carello and Turvey, (1990) our research performed over the last 25 years has sought to understand how the mutuality, accommodation, and synchrony found in everyday interactional coordination can be understood using a dynamical theory of behavioral order, namely coordination dynamics. Using laboratory interpersonal tasks, we have demonstrated that when two people are asked to rhythmically coordinate their limbs they show behavioral phenomena identical to those found in bimanual interlimb coordination, which has been mathematically modeled as a dynamical coupled oscillator process (e.g., Richardson et al., 2007; Schmidt et al., 1994; 1997). Research has demonstrated that these same dynamical organizing principles can coordinate the rhythmic movements of two people unintentionally (e.g., Richardson et al., 2005; Schmidt & O’Brien, 1997) and that the weaker, intermittent coordination that ensues is affected by both perceptual (e.g., attentional focus and information pickup activity of the visual system; e.g., Schmidt et al., 2007) and dynamical constraints (e.g., intrapersonal rhythmic synergies and period basin of entrainment; e.g., Lopresity-Goodman et al., 2008). Other research has investigated how traditional social and personality properties of a dyad (rapport, social competence) relate to dynamical properties of a dyad’s coordinated movements and how the stability of coordinated movements mirrors the stability of mental connectedness experienced in social interactions (e.g., Miles et al., 2011; Schmidt et al., 1994).
Lopresti-Goodman, S., Richardson, M. J., *Silva, P. L., & Schmidt, R. C. (2008). Period Basin of Entrainment for Unintentional Visual Coordination. Journal of Motor Behavior. 40, 3-10.
Miles, L. K., Lumsden, J., Richardson, M. J., & Macrae, N. C. (2011). Do Birds of a Feather Move Together? Group Membership and Behavioral Synchrony. Experimental Brain Research, 211, 495-503.
Richardson, M. J., Garcia, A., Frank, T. D., Gergor, M., & Marsh, K. L., (2012). Measuring Group Synchrony: A Cluster-Phase Method for Analyzing Multivariate Movement Time-Series. Frontiers in Physiology. 3, 405.
Richardson, M. J., Marsh, K. L., & Schmidt, R. C. (2005). Effects of visual and verbal information on unintentional interpersonal coordination. Journal of Experimental Psychology: Human Perception and Performance, 31, 62-79.
Richardson, M. J., Marsh, K. L., Isenhower, R., Goodman, J., & Schmidt, R. C. (2007). Rocking Together: Dynamics of Intentional and Unintentional Interpersonal Coordination. Human Movement Science.26, 867-891.
Romero, V., Coey, C., Schmidt, R. C., & Richardson, M. J. (2012). Movement Coordination or Movement Interference: Visual Tracking and Spontaneous Coordination Modulate Rhythmic Movement Interference. PLoS ONE 7(9): e44761.
Schmidt, R. C., & O’Brien, B. (1997). Evaluating the dynamics of unintended interpersonal coordination. Ecological Psychology, 9, 189-206.
Schmidt, R. C., & Richardson, M. J. (2008). Dynamics of Interpersonal Coordination. In A. Fuchs & V. Jirsa (Eds.). Coordination: Neural, Behavioral and Social Dynamics. (pp. 281-308). Heidelberg: Springer-Verlag.
Schmidt, R. C., & Turvey, M. T. (1994). Phase-entrainment dynamics of visually coupled rhythmic movements. Biological Cybernetics, 70, 369-376.
Schmidt, R. C., Carello, C., & Turvey, M. T. (1990). Phase transitions and critical fluctuations in the visual coordination of rhythmic movements between people. Journal of Experimental Psychology: Human Perception and Performance, 16, 227-247.
Schmidt, R. C., Christianson, N., Carello, C., Baron, R. (1994) Effects of social and physical variables on between-person visual coordination. Ecological Psychology, 6, 159–183.
Schmidt, R. C., Richardson, M. J., ˠ Arsenault, C., & Galantucci, B. (2007). Visual Tracking and Entrainment to an Environmental Rhythm. Journal of Experimental Psychology: Human Perception and Performance. 33, 860-870.
Varlet, M., & Richardson, M. J. (2015). What Would Be Usain Bolt’s 100-Meter Sprint World Record Without Tyson Gay? Unintentional Interpersonal Synchronization Between the Two Sprinters. Journal of Experimental Psychology: Human Perception and Performance, 41, 36-41.
Varlet, M., Bucci, C., Richardson, M. J. & Schmidt, R. C. (2015). Informational Constraints on Spontaneous Visuomotor Entrainment. Human Movement Science.41, 265–281.
Washburn, A. Coey, C. A., Romero, V. & Richardson, M. J. (2014). Unintentional Polyrhythmic Entrainment: Can 1:2, 2:3 and 3:4 Patterns of Visual Coordination Occur Spontaneously? Journal of Motor Control, 46, 247-57.
Washburn, A., DeMarco, M., de Vries, S., Ariyabuddhiphongs, K., Schmidt, R. C., Richardson, M. J., & Riley, M. A. (2014). Dancers Entrain More Effectively than Non-Dancers to Another Actor’s Movements. Frontiers in Human Neuroscience. doi: 10.3389/fnhum.2014.00800.