Agency and Rhythmic Coordination: Are We Naught but Moving Dots?

There is contention in perceptual-motor research concerning the degree to which observing biological and non-biological movements have equivalent effects on movement production. This issue results from the proposal that action observation and production share neural resources (i.e., mirror neurons) particularly sensitive to actions performed by other ‘agents’ (i.e., beings with goals/intentions). In support of this claim, several discrete and rhythmic action-observation studies found that action production is only affected when participants believed that observed actions were produced by an agent. Here we present data from two experiments investigating whether similar agency manipulations also affect spontaneous movement synchrony. Collectively, the results suggest that belief in the ‘agency’ of an observed movement does not affect the emergence and stability of rhythmic movement synchrony. These results question whether the actions of other agents are truly privileged across all scales of coordinated activity, particularly with respect to the lawful dynamics underlying movement synchrony. Introduction In our everyday lives, we sustain complex states of coordination. On our way to work we coordinate our actions with our fellow commuters as we jostle for position in rush hour traffic. At work we coordinate our ideas with our colleagues as we develop a new product, policy, or program. Once home for the evening we coordinate with the clock to ensure we are well-rested enough to do it all over again the next day. Certainly, a complete account of coordination should aim at an explanation of these multi-scale, dynamic processes. Rather than attempting to reduce the full complexity of these phenomena to a sole, dominant process, an alternative approach is to gain an understanding of the nested processes that underlie such coordinated activity. It is in this spirit that researchers have investigated the lawful dynamics of rhythmic movement coordination (e.g., Kelso, 1995; Kugler & Turvey, 1987; Schmidt & Richardson, 2008). Dynamics of Rhythmic Coordination: Systems of coupled oscillators (e.g., human limbs, pendulums, etc.) generally exhibit similar coordination dynamics regardless of the constitution of the system in question. Early research (Haken et al., 1985; Kelso, 1984; Schöner et al., 1986) demonstrated that rhythmic movements of oscillatory limbs belonging to the same individual (e.g., fingers, arms, legs) exhibited two stable modes of entrainment, namely inphase and antiphase coordination. These two coordination modes are captured by the collective variable relative phase (Φ), with inphase and antiphase coordination corresponding to Φ = 0 ° and Φ = 180 ° , respectively. These two modes of coordination are intrinsically stable (are produced without practice), although antiphase coordination is less stable than inphase coordination. This difference in the relative stability of inphase and antiphase coordination is reflected by the fact that the variability of antiphase coordination is greater than the variability of inphase coordination and that individual’s transition from antiphase to the inphase coordination under certain movement conditions (i.e., high movement frequencies). More recent research has demonstrated the same coordination dynamics constrain oscillatory movements produced by separate individuals (e.g., Richardson et al., 2007; Schmidt et al., 1990; Schmidt & O’Brien, 1997). Provided a visual coupling, the coordination that occurs between the movements of two individuals is constrained to inphase and antiphase patterns of coordination (without practice), with antiphase being less stable than inphase coordination (e.g., Richardson, et al., 2007; Schmidt et al., 1990). Research has further demonstrated that similar coordination dynamics can occur spontaneously (i.e., unintentionally), with the rhythmic movements of two visually coupled participants become coordinated even when they are