Spontaneous Group Synchronization of Movements and Respiratory Rhythms

Abstract

We tested whether pre-assigned arm movements performed in a group setting spontaneously synchronized and whether synchronization extended to heart and respiratory rhythms. We monitored arm movements, respiration and electrocardiogram at rest and during spontaneous, music and metronome-associated arm-swinging. No directions were given on whether or how the arm swinging were to be synchronized between participants or with the external cues. Synchronization within 3 groups of 10 participants studied collectively was compared with pseudo-synchronization of 3 groups of 10 participants that underwent an identical protocol but in an individual setting. Motor synchronization was found to be higher in the collective groups than in the individuals for the metronome-associated condition. On a repetition of the protocol on the following day, motor synchronization in the collective groups extended to the spontaneous, un-cued condition. Breathing was also more synchronized in the collective groups than in the individuals, particularly at rest and in the music-associated condition. Group synchronization occurs without explicit instructions, and involves both movements and respiratory control rhythms.

Synchrony in positive social relationships

“…Physiological synchrony has also been observed between romantic partners (Helm, Sbarra, & Ferrer, 2012). Similarly, a study of group arm-waving showed that participants' respiratory rhythms synchronized with others in the group when arm movements were also synchronized (Codrons, Bernardi, Vandoni, & Bernardi, 2014). Physiological synchrony also emerges in a variety of other interpersonal contexts, including heart rate and respiratory synchronization between mother and fetus (Van Leeuwen et al, 2009), choir singers singing in unison compared to singing different parts of a piece in unison (Müller & Lindenberger, 2011), and participants and observers of collective rituals (e.g., fire-walking ritual; Konvalinka et al, 2011).…”

Influences on and Measures of Unintentional Group Synchrony

“…Similarly, Codrons et al (2014) assessed the influence of other people’s presence on movement and autonomic coordination across individuals in the absence of explicit cues to synchronize. Groups of 10 participants each performed an arm lifting motion without instructions on whether to synchronize to an external auditory rhythm (i.e., metronome beat or music excerpt).…”

“…With generalized partial directed coherence (Schelter et al, 2009; Codrons et al, 2014), a partial coherence spectrum plot, which represents the degree of similarity between time courses as a function of frequency while controlling for the influence of other participants, is first created for each pair of participants. Coherence values are then averaged for each plot (i.e., pair) and in turn averaged across all pairs for each condition.…”

Verbal Synchrony and Action Dynamics in Large Groups

“…Rhythmic and coordinated actions such as marching, dancing, singing, or playing music together have been part of human rituals across all cultures in the world (McNeill, 1995; Codrons et al, 2014), but synchrony is not only a human phenomenon. It can be found everywhere in the natural world as well.…”

“…For instance, do the effects of coordination scale up from pairs of people to small and then large groups? With a few exceptions (e.g., Wiltermuth and Heath, 2009; Reddish et al, 2013; Codrons et al, 2014; Tarr et al, 2015), behavioral coordination has mostly been studied in pairs, which makes it difficult to generalize from two people to large groups of people. These studies have also mostly studied the effects of coordinated movement.…”