Experimental data on behavioural synchrony, assessed through systematic manipulation of participants' movement, via finger tapping, button pressing and full-body bouncing. Research participants (university students) completed the movement tasks in the presence of others or at the same time as others, yielding baseline, synchronous, or asynchronous movement. Movement timing was controlled using individually directed auditory metronome cues, presented via headphones, that participants were instructed to follow. Participants' movement was then measured: tapping and button pressing were measured using computer keyboards and purpose-built electronic recording devices, and full-body bouncing was recorded using 3D motion tracking of passive reflective sensors placed on participants’ torsos and limbs. Experiments included secondary tasks designed to measure cognitive mechanisms theorised to emerge from interpersonal synchrony. For example, verbal reaction-time tasks to assess participants’ ease in identifying visual stimuli, manual reaction-time tasks to assess the speed and accuracy of participants’ memory for interpersonal movement task information, facial muscle activity recording and computer-administered rating scales to assess participants’ evaluations of stimuli related to interpersonal movement tasks. All experiments also included computer-administered surveys assessing interpersonal relations outcomes (liking and rapport between task partners)."Behavioural synchrony" occurs when two or more people move together in time and space. The importance of behavioural synchrony lies in its ability to support the formation and maintenance of social bonds: Being "in synch" with others boosts interpersonal rapport, connectedness, trust and cooperation; being out of synch with others thwarts these outcomes. To date, most research on synchrony has been directed toward documenting its outcomes (eg, liking, perceived similarity, cooperative success). The funded research will provide insight into when and why synchrony promotes these outcomes, yielding the first comprehensive account of synchrony. Synchrony will be manipulated and measured in a variety of ways: manipulated, for example, by having multiple participants nod in time to musical rhythms, tap their fingers in time to visual "pulses" presented on a computer screen, or march in time to auditory pulses; and measured, for example, by recording the relative timing of participants' finger taps or by tracking the timing and trajectories of participants' movements. The research will demonstrate that behavioural synchrony imbues even neutral targets (concepts, people) with positivity; facilitates attention, perception, and memory; and changes individuals’ representations of themselves and others to be more similar and more closely linked in memory.

All participants were recruited from the student population at the University of Birmingham, and all data collection was carried out in research laboratories on the university campus. Studies were advertised via the online experiment management system maintained by the School of Psychology; participants self-selected into experiments according to their interest, availability, and preference for compensation (research credit for Research Methods modules in Psychology versus cash). Data was obtained to reflect physical movement, cognitive activity, and feelings and impressions. Physical movement was assessed via tapping and button pressing (measured using computer keyboards and purpose-built electronic recording devices) and full-body bouncing (measured using 3D motion tracking of passive reflective sensors placed on participants’ torsos and limbs). The tapping and button pressing measures yield numerical data in the form of the timing of each button press. The bouncing measures yield numerical data that is much more complex; the equipment yields numbers reflecting the continuous assessment of participants’ movement across both vertical and horizontal planes, in reference to their stationary starting point; from these, the precise timing of the target part of the movement (for bouncing, the point at which the participant reaches the “bottom” part of the bounce before moving upward again) can be pinpointed. In all cases, these numerical data can be analysed on their own or in relation to the auditory cues that participants are meant to use to guide their movement. Cognitive activity was assessed using computerised reaction-time tasks recording the precise timing and accuracy of participants’ responses; in some cases, the computer program calculates whether each response is correct or incorrect, whereas in others this determination needs to be made off-line by the researcher. Feelings and impressions were assessed using computer-administered rating scales in which participants select a numerical value that corresponds, for example, to how much they liked the task and their task partner.