Sensorimotor synchronization (SMS)-the temporal alignment of motor behavior with a rhythmic sensory stimulus-has been observed in a variety of species and sensory modalities ( Greenfield, 2005 Ravignani et al., 2014). – The multi-person adaptive metronome allows to study, in a controlled way, the factors that influence interpersonal synchronization and social bonding. – Auditory feedback about one’s own and others’ taps influences both motor synchrony and subjective experience, and interacts with metronome adaptivity. – Both individuals and groups benefit from an optimally adaptive metronome, regardless of their previous musical experience. – By varying the adaptivity of a metronome, we show that we can enhance group synchrony and subjective feelings of enjoyment. – To aid people in synchronizing with each other, we built an assistive device that adapts in real-time to groups of people tapping together. Further, it provides an open-source tool for studying such factors in a controlled way. Further, individuals who tapped less variably than the group (which only occurred ∼25% of the time) were more likely to feel “in the groove.” Overall, this work replicates previous single person adaptive metronome studies and extends them to group contexts, thereby contributing to our understanding of the temporal, auditory, psychological, and personal factors underlying interpersonal synchrony and subjective enjoyment during sensorimotor interaction. Nonetheless, individuals and groups benefitted from adaptivity, regardless of their musical sophistication. Exploratory analyses relating person-level variables to tapping performance showed that musical sophistication and trait sadness contributed to the degree to which an individual differed in tapping stability from the group.

In predicting enjoyment, we found an interaction between auditory feedback and metronome adaptivity, with increased enjoyment at optimal levels of adaptivity only with auditory feedback and a severe decrease in enjoyment at higher levels of adaptivity, especially without feedback. This same factor structure replicated across all experiments. Subjective ratings of being in the groove, in synchrony with the metronome, in synchrony with others, liking the task, and difficulty all reduced to one latent factor, which we termed enjoyment. In group experiments with auditory feedback, synchrony remained enhanced even at 70–100% adaptivity without feedback, synchrony at these high adaptivity levels returned to near baseline. In all experiments, tapper synchronization with the metronome was significantly enhanced with 25–50% adaptivity, compared to no adaptation.

Across five experiments-two single-tapper, and three group (four tapper) experiments, we analyzed the effects of metronome adaptivity (percent correction based on the immediately preceding tap-metronome asynchrony) and auditory feedback on tapping performance and subjective ratings. The adaptive metronome is implemented on Arduino Uno circuit boards, allowing for negligible temporal latency between tapper input and adaptive sonic output. Here, we introduce an assistive device-a multi-person adaptive metronome-to facilitate synchronization abilities. However, the degree to which individuals can synchronize with each other depends on their ability to perceive the timing of others’ actions and produce movements accordingly. Synchronization of movement enhances cooperation and trust between people. 6Department of Psychology, University of California, Davis, Davis, CA, United States.5Center for Neuroscience, University of California, Davis, Davis, CA, United States.4Max Planck – NYU Center for Language, Music, and Emotion (CLaME), Frankfurt am Main, Germany.3Department of Music, Max Planck Institute for Empirical Aesthetics, Frankfurt am Main, Germany.2Neuroscience Graduate Group, University of California, Davis, Davis, CA, United States.1Center for Mind and Brain, University of California, Davis, Davis, CA, United States.

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