The influence of a conductor and co-performer on auditory-motor synchronisation, temporal prediction, and ancillary entrainment in a musical drumming task.

Interpersonal coordination is exemplified in ensemble musicians, who coordinate their actions deliberately in order to achieve temporal synchronisation in their performances. However, musicians also move parts of their bodies unintentionally or spontaneously, sometimes in ways that do not directly produce sound from their instruments. Musicians' movements-intentional or otherwise-provide visual signals to co-performers, which might facilitate temporal synchronisation. In large ensembles, a conductor also provides a visual cue, which has been shown to enhance synchronisation. In the present study, we tested how visual cues from a co-performer and a conductor affect processes of temporal anticipation, synchronisation, and ancillary movements in a sample of primarily non-musicians. We used a dyadic synchronisation drumming task, in which paired participants drummed to the beat of tempo-changing music. We manipulated visual access between partners and a virtual conductor. Results showed that the conductor improved synchronisation with the music, but synchrony with the music did not improve when partners could see each other. Temporal prediction was improved when partners saw the conductor, but not each other. Ancillary movements of the head were more synchronised between partners when they could see each other, and greater ancillary synchrony at beat-related frequencies of movement was associated with greater drumming synchrony. These results suggest that compatible audio-visual cues can improve intentional synchronisation, that ancillary movements are affected by seeing a partner, and that attended vs. incidental visual cues thus have partially dissociable effects on temporal coordination during joint action.