Patterns of Cooperative Rhythm Production Between One Leader and Two Followers Through Auditory and Visual Information

In a musical ensemble performance such as an orchestra, people synchronize tempo and timing with others using visual and auditory information. The synchronization/rhythmic pattern creation problems have long been studied in cognitive psychology[1], and more recently, also in complexity science. However, cooperative rhythm production (i.e., multiple people produce rhythm together), especially among three people (and more), has thus far remain insufficiently studied. Three-persons synchronization is obviously not just a sum of two-persons ones. We conducted alternate tapping experiments, in which each group of three participants was instructed to tap a pressure sensor alternately to keep a constant rhythm. A group consisted of one leader and two followers, and the leader was asked to maintain the pre-indicated tempo, whereas the two followers simultaneously synchronized with the leader. A Leader's tap was presented to the followers as a visual or auditory stimulus, and a followers' tap was presented to the leader and the other follower as an auditory stimulus. Our specific foci were on (i) how important the other follower's information for a follower is when syncing to a leader, and (ii) which kind of stimuli, visual or auditory, may be better for leaders to maintain the tempo. Through the experiments, we found that the groups that managed to maintain tempo had mainly two particular patterns of interdependency between the leader and the follower (see Figure). Here, we consider that A was dependent on B when A was influenced by the previous taps of B and performed the next tapping to correct the timing shift with B. Pattern (a), in which two followers are strongly dependent on a leader (= what was supposed to happen), was observed in both cases of when the leader's taps were presented as visual stimuli and when presented as audio stimuli. Interestingly, Pattern (b) (two followers are strongly dependent on each other) was also observed when visual stimuli were used. That is, even though two followers were not syncing so well with the leader, they could still manage to maintain the rhythm by syncing "locally" between the followers. This result suggests that, in an orchestra, it can be useful to match the timing first on a part-by-part basis, and then to match the overall timing by looking at the conductor.