Proceedings of the Annual Meeting of the Cognitive Science Society

In Joint Action (JA) tasks, individuals must coordinate theiractions so as to achieve some desirable outcome at the group-level. Group function is an emergent outcome of ongoing,mutually constraining interactions between agents. Here weinvestigate JA in dyads of improvising jazz pianists. Partic-ipants’ musical output is recorded in one of two conditions:a real condition, in which two pianists improvise together asthey typically would, and a virtual condition, in which a singlepianist improvises along with a “ghost partner” – a recordingof another pianist taken from a previous real trial. The con-ditions are identical except for that in real trials subjects aremutually coupled to one another, whereas there is only unidi-rectional influence in virtual trials (i.e. recording to musician).We quantify ways in which the rhythmic structures sponta-neously produced in these improvisations is shaped by mutualcoupling of co-performers. Musical signatures of underlyingcoordination patterns are also shown to parallel the subjectiveexperience of improvisers, who preferred playing in trials withbidirectional influence despite not explicitly knowing whichcondition they had played in. These results illuminate howmutual coupling shapes emergent, group-level structure in thecreative, open-ended and fundamentally collaborative domainof expert musical improvisation.