Mutual Adaptive Timing in Interpersonal Action Coordination

Coperformers in musical ensembles continuously adapt the timing of their actions to maintain interpersonal coordination. The current study used a dyadic finger-tapping task to investigate whether such mutual adaptive timing is predominated by assimilation (i.e., copying relative timing, akin to mimicry) or compensation (local error correction). Our task was intended to approximate the demands that arise when coperformers coordinate complementary parts with a rhythm section in an ensemble. In two experiments, paired musicians (the coperformers) were required to tap in alternation, in synchrony with an auditory pacing signal (the rhythm section). Serial dependencies between successive asynchronies produced by alternating individuals' taps relative to the pacing tones revealed greater evidence for temporal assimilation than compensation. By manipulating the availability of visual and auditory feedback across experiments, it was shown that this assimilation was strongest when coactors' taps triggered sounds, while the effects of visual information were negligible. These results suggest that interpersonal temporal assimilation was mediated by perception-action coupling in the auditory modality. Mutual temporal assimilation may facilitate coordination in musical ensembles by automatically increasing stylistic compatibility between coperformers, thereby assisting them to sound cohesive.Keywords: interpersonal coordination, sensorimotor synchronization, behavioral assimilationEveryday life typically entails the coordination of one's actions with those of other individuals. Such social interaction frequently requires specific relations in interpersonal movement timing to be produced, as is epitomized in musical ensemble performance (Keller, 2008; Repp, 2006). In ensembles, the actions of multiple individuals must be temporally coordinated in a specific manner in order for the group to produce sounds that give the impression of a coherent musical performance. Thus, each ensemble member temporally tunes his or her actions to those of coperformers. This process relies on sensitivity to deviations from temporal regularity, however subtle, which must be anticipated and reacted to by adjusting the timing of subsequent actions (Keller, 2008; Maduell & Wing, 2007). These adjustments are driven by adaptive timing mechanisms that allow an individual to alter his or her ongoing rhythmic behavior to accommodate the effects of another individ- ual's actions or other external events. The present study used a dyadic finger-tapping task to investigate mutual adaptive timing in interpersonal action coordination.Our aim was to examine mutual adaptive timing in a tightly controlled experimental setting that nevertheless captures some of the basic demands of temporal coordination between coperformers in musical ensembles. We were specifically interested in demands that arise when coperformers are required to produce complemen- tary actions (i.e., to produce different sounds at different times) in synchrony with a common underlying pulse. This situation is common in modern popular ensemble music (e.g., jazz, rock, and pop), where a "rhythm section" comprising instruments such as the bass guitar and drums provides a basic quasi-periodic pulse rela- tive to which rhythms produced by other instruments are timed. The basso continuo (a bass line performed by a keyboard instru- ment, often supported by another low-pitched instrument) served a similar function in Baroque and other early Western art music (Brendel, 2007). Members of the ensemble must coordinate their performance with this basic pulse, as well as with each other's sounds, to achieve a well-synchronized holistic musical interplay.However, synchrony is never (objectively) perfect in human music making owing to perceptual and motor constraints, errors, and uncertainty associated with aesthetically motivated timing deviations that coperformers introduce for expressive purposes (Rasch, 1988). …