Interpersonal Action Coordination Research Articles

Dynamics in interbrain synchronization while playing a piano duet.

Humans interact with each other through actions that are implemented by sensory and motor processes. To investigate the role of interbrain synchronization emerging during interpersonal action coordination, electroencephalography data from 13 pairs of pianists were recorded simultaneously while they performed a duet together. The study aimed to investigate whether interbrain phase couplings can be reduced to similar bottom-up driven processes during synchronous play, or rather represent cognitive top-down control required during periods of higher coordination demands. To induce such periods, one of the musicians acted as a confederate who deliberately desynchronized the play. As intended, on the behavioral level, the perturbation caused a breakdown in the synchronization of the musicians' play and in its stability across trials. On the brain level, interbrain synchrony, as measured by the interbrain phase coherence (IPC), increased in the delta and theta frequency bands during perturbation as compared to non-perturbed trials. Interestingly, this increase in IPC in the delta band was accompanied by the shift of the phase difference angle from in-phase toward anti-phase synchrony. In conclusion, the current study demonstrates that interbrain synchronization is based on the interpersonal temporal alignment of different brain mechanisms and is not simply reducible to similar sensory or motor responses.

Interpersonal synchrony when singing in a choir.

Singing in a choir has long been known to enhance well-being and protect mental health. Clearly, the experience of a uniquely harmonious social activity is very satisfying for the singers. How might this come about? One of the important factors positively associated with well-being is interpersonal action coordination allowing the choir to function as a whole. This review focuses on temporal coordination dynamics of physiological systems and/or subsystems forming part or the core of the functional substrate of choir singing. These coordination dynamics will be evaluated with respect to the concept of a superordinate system, or superorganism, based on the principles of self-organization and circular causality. We conclude that choral singing is a dynamic process requiring tight interpersonal action coordination that is characterized by coupled physiological systems and specific network topology dynamics, representing a potent biomarker for social interaction.

Electrophysiology of interoception: Parietal posterior area supports social synchronization

ABSTRACT The effect of explicit interoception manipulation on electrophysiological (EEG) patterns concurrent with an interpersonal motor synchronization task with a social purpose was investigated in this study. Thirty healthy individuals executed a task involving behavioral motor synchronization with a social framing in both focus (conceived as the focus on the breath for a specific time interval) and no focus conditions. During the task, a 15 active electrodes electroencephalogram was used to record the following frequency bands (delta, theta, alpha, and beta band) from the frontal, temporo-central, and parieto-occipital regions of interest (ROIs). According to the results, for all the frequency bands significant higher mean values were found in the focus compared to no focus condition in the parieto-occipital ROI. On the whole, the current work conveys that when a motor synchronization task is executed and the person concurrently pays attention to his/her body correlates, EEG brain activity is empowered and boosted in posterior areas at the basis of attention to visceral signals, but also interpersonal action coordination. This evidence could have potentially interesting implications because it suggests the importance of modern breath-work during all conditions that require a social motor joint task, such as physiotherapy exercises or synchronized sports.

The role of reciprocity in dynamic interpersonal coordination of physiological rhythms

A central question in social cognition research is how people coordinate their bodily rhythms, and how important reciprocity of interaction is for interpersonal coordination. Previous research has primarily focused on interpersonal action coordination, which has been shown to be facilitated by mechanisms of prediction and mutual adaption. Recent research is beginning to show that people also coordinate their physiological rhythms (i.e., respiration, heart rhythms) when they engage in natural forms of social interaction, such as conversation, choir singing, and rituals. However, the mechanisms underlying interpersonal physiological synchronization remain obscure, and could provide insight into the dynamic mechanisms that underlie continuous and regulatory, rather than instrumental, joint actions. Using real-time biofeedback, we investigated whether people synchronize their respiration rhythms by forming a joint dynamical system through reciprocity of interaction, or by producing more predictable respiration rhythms. Our results show that people are more in-phase synchronized but less phase-locked when interacting bidirectionally versus unidirectionally (online), but there is no difference in synchronization during reciprocal interaction and when adapting unidirectionally (offline) to recordings of respiration signals that emerged during the reciprocal interaction. Moreover, the strength of synchronization is driven by the predictability of the respiration rhythms that emerge in the bidirectional interaction – specifically, the slowing of breathing rhythms and stability of breathing frequencies – rather than the online mutual adaptation itself. These results suggest that coordination is facilitated by the emergence of predictable breathing patterns, rather than reciprocity itself.

Probing associations between interbrain synchronization and interpersonal action coordination during guitar playing

Playing music in an ensemble is a highly coordinated human action involving musicians' brain-body interactions at different levels of physical and cortical organization in time and space. It has been suggested that interbrain phase synchronization plays an essential role in musical interaction. In this study, we aimed to explore associations between interbrain synchronization and interpersonal action coordination, using electroencephalographic recordings of the brain activity of guitarists playing in a duet as well as the acoustic recordings of their music. By applying phase synchronization algorithms to the musicians' brain activities and the sounds produced during guitar playing, we show that synchronous brain activity is strongly related to instrument sounds and behavioral play-onset synchrony, as indicated by phase alignment in relation to the time differences in play onsets and an angular-linear correlation between phase and time differences across trials and guitarist pairs. Interestingly, this correlation was especially strong in the first part of the music piece, when the guitarists seem to adjust their coordinated play onsets and brain rhythms actively. This suggests that the methods capturing intra- and interbrain synchronization and its relations to coordinated playing provide crucial information about the underlying mechanisms of interpersonal action coordination.

Interacting brains coming in sync through their minds: an interbrain neurofeedback study.

Neurophysiological evidence shows that interpersonal action coordination is accompanied by interbrain synchronization (IBS). However, the functional significance of this association remains unclear. Using two experimental designs, we explored whether IBS is amenable to neurofeedback (NFB). Feedback was provided either as two balls approaching each other (so-called ball design), or as two pendula, each reflecting the oscillatory activity of one of the two participants (so-called pendulum design). The NFB was provided at delta (i.e., 2.5 Hz) and theta (i.e., 5Hz) electroencephalography frequencies, and manipulated by enhanced and inverse feedback. We showed that the participants were able to increase IBS by using NFB, especially when it was fed back at the theta frequency. Apart from intra- and interbrain coupling, other oscillatory activities (e.g., power spectral density, peak amplitude, and peak frequency) also changed during the task compared with the rest. Moreover, all the measures showed specific correlations with the subjective postsurvey item scores, reflecting subjective feeling and appraisal. We conclude that the use of IBS for NFB might help in specifying the contribution of IBS to interpersonal action coordination and in providing important information about the neural mechanisms of social interaction and the causal dimension of IBS.

Complex networks emerging during choir singing.

Choir singing is positively associated with well-being and quality of life, and requires the coordination of physiological systems within and across individuals. Informed by models of interpersonal action coordination, we delineate the network topography of choir singing by analyzing cross-frequency couplings and within-frequency couplings (WFCs) of respiratory, cardiac, vocalizing, and motor subsystems. We find that respiratory and cardiac subsystems synchronize with one another during singing and are coupled to oscillatory vocalizing patterns, and to the hand-movement oscillations of the choir's conductor. The choir's cross-frequency connections are particularly strong when singing a canon in parts, apparently supporting the interaction and coordination of the different canon entries. In contrast, WFCs are more pronounced when singing the same canon in unison. We conclude that the temporal coordination dynamics of the observed subsystems form part of the functional substrate for choir singing. During singing, the choir functions as a superordinate system, or superorganism, that imposes boundary conditions on the dynamic features of the individual singers.

Hyper-Transcranial Alternating Current Stimulation: Experimental Manipulation of Inter-Brain Synchrony.

We walk together, we watch together, we win together: Interpersonally coordinated actions are omnipresent in everyday life, yet the associated neural mechanisms are not well understood. Available evidence suggests that the synchronization of oscillatory activity across brains may provide a mechanism for the temporal alignment of actions between two or more individuals. In an attempt to provide a direct test of this hypothesis, we applied transcranial alternating current stimulation simultaneously to two individuals (hyper-tACS) who were asked to drum in synchrony at a set pace. Thirty-eight female-female dyads performed the dyadic drumming in the course of 3 weeks under three different hyper-tACS stimulation conditions: same-phase-same-frequency; different-phase-different-frequency; sham. Based on available evidence and theoretical considerations, stimulation was applied over right frontal and parietal sites in the theta frequency range. We predicted that same-phase-same-frequency stimulation would improve interpersonal action coordination, expressed as the degree of synchrony in dyadic drumming, relative to the other two conditions. Contrary to expectations, both the same-phase-same-frequency and the different-phase-different-frequency conditions were associated with greater dyadic drumming asynchrony relative to the sham condition. No influence of hyper-tACS on behavioral performance was seen when participants were asked to drum separately in synchrony to a metronome. Individual and dyad preferred drumming tempo was also unaffected by hyper-tACS. We discuss limitations of the present version of the hyper-tACS paradigm, and suggest avenues for future research.

Neural mirroring and social interaction: Motor system involvement during action observation relates to early peer cooperation

Whether we hand over objects to someone, play a team sport, or make music together, social interaction often involves interpersonal action coordination, both during instances of cooperation and entrainment. Neural mirroring is thought to play a crucial role in processing other’s actions and is therefore considered important for social interaction. Still, to date, it is unknown whether interindividual differences in neural mirroring play a role in interpersonal coordination during different instances of social interaction. A relation between neural mirroring and interpersonal coordination has particularly relevant implications for early childhood, since successful early interaction with peers is predictive of a more favorable social development. We examined the relation between neural mirroring and children’s interpersonal coordination during peer interaction using EEG and longitudinal behavioral data. Results showed that 4-year-old children with higher levels of motor system involvement during action observation (as indicated by lower beta-power) were more successful in early peer cooperation. This is the first evidence for a relation between motor system involvement during action observation and interpersonal coordination during other instances of social interaction. The findings suggest that interindividual differences in neural mirroring are related to interpersonal coordination and thus successful social interaction.

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 in an ensemble. In two experiments, paired musicians (the coperformers) were required to tap in alternation, in synchrony with an auditory pacing signal (the 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). …

Directionality in hyperbrain networks discriminates between leaders and followers in guitar duets.

To investigate whether directionality in hyperbrain networks reflects different roles during interpersonal action coordination (IAC), we recorded EEG data from pairs of guitarists playing together as musical leaders versus followers. We used an asymmetric index of in-phase synchronization to analyze hyperbrain networks of directed functional connectivity in the alpha and beta frequency ranges for time segments around coordinated play onsets. After exploring the small-world characteristics of the networks at different thresholds, we examined the directed connection strengths within and between brains. As predicted, we found evidence suggesting that the musical roles of leader and follower are associated with different patterns of directed between-brain couplings. The functional significance of these differences for IAC requires further study.

Neural correlates of auditory temporal predictions during sensorimotor synchronization

Musical ensemble performance requires temporally precise interpersonal action coordination. To play in synchrony, ensemble musicians presumably rely on anticipatory mechanisms that enable them to predict the timing of sounds produced by co-performers. Previous studies have shown that individuals differ in their ability to predict upcoming tempo changes in paced finger-tapping tasks (indexed by cross-correlations between tap timing and pacing events) and that the degree of such prediction influences the accuracy of sensorimotor synchronization (SMS) and interpersonal coordination in dyadic tapping tasks. The current functional magnetic resonance imaging study investigated the neural correlates of auditory temporal predictions during SMS in a within-subject design. Hemodynamic responses were recorded from 18 musicians while they tapped in synchrony with auditory sequences containing gradual tempo changes under conditions of varying cognitive load (achieved by a simultaneous visual n-back working-memory task comprising three levels of difficulty: observation only, 1-back, and 2-back object comparisons). Prediction ability during SMS decreased with increasing cognitive load. Results of a parametric analysis revealed that the generation of auditory temporal predictions during SMS recruits (1) a distributed network of cortico-cerebellar motor-related brain areas (left dorsal premotor and motor cortex, right lateral cerebellum, SMA proper and bilateral inferior parietal cortex) and (2) medial cortical areas (medial prefrontal cortex, posterior cingulate cortex). While the first network is presumably involved in basic sensory prediction, sensorimotor integration, motor timing, and temporal adaptation, activation in the second set of areas may be related to higher-level social-cognitive processes elicited during action coordination with auditory signals that resemble music performed by human agents.

The Influence of Visual Information on the Motor Control of Table Tennis Strokes

Theories of social interaction (i.e., common coding theory) suggest that visual information about the interaction partner is critical for successful interpersonal action coordination. Seeing the interaction partner allows an observer to understand and predict the interaction partner's behavior. However, it is unknown which of the many sources of visual information about an interaction partner (e.g., body, end effectors, and/or interaction objects) are used for action understanding and thus for the control of movements in response to observed actions. We used a novel immersive virtual environment to investigate this further. Specifically, we asked participants to perform table tennis strokes in response to table tennis balls stroked by a virtual table tennis player. We tested the effect of the visibility of the ball, the paddle, and the body of the virtual player on task performance and movement kinematics. Task performance was measured as the minimum distance between the center of the paddle and the center of the ball (radial error). Movement kinematics was measured as variability in the paddle speed of repeatedly executed table tennis strokes (stroke speed variability). We found that radial error was reduced when the ball was visible compared to invisible. However, seeing the body and/or the racket of the virtual players only reduced radial error when the ball was invisible. There was no influence of seeing the ball on stroke speed variability. However, we found that stroke speed variability was reduced when either the body or the paddle of the virtual player was visible. Importantly, the differences in stroke speed variability were largest in the moment when the virtual player hit the ball. This suggests that seeing the virtual player's body or paddle was important for preparing the stroke response. These results demonstrate for the first time that the online control of arm movements is coupled with visual body information about an opponent.

Cardiac and Respiratory Patterns Synchronize between Persons during Choir Singing

Dyadic and collective activities requiring temporally coordinated action are likely to be associated with cardiac and respiratory patterns that synchronize within and between people. However, the extent and functional significance of cardiac and respiratory between-person couplings have not been investigated thus far. Here, we report interpersonal oscillatory couplings among eleven singers and one conductor engaged in choir singing. We find that: (a) phase synchronization both in respiration and heart rate variability increase significantly during singing relative to a rest condition; (b) phase synchronization is higher when singing in unison than when singing pieces with multiple voice parts; (c) directed coupling measures are consistent with the presence of causal effects of the conductor on the singers at high modulation frequencies; (d) the different voices of the choir are reflected in network analyses of cardiac and respiratory activity based on graph theory. Our results suggest that oscillatory coupling of cardiac and respiratory patterns provide a physiological basis for interpersonal action coordination.

Understanding interpersonal action coordination: an fMRI study

Coordination of actions according to the request of another person is frequently observed in daily life. The purpose of this study is to elucidate the neural mechanisms related to the processing of this type of interpersonal action coordination by using functional magnetic resonance imaging (fMRI). In the first experiment, participants viewed movie clips depicting two people (1st and 3rd person) involved in a joint-action situation: one person (passive agent) holding two objects asked the other person to take one object; the other person (active agent) then performing a congruent or incongruent action with regard to the request. fMRI results showed that the right inferior frontal gyrus (IFG) and right cerebellum were more activated during the observation of incongruent actions than that of congruent actions. Greater activation in the right posterior superior temporal sulcus (pSTS) and the medial prefrontal cortex (mPFC) were also found in the same contrast after small volume correction (SVC). In the second experiment, in which only the active person appeared in the movie clip (single-action situation), no significant activation in the right IFG and right cerebellum was found, although greater activation in the right pSTS and the mPFC was found during the observation of the incongruent action than that of the congruent action after SVC. Our study suggests that the right IFG, which is assumed to be a part of the mirror neuron system, is involved in understanding interpersonal action congruency.

The role of temporal prediction abilities in interpersonal sensorimotor synchronization

Musical ensemble performance is a form of joint action that requires highly precise yet flexible interpersonal action coordination. To maintain synchrony during expressive passages that contain tempo variations, musicians presumably anticipate the sounds that will be produced by their co-performers. Our previous studies revealed that individuals differ in their ability to predict upcoming event timing when finger tapping in synchrony with tempo-changing pacing signals (i.e., the degree to which inter-tap intervals match vs. lag behind inter-onset intervals in the pacing signal varies between individuals). The current study examines the influence of these individual differences on synchronization performance in a dyadic tapping task. In addition, the stability of individual prediction tendencies across time is tested. Individuals with high or low prediction tendencies were invited to participate in two experimental sessions. In both sessions, participants were asked (1) to tap alone with a tempo-changing pacing signal and (2) to tap synchronously in dyads comprising individuals with similar or different prediction tendencies. Results indicated that individual differences in prediction tendencies were stable over several months and played a significant role in dyadic synchronization. Dyads composed of two high-predicting individuals tapped with higher accuracy and less variability than low-predicting dyads, while mixed dyads were intermediate. Prediction tendencies explained variance in dyadic synchronization performance over and above individual synchronization ability. These findings suggest that individual differences in temporal prediction ability may potentially mediate the interaction of cognitive, motor, and social processes underlying musical joint action.

Brains swinging in concert: cortical phase synchronization while playing guitar

BackgroundBrains interact with the world through actions that are implemented by sensory and motor processes. A substantial part of these interactions consists in synchronized goal-directed actions involving two or more individuals. Hyperscanning techniques for assessing fMRI simultaneously from two individuals have been developed. However, EEG recordings that permit the assessment of synchronized neuronal activities at much higher levels of temporal resolution have not yet been simultaneously assessed in multiple individuals and analyzed in the time-frequency domain. In this study, we simultaneously recorded EEG from the brains of each of eight pairs of guitarists playing a short melody together to explore the extent and the functional significance of synchronized cortical activity in the course of interpersonally coordinated actions.ResultsBy applying synchronization algorithms to intra- and interbrain analyses, we found that phase synchronization both within and between brains increased significantly during the periods of (i) preparatory metronome tempo setting and (ii) coordinated play onset. Phase alignment extracted from within-brain dynamics was related to behavioral play onset asynchrony between guitarists.ConclusionOur findings show that interpersonally coordinated actions are preceded and accompanied by between-brain oscillatory couplings. Presumably, these couplings reflect similarities in the temporal properties of the individuals' percepts and actions. Whether between-brain oscillatory couplings play a causal role in initiating and maintaining interpersonal action coordination needs to be clarified by further research.