Interpersonal Coordination

Common ground is a problematic concept. It is a necessary part of any pragmatic theory because it names the context that speakers take for granted in carrying out a communicative act, or in other words the background against which a signal shows up as a particular pattern of sounds or shapes, words, and social effects. But it is too often either ignored or treated as a stative body of information, a definition which makes it impossible to understand how common ground is used and instantiated in actual conversations. This essay remedies this problem by presenting a novel account of common ground which subsumes most extant theories by approaching the topic separately on each of three levels of explanation. I begin by presenting a dynamical definition of common ground based on elements of Stalnaker’s theory of speaker presupposition, on which common ground is the information presented by a speaker as not-at-issue in the process of carrying out some speech act. I then justify and enrich this approach with a psycholinguistic account of the uses of common ground in conversation based on Clark’s work on joint action, and show that common ground underlies both egocentric and cooperative communication. I then justify and enrich the psycholinguistic account by showing how it is instantiated on a biological level as intra- and interpersonal synergies in a conversation. Finally, I use an analysis of referring to illustrate the relations between these three levels of description, which between presupposition and joint action and between joint action and synergies I take to be one of coherence, clarification, and specifying the object of explanation. In the other direction - from synergies to joint action and joint action to presupposition - the relation is one of grounding and providing naturalistic credentials via mechanistic details. The originality and generality of this explanatory strategy suggest tremendous opportunities for pragmatic research from a dynamical perspective.

In combat sports, athletes continuously co-adapt their behavior to that of the opponent. We consider this interactive aspect of combat to be at the heart of skilled performance, yet combat sports research often neglects or limits interaction between combatants. To promote a more interactive approach, the aim of this paper is to understand combat sports from the combined perspective of ecological psychology and dynamic systems. Accordingly, combat athletes are driven by perception of affordances to attack and defend. Two combatants in a fight self-organize into one interpersonal synergy, where the perceptions and actions of both athletes are coupled. To be successful in combat, performers need to manipulate and take advantage of the (in)stability of the system. Skilled performance in combat sports therefore requires brinkmanship: combatants need to be aware of their action boundaries and purposefully act in meta-stable regions on the limits of their capabilities. We review the experimental literature to provide initial support for a synergetic approach to combat sports. Expert combatants seem able to accurately perceive action boundaries for themselves and their opponent. Local-level behavior of individual combatants has been found to lead to spatiotemporal synchronization at the global level of a fight. Yet, a formal understanding of combat as a dynamic system starting with the identification of order and control parameters is still lacking. We conclude that the ecological dynamics perspective offers a promising approach to further our understanding of skilled performance in combat sports, as well as to assist coaches and athletes to promote optimal training and learning.

Coordinated behavior promotes collaboration among humans. To shed light upon this relationship, we investigated whether and how interpersonal coordination is promoted by empathic perspective taking (EPT). In a joint music-making task, pairs of participants rotated electronic music-boxes, producing two streams of musical sounds that were meant to be played synchronously. Participants-who were not musically trained-were assigned to high and low EPT groups based on pre-experimental assessments using a standardized personality questionnaire. Results indicated that high EPT pairs were generally more accurate in synchronizing their actions. When instructed to lead the interaction, high and low EPT leaders were equally cooperative with followers, making their performance tempo more regular, presumably in order to increase their predictability and help followers to synchronize. Crucially, however, high EPT followers were better able to use this information to predict leaders' behavior and thus improve interpersonal synchronization. Thus, empathic perspective taking promotes interpersonal coordination by enhancing accuracy in predicting others' behavior while leaving the aptitude for cooperation unaltered. We argue that such predictive capacity relies on a sensorimotor mechanism responsible for simulating others' actions in an anticipatory manner, leading to behavioral advantages that may impact social cognition on a broad scale. Synchronous behavior is a universal means of communication and cooperation observable in diverse species 1-4. In humans, this kind of behavior can be witnessed during activities such as audiences clapping their hands in unison, military units marching, or groups of athletes or dancers coordinating their movements in space and time 5-9. Joint music making is a pervasive example of this phenomenon 10. Even a group of perfect strangers might end up singing together, for example during a competitive sporting game or a religious ritual-more likely so if the individuals support the same team, or believe in the same god, of course. When multiple individuals coordinate their movements in order to achieve interpersonal synchrony, the group benefits in terms of enhanced interpersonal bonding and social cohesion 11,12. Such pro-social effects of interpersonal synchronization have been reported in numerous laboratory studies using a variety of tasks 13-23. For instance, dyadic finger tapping in synchrony is more likely to increase feelings of affiliation 18 , trust, and likeability 16,24. These effects appear early in ontogenetic development, as evidenced by the finding that 14-month old infants, if moved in synchrony with another individual by an experimenter, are subsequently more likely to engage in cooperative helping behavior with that individual 19,25. Even the mere observation of synchronous group behavior can augment perceived social cohesion 26,27. These previous studies demonstrated that interpersonal synchrony is a sufficient condition to boost inter-personal pro-social processes. However, this is only one part of the story. Complementarily to these observations , some studies have shown that social personality traits can also affect interpersonal coordination skills. For instance, in one study, it was reported that individuals affected by Social Anxiety Disorder are impaired in leading a task requiring interpersonal coordination 28. Another study showed that individuals who have high internal Locus of Control (according to a questionnaire assessing to what extent individuals assume life events to be contingent on their personal behavior) are relatively good leaders in the sense that they prioritize stabilizing their own action timing over synchronization with an unreliable virtual partner 29. Taken alongside the above evidence, these results suggest that the link between synchrony and prosociality might be bidirectional: increased

Authors: Riccardo Fusaroli, Ivana Konvalinka, Sebastian Wallot

The scientific investigation of social interactions presents substantial challenges: interacting agents engage each other at many different levels and timescales (motor and physiological coordination, joint attention, linguistic exchanges, etc.), often making their behaviors interdependent in non-linear ways. In this paper we review the current use of Cross Recurrence Quantification Analysis (CRQA) in the analysis of social interactions, and assess its potential and challenges. We argue that the method can sensitively grasp the dynamics of human interactions, and that it has started producing valuable knowledge about them. However, much work is still necessary: more systematic analyses and interpretation of the recurrence indexes and more consistent reporting of the results, more emphasis on theory-driven studies, exploring interactions involving more than 2 agents and multiple aspects of coordination, and assessing and quantifying complementary coordinative mechanisms. These challenges are discussed and operationalized in recommendations to further develop the field.

Recent changes in the views on cognition underscore its embodied, situated and distributed character. These changes are compatible with the conceptual framework of ecological psychology. However for ecological psychology to propose explanations for a broad range of cognitive phenomena, including language, it needs an account of how to link dynamics of coupling between the organism and the environment with the apparent symbolicity of informational structures. In this paper it is proposed that a theory of information in biological systems, advocated by Howard Pattee, may help forge this link. By treating informational structures as constraints on dynamics this approach helps identifying which processes, in which systems and on what time-scales are needed for structures to ‘become messages’. I will illustrate how these processes might work on developmental time-scale building on the work by Ed Reed (1995, 1996) and extending it using the view of linguistic structures as constraints.

The current study evaluates how lexical choice impacts task performance in dyads tasked with building an object together without a shared visual environment. Our analyses suggest that, while interpersonal lexical convergence in target linguistic categories promotes successful communication, success does not require convergence in all categories. In the absence of shared visual workspaces and face-to-face communication, success increases when interlocutors converge in establishing common ground but decreases with increased co-occurrence of knowledge-state words, perhaps due to mutual hedging and uncertainty. Finally, miscommunication increases with use of ambiguous spatial terms and with markers of confusion, pointing to unique lexical signatures for successful and unsuccessful communication.

We focus on a fundamental looking behavior in human-robot interactions—gazing at each other's face. Eye contact and mutual gaze between two social partners are critical in smooth human-human interactions. Therefore, investigating at what moments and in what ways a robot should look at a human user's face as a response to the human's gaze behavior is an important topic. Toward this goal, we developed a gaze-contingent human-robot interaction system, which relied on momentary gaze behaviors from a human user to control an interacting robot in real time. Using this system, we conducted an experiment in which human participants interacted with the robot in a joint-attention task. In the experiment, we systematically manipulated the robot's gaze toward the human partner's face in real time and then analyzed the human's gaze behavior as a response to the robot's gaze behavior. We found that more face looks from the robot led to more look-backs (to the robot's face) from human participants, and consequently, created more mutual gaze and eye contact between the two. Moreover, participants demonstrated more coordinated and synchronized multimodal behaviors between speech and gaze when more eye contact was successfully established and maintained.

In conversation, speakers and listeners coordinate both their behavior and their mental states. Multi--brain studies, which record and relate to each other the neural activity of two or more brains, can provide insights into a coordination of neural states between communicating individuals. In this chapter we review recent multi--brain studies using functional magnetic resonance imaging (fMRI) or electroencephalography (EEG) to investigate verbal and nonverbal communication. We summarize common findings with respect to spatial and temporal aspects of inter--brain coordination. We then critically discuss challenges arising from studying dialogue in ecologically valid, yet experimentally controlled neuroscientific settings. We conclude by providing an outlook how technical and methodological advances may enable future multi-brain studies to better address these challenges.

The current paper presents two studies that examine how we compensate for asymmetries during interpersonal coordination. It was predicted that destabilizing effects of asymmetries are offset through the recruitment and suppression of motor degrees-offreedom (df). In Experiment 1, this effect was examined by having participants coordinate line movements of different orientations. Greater asymmetries between participants yielded greater spatial deviation from the intended orientation, suggesting a recruitment of df. In Experiment 2, participants coordinated circle and line movements. Results showed that line became more circular and circles became more linear, specifically along the axis of the line movements. These results suggested that df were both systematically suppressed (in the case of circle movements) and recruited (in the case of line movements) to stabilize an asymmetric coordination task.

This research investigated the role of interpersonal coordination in promoting positive affect in social interaction.  We propose that positive affect signifies that coordination in service of goal attainment has been achieved and strengthens social ties to maintain relationships characterized by effective coordination.  In two experiments, participants performed a virtual task on a computer in tandem with a bogus co-actor, whose behavior was generated by a computer program.  In Experiment 1, successful performance on a complex task required behavior coordination.  In Experiment 2, behavioral coordination was manipulated independently of successful performance.  Results showed that behavioral coordination promotes liking (Experiment 1) and that this effect is manifest under success but not failure (Experiment 2). Discussion centers on the adaptive value of behavioral and emotional coordination, the link between coordination and other psychological processes, and the conditions that promote versus hinder the attainment of such interaction fluency.

Coordination is an important part of successful movements in daily life and sports. The aim of this study was to investigate the effect of different levels of cognitive activities on intrapersonal and interpersonal motor coordination in taekwondo athletes (Poomsae). The population consisted of Poomsae male athletes in Tehran city. 30 individual Poomsae athletes and 30 team Poomsae athletes (age range: 17 - 30 years old) were selected by convenience sampling method. The sample was divided into 3 groups: control, easy cognitive activities and difficult cognitive activities. The control group only performed the motor coordination task whereas the cognitive groups performed the dual task. The results of one-way ANOVA test showed a significant difference for two handed (P=0.003) and two legged (P=0.04) coordination in total time factor (speed). Also, there was a significant difference in the error percentage factor for interpersonal motor coordination (P=0.02). In a two by two group analysis, the easy (P=0.003) and difficult (P=0.001) cognitive activities groups in two handed motor coordination and the difficult cognitive activities group in two legged (P=0.02) and interpersonal (P=0.01) motor coordination performed better than the control group. It is suggested that difficult activities should be used in addition to regular physical activities.

Analysis of coordinated interpersonal timing has become an important tool for the study of infant-adult, peer, and marital interactions. Past research suggests that social coordination is informative about the quality of the caregiver-child social relationship. Does infant experience of certain types of coordination and pattern in early social interactions with caregivers predict better cognitive and social developmental outcomes? The recent

What is the proper unit of analysis in the psycholinguistics of dialog? While classical approaches are largely based on models of individual linguistic processing, recent advances stress the social coordinative nature of dialog. In the influential interactive alignment model, dialogue is thus approached as the progressive entrainment of interlocutors' linguistic behaviors toward the alignment of situation models. Still, the driving mechanisms are attributed to individual cognition in the form of automatic structural priming. Challenging these ideas, we outline a dynamical framework for studying dialog based on the notion of interpersonal synergy. Crucial to this synergetic model is the emphasis on dialog as an emergent, self-organizing, interpersonal system capable of functional coordination. A consequence of this model is that linguistic processes cannot be reduced to the workings of individual cognitive systems but must be approached also at the interpersonal level. From the synergy model follows a number of new predictions: beyond simple synchrony, good dialog affords complementary dynamics, constrained by contextual sensitivity and functional specificity. We substantiate our arguments by reference to recent empirical studies supporting the idea of dialog as interpersonal synergy.

This article aims to explore how a joint rhythm is learned. The exploration is based on a combination of a case study of training in elite rowing and theoretical considerations concerning mutual incorporation of skills in learning. In 2009 Juliane and Anne start to row the double scull together. The two rowers’ aim is to be among the exclusive group of teams that qualify for the Olympic Games three years later. However, Anne is not a rower, and has to be apprenticed by Juliane, who is an experienced elite rower. One important learning goal in the apprenticeship is to find a good joint rhythm, which will enable the rowers to put optimal effort into the rowing. Thus the apprenticeship is about developing a sense for a good rhythm in Anne which corresponds to Juliane’s finely tuned sense of what a good rhythm should feel like. Our study suggests that apprenticeship learning has to be understood as an embodied and mutually affecting process rather than as unidirectional exchanges of inf...

Measuring instrument of interpersonal and intrapersonal motor coordination has designed and built to provide information about the human movements' coordination in reach of researchers, trainers and therapists. To evaluate the validation of this instrument with using of Vienna two hands coordination test and present research instrument were asked 28 participants to do the task of two hands, two feet and interpersonal movement coordination. Pearson correlation test showed that the present research instrument has high validation in motor coordination of two hands in total time mean factor of joystick (r =0/88), knob (r =0/96) and in error percentage mean factor of joystick (r =0/89) and knob (r =0/87). Also the results of Cronbach's alpha showed that present research instrument has appropriate reliability in motor coordination of two hands in total time mean factor of joystick (r =0/89) and knob (r =0/97) and in error time percentage mean factor of joystick (r =0/81) and knob (r =0/85). Also results indicated acceptable reliability in motor coordination of two feet in total time mean factor of pedals (r =0/90) and in error time percentage mean factor of pedals (r =0/83) and in interpersonal motor coordination in total time mean factor (r =0/91) and in error time percentage mean factor (r =0/80). Therefore using the present study instrument can be offered to sports science laboratories in all higher education institutions, federations and coaches, patients and rehabilitation centers, health and physiotherapy clinics.

Interest is rapidly growing in the hypothesis that natural language emerged from a more primitive set of linguistic acts based primarily on manual activity and hand gestures. Increasingly, researchers are investigating how hemispheric asymmetries are related to attentional and manual asymmetries (i.e., handedness). Both speech perception and production have origins in the dynamical generative movements of the vocal tract known as articulatory gestures. Thus, the notion of a ''gesture'' can be extended to both hand movements and speech articulation. The generative actions of the hands and vocal tract can therefore provide a basis for the (direct) perception of linguistic acts. Such gestures are best described using the methods of dynamical systems analysis since both perception and production can be described using the same commensurate language. Experiments were conducted using a phase transition paradigm to examine the coordination of speech-hand gestures in both left-and right-handed individuals. Results address coordination (in-phase vs. anti-phase), hand (left vs. right), lateralization (left vs. right hemisphere), focus of attention (speech vs. tapping), and how dynamical constraints provide a foundation for human communicative acts. Predictions from the asymmetric HKB equation confirm the attentional basis of functional asymmetry. Of significance is a new understanding of the role of perceived synchrony (p-centres) during intentional cases of gestural coordination.

Humans, as social beings, are capable of employing various behavioral cues, such as gaze, speech, manual action, and body posture, in everyday communication. However, to extract fine-grained interaction patterns in social contexts has been presented with methodological challenges. Cross-Recurrence Plot Quantification Analysis (CRQA) is an analysis method invented in theoretical physics and recently applied to cognitive science to study interpersonal coordination. In this paper, we extend this approach to analyzing joint activities in child-parent interaction. We define a new representation as Cross Recurrence Block based on CRQA. With this representation, we are able to capture interpersonal dynamics from more than two behavioral streams in one Cross Recurrence Plot and derive a suite of measures to quantify detailed characteristics of coordination. Using a data set collected from a child-parent interaction study, we show that these quantitative measures of joint activities reveal developmental changes in coordinative behavioral patterns between children and parents.

A coordinated rhythmic movement pattern is a dynamical activity involving many hidden layers of rhythmic subtasks. To investigate this dynamical substructure, spectroscopic concepts and methods were applied to an interlimb rhythmic movement task requiring 1:1 frequency locking of two hand-held pendulums in 180 degrees phase relation. The pendulums could be of identical or very different dimensions, thereby providing different values of the ratio omega of uncoupled frequencies. Analyses focused on the power spectrum of continuous relative phase as a function of variation in omega. Predictions were derived from the theories of mode locking and fractal time. Experimental results were in agreement with theoretical expectations and were discussed in terms of the possible recruiting of rhythmic subtasks in the assembling of interlimb absolute coordination, the interdependence of these subtasks, and the general dynamical principles that relate coordinative processes occurring at different length and time scales.

Successfully meeting a shared goal usually requires co-actors to adopt complementary roles. However, in many cases, who adopts what role is not explicitly predetermined, but instead emerges as a consequence of the differences in the individual abilities and constraints imposed upon each actor. Perhaps the most basic of roles are leader and follower. Here, we investigated the emergence of "leader-follower" dynamics in inter-personal coordination using a joint supra-postural task paradigm (Ramenzoni et al., 2011; Athreya et al., 2014). Pairs of actors were tasked with holding two objects in alignment (each actor manually controlled one of the objects) as they faced different demands for stance (stable vs. difficult) and control (which actor controlled the larger or smaller object). Our results indicate that when actors were in identical stances, neither led the inter-personal (between actors) coordination by any systematic fashion. Alternatively, when asymmetries in postural...

Analysis of coordinated interpersonal timing has become an important tool for the study of infant-adult, peer, and marital interactions. Past research suggests that social coordination is informative about the quality of the caregiver-child social relationship. Does infant experience of certain types of coordination and pattern in early social interactions with caregivers predict better cognitive and social developmental outcomes? The recent monograph " Rhythms of dialogue in infancy " (Jaffe, Beebe, Feldstein, Crown, & Jasnow, 2001) provides the strongest evidence to date that it does. Moderately coordinated social interactions in early infancy predicted the most favorable developmental outcomes, and degree of coordination was influenced by contextual factors such as setting and nature of the relationship between the infant and its social interaction partner. This study provides a model for future research in this area and points toward important questions for future research on infant-caregiver social interactions.

Research on interpersonal coordination has demonstrated that incongruent tasks lead to unintended movements in the orthogonal plane. These effects have been interpreted using both an embodied simulation and coordination dynamics approach. To distinguish between these two perspectives, two experiments examined whether this congruency effect is best defined spatially or anatomically. In the first experiment, participants coordinated congruent and incongruent rhythmic arm movements with an actor. To dissociate spatial and anatomical congruency, the actor was rotated 90°in the coronal plane for half of the trials. In the second experiment, participants coordinated movements of different limbs (leg and arm). Spatial and anatomical congruency was dissociated here by rotating the actor in the transverse plane. In both experiments, the unintended movements associated with the congruency effect emerged as a function of spatial congruency; there was no congruency effect associated with anatomical congruency. The data suggests that these unintended movements represent the recruitment of additional df necessary to stabilize an unstable form of coordination.

Some version of the construct of common ground is required in any pragmatic theory that relies on both (i) a distinction between what is said and what is meant and (ii) a representational model of meaning as internal and computational. On any such view, “common ground” is whatever premises are required to infer the mutually available but not explicitly articulated meaning of an utterance (Lee, 2001; Stalnaker, 2002).

By contrast, embodied and empirical approaches to common ground study coordination in gaze - on objects of shared attention - as well as coordination of body sway, prosody, and gesture (Shockley, Richardson, & Dale, 2009). This gives a concrete picture of what is perceptually and physically common in a meaning-rich interaction, but tells us little or nothing about conceptual and cultural common ground.

This paper takes some preliminary steps towards resolving this debate by dissolving the notion of common ground into the clearer notion of overlapping aspects of ecological embedding on multiple timescales, ranging from millisecond timescales for gaze and posture coordination up to multigenerational (i.e., cultural) timescales, for lexicogrammatical patterns and conceptual divisions (Thibault, 2011; Uryu, Steffensen, & Kramsch, 2014). This is a non-representational approach to utterance meaning that replaces the distinction between what is said and what is meant with that between which words were said and what effect those words have on the attentional activity of the interlocutors (c.f. Bach, 2001; Robertson, 2002).

With this in mind, the participatory negotiation of what is usually treated as common ground can instead be treated as coordinated action in a domain of attentional structures - not concepts per se, but non-local patterns or objects of experience to which we are able to direct our attention in virtue of our collaborative construction of a (partially) shared domain of attentional actions.

Background: One’s own motor system is activated by viewing and imaging another person performance. Purpose: The aim of this study was to investigate the motor simulation in prediction of interpersonal coordination among jumping rope elite boys. Methodology: An applied research was done as a single-stage case study with 14 jumping rope elite boys (13-18 years). The subjects practiced the jumping rope tasks (jumping rope in different distances and online landing) for four months, until they could do them properly and without any online feedbacks. This study used a Vicon motion analysis device with six infrared cameras capable of 120 frames per seconds to record three-dimensional movements of the legs and rope whirling. Results: The results of one-way ANOVA showed that with enough practice, movement onset time, hand-foot deviation time, timing variation in rope whirling, and landing time of joint groups were equal while a significant difference was observed in movement time and jump height between them (P≤0.05). Conclusion:) When people simulate a partner’s performance to do joint coordination, they may be relying on internal models that govern the interpersonal coordination. Indeed by increasing difficulty of task and so by increasing joint task demands, degree of interpersonal coordination would increase.

Dynamicity of natural human interaction, such as the incidence of overlaps, cause difficulties for creating man-machine dialogue systems [4]. Overlaps may lead either to continued talk (positive effect) or to interruptions (negative effect). The study is concerned with temporal organization of speech due to participants' interaction in natural discourse, based on Santa Barbara corpus of spoken American English [5]. The goal is to examine the ways speakers in a two-party conversation intuitively coordinate their production time through the lengths of turns, pauses, overlaps and interruptions. Cultural norms are based on acoustic data in homogeneous (both men; both women) and heterogeneous (man and woman) gender-related compositions of dyads. The basic findings: irrespective of the dyad's composition there is one dominant speaker who takes up twice as much speaking time, while the other party initiates most of the overlaps; in the mixed pairs women take the lead; the time limits for the overlaps before they turn into interruptions vary across the groups but the values are close for the two partners. Correlation analysis provides evidence of negative correlation between the total turn length and the number of overlaps and interruptions; between turn length and the length of overlaps and interruptions. Gender differences are significant with regards to the number of overlaps and interruptions, as well as turn length and the length of overlaps and interruptions. Women speak longer, whereas men overlap and interrupt more often.

Successfully meeting a shared goal usually requires co-actors to adopt complementary roles. However, in many cases, who adopts what role is not explicitly predetermined, but instead emerges as a consequence of the differences in the individual abilities and constraints imposed upon each actor. Perhaps the most basic of roles are leader and follower. Here, we investigated the emergence of " leader-follower " dynamics in inter-personal coordination using a joint supra-postural task paradigm (Ramenzoni et al., 2011; Athreya et al., 2014). Pairs of actors were tasked with holding two objects in alignment (each actor manually controlled one of the objects) as they faced different demands for stance (stable vs. difficult) and control (which actor controlled the larger or smaller object). Our results indicate that when actors were in identical stances, neither led the inter-personal (between actors) coordination by any systematic fashion. Alternatively, when asymmetries in postural demands were introduced, the actor with the more difficult stance led the coordination (as determined using cross-recurrence quantification analysis). Moreover, changes in individual stance difficulty resulted in similar changes in the structure of both intra-personal (individual) and inter-personal (dyadic) coordination, suggesting a scale invariance of the task dynamics. Implications for the study of interpersonal coordination are discussed.

A coordinated rhythmic movement pattern is a dynamical activity involving many hidden layers of rhythmic subtasks. To investigate this dynamical substructure, spectroscopic concepts and methods were applied to an interlimb rhythmic movement task requiring 1:1 frequency locking of two hand-held pendulums in 180" phase relation. The pendulums could be of identical or very different dimensions, thereby providing different values of the ratio fl of uncoupled frequencies.

What are the mapping mechanisms that enable people to synchronously imitate continuous action sequences observed in others? We investigated this question in four experiments that used a tapping task where participants synchronously performed alternating bimanual hand movements with a model presented in an egocentric or allocentric orientation. Their task was to tap in synchrony, with each hand matching the movements of the ipsilateral model hand as closely as possible. The results show that automatic establishment of topological mappings, where the performer´s hand is mapped onto the model´s anatomically matching hand even if the two are spatially misaligned, can interfere with maintaining spatial mappings (Experiment 1 and 2). The interference was particularly strong in musicians who have expertise in establishing topological mappings in continuous performance (Experiment 4). Adopting an unusual body posture greatly interfered with establishing spatial as well as topological mappings (Experiment 3). Together the results suggest that synchronous imitation of continuous action sequences depends on flexible predictive models that simultaneously apply spatial and topological mapping constraints to enable an actor to act in synchrony with observed action sequences.

The current study evaluates how lexical choice impacts task performance in dyads tasked with building an object together without a shared visual environment. Our analyses suggest that, while interpersonal lexical convergence in target linguistic categories promotes successful communication, success does not require convergence in all categories. In the absence of shared visual workspaces and face-to-face communication, success increases when interlocutors converge in establishing common ground but decreases with increased co-occurrence of knowledge-state words, perhaps due to mutual hedging and uncertainty. Finally, miscommunication increases with use of ambiguous spatial terms and with markers of confusion, pointing to unique lexical signatures for successful and unsuccessful communication.

Research on interpersonal coordination has demonstrated that incongruent tasks lead to unintended movements in the orthogonal plane. These effects have been interpreted using both an embodied simulation and coordination dynamics approach. To distinguish between these two perspectives, two experiments examined whether this congruency effect is best defined spatially or anatomically. In the first experiment, participants coordinated congruent and incongruent rhythmic arm movements with an actor. To dissociate spatial and anatomical congruency, the actor was rotated 90°in the coronal plane for half of the trials. In the second experiment, participants coordinated movements of different limbs (leg and arm). Spatial and anatomical congruency was dissociated here by rotating the actor in the transverse plane. In both experiments, the unintended movements associated with the congruency effect emerged as a function of spatial congruency; there was no congruency effect associated with anatomical congruency. The data suggests that these unintended movements represent the recruitment of additional df necessary to stabilize an unstable form of coordination.