Would you like to play together? Adults' attachment and the mirror game

New horizon in improving ageing with improvisational theatre

Cognitive decline, mental health and mindset factors can all affect the autonomy and well-being of older adults. As the number of older adults across the globe increases, interventions to improve well-being are urgently needed. Improvisational theatre (improv) and improv-based interventions are well-suited to address this need. Studies have shown that participation in improv-based interventions has a positive impact on mental health indicators, including depressive symptoms, well-being and social connectedness, as well as cognitive skills such as attention and memory. In addition, improv-based interventions have been beneficial for people with dementia, improving positive affect, self-esteem and communication. In this article, we describe improvisational theatre, or improv, and the reasons it has emerged from a form of spontaneous theatre that involves playfulness and creativity to an important tool to effect behavioural change in individuals and groups. We then review the literature on the effects of improv in ageing populations, with a focus on social, emotional and cognitive functioning. Finally, we make recommendations on designing improv-based interventions so that future research, using rigorous quantitative methods, larger sample sizes and randomised controlled trials, can expand the use of improv in addressing important factors related to autonomy and well-being in older adults.

Classifying interpersonal synchronization states using a data-driven approach: implications for social interaction understanding

This study presents a data-driven approach to identifying interpersonal motor synchrony states by analyzing hand movements captured from a 3D depth camera. Utilizing a single frame from the experiment, an XGBoost machine learning model was employed to differentiate between spontaneous and intentional synchrony modes with nearly [Formula: see text] accuracy. Our findings demonstrate a consistent pattern across subjects, revealing that movement velocity tends to be slower in synchrony modes. These insights support the notion that the relationship between velocity and synchrony is influenced by the cognitive load required for the task, with slower movements leading to higher synchrony in tasks demanding higher cognitive load. This work not only contributes to the limited literature on algorithms for identifying interpersonal synchrony but also has potential implications for developing new metrics to assess real-time human social interactions, understanding social interaction, and diagnosing and developing treatment strategies for social deficits associated with conditions such as Autism Spectrum Disorder.

Trait mindful awareness predicts inter-brain coupling but not individual brain responses during naturalistic face-to-face interactions

In recent years, the possible benefits of mindfulness meditation have sparked much public and academic interest. Mindfulness emphasizes cultivating awareness of our immediate experience and has been associated with compassion, empathy, and various other prosocial traits. However, neurobiological evidence pertaining to the prosocial benefits of mindfulness in social settings is sparse. In this study, we investigate neural correlates of trait mindful awareness during naturalistic dyadic interactions, using both intra-brain and inter-brain measures. We used the Muse headset, a portable electroencephalogram (EEG) device often used to support mindfulness meditation, to record brain activity from dyads as they engaged in naturalistic face-to-face interactions in a museum setting. While we did not replicate prior laboratory-based findings linking trait mindfulness to individual brain responses (N = 379 individuals), self-reported mindful awareness did predict dyadic inter-brain synchrony, in theta (~5–8 Hz) and beta frequencies (~26-27 Hz; N = 62 dyads). These findings underscore the importance of conducting social neuroscience research in ecological settings to enrich our understanding of how (multi-brain) neural correlates of social traits such as mindful awareness manifest during social interaction, while raising critical practical considerations regarding the viability of commercially available EEG systems.

Liking as a balance between synchronization, complexity and novelty

Synchronization has been identified as a key aspect in social bonding. While synchronization could be maximized by increasing the predictability of an interaction, such predictability is in tension with individuals’ level of interest, which is tied to the interaction’s complexity and novelty. In this study, we tested the interplay between synchronization and interest. We asked 104 female dyads to play the Mirror Game, in which they had to move their hands as coordinately as possible, and then report how much they liked each other. Utilizing information theory and video processing tools, we found that a combination of movement synchronization and complexity explained liking almost two times better than movement synchronization alone. Moreover, we found that people initiated novel and challenging interactions, even though they paid a price—being less synchronized. Examining the interactions’ dynamics, we found that people who liked each other moved in a more synchronized, complex, and novel manner during most of the interaction. This suggests that in addition to synchronization, maintaining interest may be critical for positive social bonding. Thus, we propose a new framework in which balancing synchronization and interest, rather than merely maximizing synchronization, optimizes the interaction quality.

Nonverbal Synchrony in Couple Therapy Linked to Clients' Well-Being and the Therapeutic Alliance

Nonverbal synchrony between individuals has a robust relation to the positive aspects of relationships. In psychotherapy, where talking is the cure, nonverbal synchrony has been related to a positive outcome of therapy and to a stronger therapeutic alliance between therapist and client in dyadic settings. Only a few studies have focused on nonverbal synchrony in multi-actor therapy conversations. Here, we studied the synchrony of head and body movements in couple therapy, with four participants present (spouses and two therapists). We analyzed more than 2000min of couple therapy videos from 11 couple therapy cases using Motion Energy Analysis and a Surrogate Synchrony (SUSY), a procedure used earlier in dyadic psychotherapy settings. SUSY was calculated for all six dyads per session, leading to synchrony computations for 66 different dyads. Significant synchrony occurred in all 29 analyzed sessions and between the majority of dyads. Complex models were used to determine the relations between nonverbal synchrony and the clients’ well-being and all participants’ evaluations of the therapeutic alliance. The clients’ well-being was related to body synchronies in the sessions. Differences were found between the clients’ and therapists’ alliance evaluations: the clients’ alliance evaluations were related to synchrony between both dyads of opposite gender, whereas the therapists’ alliance evaluations were related to synchrony between dyads of the same gender, but opposite to themselves. With four participants present, our study introduces a new aspect of nonverbal synchrony, since as a dyad synchronizes, the other two participants are observing it. Nonverbal synchrony seems to be as important in couple therapy as in individual psychotherapy, but the presence of multiple participants makes the patterns more complex.

The role of oxytocin in regulating loneliness in old age

Loneliness is prevalent in old age and is associated with reduced positive social interactions. Building on studies showing that oxytocin (OT) levels rise during social interactions, we hypothesized that following participation in positive social interaction involving synchronized movements, OT levels would increase, while state loneliness levels would diminish. A total of 63 older adults (aged M = 78.93, SD = 9.99; Range = 65-101) participated in the study. Participants completed emotional and social loneliness scales and provided saliva samples pre- and post-participation in the "mirror game", which requires movement synchronization and is known to promote connectedness and closeness. Results indicate a reduced state of loneliness following the mirror game. Importantly, the change in OT levels predicted the change in social loneliness, defined as the absence of social interactions with people in the social network. On the other hand, emotional loneliness, marked by deficient emotional contact, only decreased among participants who experienced high levels of closeness with their partner in the mirror game. Findings suggest that context-dependent change in endogenous OT may serve as biomarker for the social effects of oxytocin on loneliness in old age and can help in the development of targeted interventions for treating loneliness in old age.

Shifts in Behavioral Synchrony in Response to an Interaction Partner's Distress in Adolescents With and Without ASD

Individuals with Autism spectrum disorder (ASD) show altered behavioral synchrony and empathic behavior. Yet, an ecologically valid examination of these in adolescents is still required. We employed a social interaction sequence comprising a friendly conversation with a confederate, an expression of distress by her, and a return to friendly conversation. 44 male adolescents (22 with ASD) participated. Socio-emotional behaviors, coded by blind raters and through automated analyses of motion, were analyzed. Results indicated reduced synchrony in the ASD group. Moreover, whereas controls displayed a decrease in synchrony when facing another's distress, adolescents with ASD showed no such change. No group differences were found on empathic behavior. Findings imply gaps between verbal and non-verbal responses of adolescents with ASD to a distressed interaction partner.

Socializing Sensorimotor Contingencies

The aim of this review is to highlight the idea of grounding social cognition in sensorimotor interactions shared across agents. We discuss an action-oriented account that emerges from a broader interpretation of the concept of sensorimotor contingencies. We suggest that dynamic informational and sensorimotor coupling across agents can mediate the deployment of action-effect contingencies in social contexts. We propose this concept of socializing sensorimotor contingencies (socSMCs) as a shared framework of analysis for processes within and across brains and bodies, and their physical and social environments. In doing so, we integrate insights from different fields, including neuroscience, psychology, and research on human-robot interaction. We review studies on dynamic embodied interaction and highlight empirical findings that suggest an important role of sensorimotor and informational entrainment in social contexts. Furthermore, we discuss links to closely related concepts, such as enactivism, models of coordination dynamics and others, and clarify differences to approaches that focus on mentalizing and high-level cognitive representations. Moreover, we consider conceptual implications of rethinking cognition as social sensorimotor coupling. The insight that social cognitive phenomena like joint attention, mutual trust or empathy rely heavily on the informational and sensorimotor coupling between agents may provide novel remedies for people with disturbed social cognition and for situations of disturbed social interaction. Furthermore, our proposal has potential applications in the field of human-robot interaction where socSMCs principles might lead to more natural and intuitive interfaces for human users.

Eye contact marks the rise and fall of shared attention in conversation

Conversation is the platform where minds meet: the venue where information is shared, ideas cocreated, cultural norms shaped, and social bonds forged. Its frequency and ease belie its complexity. Every conversation weaves a unique shared narrative from the contributions of independent minds, requiring partners to flexibly move into and out of alignment as needed for conversation to both cohere and evolve. How two minds achieve this coordination is poorly understood. Here we test whether eye contact, a common feature of conversation, predicts this coordination by measuring dyadic pupillary synchrony (a corollary of shared attention) during natural conversation. We find that eye contact is positively correlated with synchrony as well as ratings of engagement by conversation partners. However, rather than elicit synchrony, eye contact commences as synchrony peaks and predicts its immediate and subsequent decline until eye contact breaks. This relationship suggests that eye contact signals when shared attention is high. Furthermore, we speculate that eye contact may play a corrective role in disrupting shared attention (reducing synchrony) as needed to facilitate independent contributions to conversation.

The Potential Role of Dopamine in Mediating Motor Function and Interpersonal Synchrony

Motor functions in general and motor planning in particular are crucial for our ability to synchronize our movements with those of others. To date, these co-occurring functions have been studied separately, and as yet it is unclear whether they share a common biological mechanism. Here, we synthesize disparate recent findings on motor functioning and interpersonal synchrony and propose that these two functions share a common neurobiological mechanism and adhere to the same principles of predictive coding. Critically, we describe the pivotal role of the dopaminergic system in modulating these two distinct functions. We present attention deficit hyperactivity disorder (ADHD) as an example of a disorder that involves the dopaminergic system and describe deficits in motor and interpersonal synchrony. Finally, we suggest possible directions for future studies emphasizing the role of dopamine modulation as a link between social and motor functioning.

Movement and Emotional Facial Expressions during the Adult Attachment Interview: Interaction Effects of Attachment and Anxiety Disorder

INTRODUCTION

Adult attachment is commonly associated with emotion regulation. Less is known about the nonverbal embodiment of adult attachment.

OBJECTIVE

We hypothesized that dismissing attachment is related to less movement and fewer facial expressions of emotions, whereas preoccupied attachment is associated with more negative emotional facial expressions. Moreover, the interaction of attachment and the presence of an anxiety disorder (AD) was explored.

METHODS

The sample included 95 individuals, 21 with AD without comorbidity, 21 with AD and comorbid major depression (AD-CD), and 53 healthy controls. We analyzed nonverbal behavior during a part of the Adult Attachment Interview (AAI) asking about the family and parental figures. The movements of the interviewees were captured via Motion Energy Analysis. Facial expressions were coded according to the Facial Action Coding System using the OpenFace software. We compared individuals with secure, dismissing, and preoccupied states of mind (assessed with the AAI) with regard to the frequency and complexity of movements and the frequency of the facial expressions such as happy, sad, and contemptuous.

RESULTS

As expected, dismissingly attached individuals moved less often and with lower complexity than securely attached. For emotional facial expressions, a main effect of the disorder group and interaction effects of attachment by disorder were found. In the AD-CD group, dismissingly attached patients showed comparatively fewer happy facial expressions than securely attached individuals.

CONCLUSIONS

Reduced movement specifically seems to be related to dismissing attachment when interviewees talk about significant parental figures. Facial expressions of emotions related to attachment occurred when maladaptive emotion regulation strategies were intensified by a psychological disorder.

An Embodied Artistic Inquiry into Attachment-Oriented Therapeutic Relationships

In this study, I utilized an embodied artistic inquiry self-study to explore my experience of attachment in the therapeutic movement relationships (TMR) created as a dance/movement therapy intern at a psychiatric residential treatment center for children. The research was guided by three questions: How do I experience the TMR with children in a psychiatric residential treatment setting using attachment theory? How is my personal attachment style influencing and guiding the therapeutic relationship? How does my identification of salient moments relate to my own attachment style and aesthetic preference? Data were collected using journal entries that reflected on the researcher’s experience of attachment, saliency, and Tortora’s D.A.N.C.E. qualities of attachment (Clin Soc Work J 38(1):37–50, https://doi.org/10.1007/s10615-009-0254-9, 2010). I analyzed the data using discussion and Authentic Movement with a research consultant in order to synthesize and describe the experience of each salient moment. Repeated movements included grounded and unstable walking, changing of levels, core-distal movements, circling and carving arms, and recuperation. The themes that resulted from repeated movements and discussion with the research consultant include foundational movements, holding discomfort, connection to a specific client, and playfulness. These results reinforced the importance of stability and self-awareness for a therapist especially in relationship to how their movement and nonverbal preferences may have been learned from attachment relationships. Furthermore, results show the impact of saliency and the clinician’s aesthetic preference. In addition, the results reflected the strong relationship among nonverbal qualities of attachment and the TMR. These results suggested that qualities of attachment underlie the effectiveness of the TMR. Although limitations of the study prevented me from drawing correlative conclusions, the therapist may be able to strengthen the therapeutic relationship by targeting primary attachment models, and suggestions for further research are included.

Herding in human groups is related to high autistic traits

Herding is ubiquitous throughout all social life forms, providing beneficial outcomes. Here, we examine whether herding emerges spontaneously in human groups and whether it adheres to the core principles of herding observed in the animal kingdom. Using a computerized paradigm involving the movements of circles, we tested the emergence of spontaneous and intentional herding of 136 participants assigned into groups of four participants. Herding was assessed by measuring directional synchrony in the movements of the circles, level of cohesion, and separation between circles. We found that human groups tend to spontaneously herd, particularly in terms of directional synchrony, supporting the notion of a human herding instinct. We further asked whether individuals with high traits of Autism Spectrum Disorder (ASD) exhibit differences in their herding tendencies. Results indicated that individuals with high ASD traits showed greater social separation from the group, compared to individuals with low ASD traits. Moreover, we found diminished spontaneous synchrony, but intact instructed synchrony in the high vs. the low ASD traits group. We contend that humans spontaneously herd with their group and suggest that the spontaneous tendency to synchronize with others is diminished in individuals with high ASD traits, though it is recovered when synchronization is intentional.

In and out of synchrony-Behavioral and physiological dynamics of dyadic interpersonal coordination

Interpersonal synchrony, the temporal coordination of actions, emotions, thoughts and physiological processes, is a widely studied ubiquitous phenomenon. Research has already established that more synchrony is not always more beneficial, especially in the fields of emotional and physiological synchrony. Despite this fact, the dominant tone in the literature is that behavioral interpersonal synchrony is a pro-social phenomenon, and hence, in social contexts, more behavioral synchrony is generally considered better. In accordance with that tone, the naturally occurring dynamics of moving in and out of synchrony have rarely been studied or considered as an adaptive state. In the present article, we aim to present a new model of interpersonal synchrony, based on the existing literature assessing synchrony as well as the ideas of complex dynamical systems. At the core of our model is the idea that two tendencies exist simultaneously, one to synchronize with others and another to move out of synchrony and act independently. We suggest that an adaptive interpersonal system is a flexible one, able to continuously adjust itself to the social context. We suggest that the concept of meta-stability might be a marker of such a flexible interpersonal system. Moreover, the model considers both behavioral and physiological aspects in order to provide a more extensive account. We present research implications of the model, as well as a demonstration of the model's applicability to data, and provide code researchers can use to analyze their own data in these methods. Finally, we discuss future directions in detail.

How to be a secure base: therapists' attachment representations and their link to attunement in psychotherapy

This paper investigates if therapists' attachment classifications are linked to different types of therapists' attunement in session. We present coding procedures and validation of the Therapist Attunement Scales (TASc), a transcript-based instrument that assesses attunement in therapy and that we hypothesized would be associated with therapists' attachment classifications. Fifty therapists were administered the Adult Attachment Interview (AAI), and therapy sessions with each therapist were rated with the TASc. Therapists also completed the WAI-T to assess the therapeutic alliance and divergent validity of the TASc. Results indicate strong inter-rater reliability and stability across consecutive sessions of the TASc, as well as high convergent validity between one session rated with the TASc and the AAI rated independently (κ = .81). No significant associations were found with the WAI-T, which offers preliminary evidence of divergent validity of the TASc. These results suggest that therapists of different attachment classifications may attune to patients in distinct ways. These results also present the TASc as a valid measure of therapists' attachment in psychotherapy and as a promising tool for training and supervision.

The Body Speaks: Using the Mirror Game to Link Attachment and Non-verbal Behavior

The Mirror Game (MG) is a common exercise in dance/movement therapy and drama therapy. It is used to promote participants' ability to enter and remain in a state of togetherness. In spite of the wide use of the MG by practitioners, it is only recently that scientists begun to use the MG in research, examining its correlates, validity, and reliability. This study joins this effort by reporting on the identification of scale items to describe the non-verbal behavior expressed during the MG and its correlation to measures of attachment. Thus, we explored the application of the MG as a tool for assessing the embodiment of attachment in adulthood. Forty-eight participants (22 females, mean age = 33.2) played the MG with the same gender-matched expert players. All MG were videotaped. In addition, participants were evaluated on two central measurements of attachment in adulthood: The Adult Attachment Interview (AAI) and the Experience in Close Relationship questionnaire (ECR). To analyze the data, we developed the "MG scale" that coded the non-verbal behavior during the movement interaction, using 19 parameters. The sub-scales were reduced using factor analysis into two dimensions referred to as "together" and "free." The free factor was significantly correlated to both measurements of attachment: Participants classified as having secure attachment on the AAI, received higher scores on the MG free factor than participants classified as insecure [t(46) = 7.858, p = 0.000]. Participants, who were high on the avoidance dimension on the ECR, were low on the MG free factor [r(48) = -0.285, p = 0.007]. This is the first study to examine the MG as it is used by practitioners and its correlation to highly standardized measures. This exploratory study may be considered as part of the first steps of exploring the MG as a standardized assessment tool. The advantages of the MG as a simple, non-verbal movement interaction demonstrate some of the strengths of dance/movement and drama therapy practice.

Dramatic action: A theater-based paradigm for analyzing human interactions

Existing approaches to describe social interactions consider emotional states or use ad-hoc descriptors for microanalysis of interactions. Such descriptors are different in each context thereby limiting comparisons, and can also mix facets of meaning such as emotional states, short term tactics and long-term goals. To develop a systematic set of concepts for second-by-second social interactions, we suggest a complementary approach based on practices employed in theater. Theater uses the concept of dramatic action, the effort that one makes to change the psychological state of another. Unlike states (e.g. emotions), dramatic actions aim to change states; unlike long-term goals or motivations, dramatic actions can last seconds. We defined a set of 22 basic dramatic action verbs using a lexical approach, such as ‘to threaten’–the effort to incite fear, and ‘to encourage’–the effort to inspire hope or confidence. We developed a set of visual cartoon stimuli for these basic dramatic actions, and find that people can reliably and reproducibly assign dramatic action verbs to these stimuli. We show that each dramatic action can be carried out with different emotions, indicating that the two constructs are distinct. We characterized a principal valence axis of dramatic actions. Finally, we re-analyzed three widely-used interaction coding systems in terms of dramatic actions, to suggest that dramatic actions might serve as a common vocabulary across research contexts. This study thus operationalizes and tests dramatic action as a potentially useful concept for research on social interaction, and in particular on influence tactics.

Coordinated Interpersonal Behaviour in Collective Dance Improvisation: The Aesthetics of Kinaesthetic Togetherness

Collective dance improvisation (e.g., traditional and social dancing, contact improvisation) is a participatory, relational and embodied art form which eschews standard concepts in aesthetics. We present our ongoing research into the mechanisms underlying the lived experience of “togetherness” associated with such practices. Togetherness in collective dance improvisation is kinaesthetic (based on movement and its perception), and so can be simultaneously addressed from the perspective of the performers and the spectators, and be measured. We utilise these multiple levels of description: the first-person, phenomenological level of personal experiences, the third-person description of brain and body activity, and the level of interpersonal dynamics. Here, we describe two of our protocols: a four-person mirror game and a ‘rhythm battle’ dance improvisation score. Using an interpersonal closeness measure after the practice, we correlate subjective sense of individual/group connectedness and observed levels of in-group temporal synchronization. We propose that kinaesthetic togetherness, or interpersonal resonance, is integral to the aesthetic pleasure of the participants and spectators, and that embodied feeling of togetherness might play a role more generally in aesthetic experience in the performing arts.

Patterns of Joint Improvisation in Adults with Autism Spectrum Disorder

Recent research on autism spectrum disorders (ASDs) suggests that individuals with autism may have a basic deficit in synchronizing with others, and that this difficulty may lead to more complex social and communicative deficits. Here, we examined synchronization during an open-ended joint improvisation (JI) paradigm, called the mirror game (MG). In the MG, two players take turns leading, following, and jointly improvising motion using two handles set on parallel tracks, while their motion tracks are recorded with high temporal and spatial resolution. A series of previous studies have shown that players in the MG attain moments of highly synchronized co-confident (CC) motion, in which there is no typical kinematic pattern of leader and reactive follower. It has been suggested that during these moments players act as a coupled unit and feel high levels of connectedness. Here, we aimed to assess whether participants with ASD are capable of attaining CC, and whether their MG performance relates to broader motor and social skills. We found that participants with ASD (n = 34) can indeed attain CC moments when playing with an expert improviser, though their performance was attenuated in several ways, compared to typically developing (TD) participants (n = 35). Specifically, ASD participants had lower rates of CC, compared with TD participants, which was most pronounced during the following rounds. In addition, the duration of their CC segments was shorter, across all rounds. When controlling for participants' motor skills (both on the MG console, and more broadly) some of the variability in MG performance was explained, but group differences remained. ASD participants' alexithymia further correlated with their difficulty following another's lead; though other social skills did not relate to MG performance. Participants' subjective reports of the game suggest that other cognitive and emotional factors, such as attention, motivation, and reward-processing, which were not directly measured in the experiment, may impact their performance. Together, these results show that ASD participants can attain moments of high motor synchronization with an expert improviser, even during an open-ended task. Future studies should examine the ways in which these skills may be further harnessed in clinical settings.

Synchrony in Joint Action Is Directed by Each Participant's Motor Control System

In this work, we ask how the probability of achieving synchrony in joint action is affected by the choice of motion parameters of each individual. We use the mirror game paradigm to study how changes in leader's motion parameters, specifically frequency and peak velocity, affect the probability of entering the state of co-confidence (CC) motion: a dyadic state of synchronized, smooth and co-predictive motions. In order to systematically study this question, we used a one-person version of the mirror game, where the participant mirrored piece-wise rhythmic movements produced by a computer on a graphics tablet. We systematically varied the frequency and peak velocity of the movements to determine how these parameters affect the likelihood of synchronized joint action. To assess synchrony in the mirror game we used the previously developed marker of co-confident (CC) motions: smooth, jitter-less and synchronized motions indicative of co-predicative control. We found that when mirroring movements with low frequencies (i.e., long duration movements), the participants never showed CC, and as the frequency of the stimuli increased, the probability of observing CC also increased. This finding is discussed in the framework of motor control studies showing an upper limit on the duration of smooth motion. We confirmed the relationship between motion parameters and the probability to perform CC with three sets of data of open-ended two-player mirror games. These findings demonstrate that when performing movements together, there are optimal movement frequencies to use in order to maximize the possibility of entering a state of synchronized joint action. It also shows that the ability to perform synchronized joint action is constrained by the properties of our motor control systems.

Design of a Virtual Player for Joint Improvisation with Humans in the Mirror Game

Joint improvisation is often observed among humans performing joint action tasks. Exploring the underlying cognitive and neural mechanisms behind the emergence of joint improvisation is an open research challenge. This paper investigates jointly improvised movements between two participants in the mirror game, a paradigmatic joint task example. First, experiments involving movement coordination of different dyads of human players are performed in order to build a human benchmark. No designation of leader and follower is given beforehand. We find that joint improvisation is characterized by the lack of a leader and high levels of movement synchronization. Then, a theoretical model is proposed to capture some features of their interaction, and a set of experiments is carried out to test and validate the model ability to reproduce the experimental observations. Furthermore, the model is used to drive a computer avatar able to successfully improvise joint motion with a human participant in real time. Finally, a convergence analysis of the proposed model is carried out to confirm its ability to reproduce joint movements between the participants.