Prosocial Consequences of Interpersonal Synchrony: A Meta-Analysis

Client-counselor behavioral and inter-brain synchronization among dismissing and secure clients and its association with alliance quality and outcome

Objective This study aimed to explore whether behavioral synchrony (BS) and inter-brain synchrony (IBS) could serve as potential biomarkers for alliance quality or outcomes among clients with different adult attachment styles. Method: We assessed the clients' self-report working alliance and clinical outcomes as well as simultaneously measured BS using motion energy analysis (MEA) and IBS with functional near-infrared spectroscopy (fNIRS) among 37 secure (N = 21) or dismissing (N = 16) clients with their counselors during the first psychological counseling meeting. Results: Dismissing dyads manifested significantly higher late-stage counselor-led and client-led IBS (p = .018) than secure dyads. Adult attachment style served as the moderators in the correlation of both whole-stage client-led BS with bond dimension of alliance (p = .015) as well as in the correlation of both whole-stage no-lag IBS with CORE-10 score changes (p = .022). Moreover, increases in the whole-stage client-led BS were significantly associated with decreases in early-stage, late-stage and whole-stage no-lag IBS (all ps ≤ 0.01). Conclusion: These findings revealed the potentially impeding role of interpersonal synchrony in alliance quality for dismissing clients, at least during the first psychological counseling meetings. They also might partially validate the relationship between different modalities of interpersonal synchrony.

Sexual Synchrony During Partnered Sex

There is growing interest in understanding how sexual arousal unfolds between partners, and how this may change over the course of a relationship and in the face of sexual distress. To capture the variable, dynamic, and dyadic nature of sexual responding, this paper introduces the concept of sexual synchrony, defined as the temporal, reciprocal, and coordinated interchange between partners' subjective and genital sexual arousal. Sexual synchrony is a key mechanism for understanding how partners experience and adapt their sexual arousal responses as they evolve over time. Its relevance lies in examining the mechanisms that may disrupt and facilitate synchrony and exploring how it may contribute to sexual well-being by enabling partners to mutually regulate their sexual arousal within and across sexual interactions. The paper also discusses how sexual synchrony may evolve throughout relationship development and its potential role in sexual problems, offering valuable insights into improving sexual relationships. Suggestions are provided for future research, together with a discussion of the methodological and statistical issues involved when examining sexual dynamics. Understanding how partners jointly regulate their sexual responses allows the development of dyadic models of sexual arousal which will inform treatments for improving couples' (sexual) well-being. The study of sexual synchrony also exemplifies the importance of translational research that is relevant across disciplinary borders.

Mutual gaze and movement synchrony boost observers' enjoyment and perception of togetherness when watching dance duets

As social beings, we are adept at coordinating our body movements and gaze with others. Often, when coordinating with another person, we orient ourselves to face them, as mutual gaze provides valuable cues pertaining to attention and intentions. Moreover, movement synchrony and mutual gaze are associated with prosocial outcomes, yet the perceptual consequences of these forms of coordination remain poorly understood. Across two experiments, we assessed how movement synchrony and gaze direction influence observers' perceptions of dyads. Observers' behavioural responses indicated that dyads are perceived as more socially connected and are more enjoyable to watch when moving synchronously and facing each other. Neuroimaging results showed modulation of the Action Observation and Theory of Mind networks by movement synchrony and mutual gaze, with more robust brain activity when evaluating togetherness (i.e., active and intentional collaboration) than aesthetic value (i.e., enjoyment). A fuller understanding of the consequences of movement synchrony and mutual gaze from the observer's viewpoint holds important implications for social perception, in terms of how observers intuit social relationships within dyads, and the aesthetic value derived from watching individuals moving in these ways.

The benefit of rhythm-based interventions for individuals with autism spectrum disorder: a systematic review and meta-analysis with random controlled trials

Objective

Individuals with autism spectrum disorder (ASD) exhibit impaired behavior synchronization, which is associated with social deficits. Numerous studies have demonstrated that rhythm-based interventions can effectively mitigate social deficits by promoting behavioral synchronization in individuals with ASD. Therefore, a review of the current literature is warranted in this field. The objectives of this review were to explore the effects of rhythm-based interventions on overall social skills and to study the differences in the effects of rhythm-based interventions on specific social skills.

Method

The databases PubMed, Web of Science, Scopus, and Psycinfo were systematically explored until March 2024. A total of eleven research studies, encompassing 408 participants diagnosed with ASD, were incorporated into the meta-analysis. Effect sizes (Hedges' g) were computed for each comparison and amalgamated using random-effects models to evaluate the social skills of individuals with ASD. The methodological quality of each study was evaluated using the Physiotherapy Evidence Database scale(PEDro).

Results

Overall, some valuable observations were made. Rhythm-based interventions had a medium effect on the overall social skills for ASD (Hedges's=0.681; 95%CI[0.075 to 1.286], P  < 0.05). Regarding domain-specific social skills, rhythm-based interventions had a large effect on social interaction (g = 1.299,95% CI [0.508 to 2.091]), a small effect on communication (g = 0.383, 95% CI [0.033 to 0.733], P  < 0.05), and a large effect on emotion (g = 1.752, 95% CI [0.294 to 3.210], P  < 0.05). However, we found a favorable but non-significant effect (g = 0.125, 95% CI [-0.039 to 0.289], P  >  0.05) of rhythm-based interventions on empathy. All study qualities were high (score≥6) using the Physiotherapy Evidence Database (PEDro) scale assessment.

Conclusion

This result indicates the importance of rhythm in the clinical rehabilitation of individuals with ASD. We suggest adding appropriate rhythmic elements to clinical interventions, particularly for individuals with ASD who are less socially competent.

United agency in joint action: A survey study of its prevalence, facilitating factors, and social and emotional effects

United agency refers to a sense of 'acting as one' that sometimes occurs when people engage in joint actions such as group music-making, dancing, and team sports. First-hand accounts of united agency have been reported in a variety of settings, but there exists little systematic evidence regarding when and why the sense of united agency arises. The current study addressed this gap using an online survey in which participants reported general information about their experiences of united agency as well as detailed descriptions of a single memorable experience. Most participants reported experiencing united agency at least occasionally, and those scoring higher on extraversion, agreeableness, and cognitive empathy experienced it more frequently. Memorable experiences of united agency were reported more often in joint actions characterized by synchronous or highly rhythmic coordination, salient shared goals, close or long-term relationships among co-performers, and small to medium group sizes. United agency was often accompanied by positive affect, feelings of alignment and social connection with co-performers, a sense of empowerment, and heightened attention. Together, these findings elucidate the individual characteristics and joint action features that facilitate united agency, shed light on its positive social and emotional consequences, and suggest important avenues for further work investigating its underlying mechanisms.

Benefits of an online group dance program for adolescents' social bonding and wellbeing

INTRODUCTION

The Covid-19 pandemic and its ensuing effects on mental health made it clearer than ever that social bonds are critical for survival, flourishing, and mental wellbeing. Experimental laboratory-based research with children and adults shows that activities involving movement alignment and joint action, such as dance, can facilitate social bonds.

METHODS

This study examined whether an online group dance intervention positively affects social bonding and wellbeing using a randomized control design. Participants were 58 UK adolescents aged 11-16 years (N = 52 girls, 75% White, 7% Asian/Asian British, 18% Mixed-Other), randomly assigned to an online intervention or waitlist control group. Participants in the intervention group completed an online 5-week hip-hop dance program during the Covid-19 pandemic in January to February 2021. Measures of social bonding, wellbeing, and future orientation were taken at the beginning and end of the program.

RESULTS

Linear mixed model analyses examining group × timepoint interaction showed greater increase in social bonding (p < .0001), and wellbeing (p < .0001) in the intervention vs control group. Moreover, increases in bonding significantly predicted increases in wellbeing (p < .0001), and increases in bonding (p = .03) and wellbeing (p = .0002) significantly predicted increases in the adolescents' hope for the future.

CONCLUSIONS

These data, collected at a time of mass social isolation, show that a 5-week-long online dance activity can help adolescents forge stronger social bonds, and improve their wellbeing and future orientation. Our findings suggest that the wellbeing and future orientation benefits of group dance may stem from having stronger social connectedness, opening up avenues for future research and interventions.

Using Wearables to Study Biopsychosocial Dynamics in Couples Who Cope With a Chronic Health Condition: Ambulatory Assessment Study

BACKGROUND

Technology has become an integral part of our everyday life, and its use to manage and study health is no exception. Romantic partners play a critical role in managing chronic health conditions as they tend to be a primary source of support.

OBJECTIVE

This study tests the feasibility of using commercial wearables to monitor couples' unique way of communicating and supporting each other and documents the physiological correlates of interpersonal dynamics (ie, heart rate linkage).

METHODS

We analyzed 617 audio recordings of 5-minute duration (384 with concurrent heart rate data) and 527 brief self-reports collected from 11 couples in which 1 partner had type II diabetes during the course of their typical daily lives. Audio data were coded by trained raters for social support. The extent to which heart rate fluctuations were linked among couples was quantified using cross-correlations. Random-intercept multilevel models explored whether cross-correlations might differ by social contexts and exchanges.

RESULTS

Sixty percent of audio recordings captured speech between partners and partners reported personal contact with each other in 75% of self-reports. Based on the coding, social support was found in 6% of recordings, whereas at least 1 partner self-reported social support about half the time (53%). Couples, on average, showed small to moderate interconnections in their heart rate fluctuations (r=0.04-0.22). Couples also varied in the extent to which there was lagged linkage, that is, meaning that changes in one partner's heart rate tended to precede changes in the other partner's heart rate. Exploratory analyses showed that heart rate linkage was stronger (1) in rater-coded partner conversations (vs moments of no rater-coded partner conversations: rdiff=0.13; P=.03), (2) when partners self-reported interpersonal contact (vs moments of no self-reported interpersonal contact: rdiff=0.20; P<.001), and (3) when partners self-reported social support exchanges (vs moments of no self-reported social support exchange: rdiff=0.15; P=.004).

CONCLUSIONS

Our study provides initial evidence for the utility of using wearables to collect biopsychosocial data in couples managing a chronic health condition in daily life. Specifically, heart rate linkage might play a role in fostering chronic disease management as a couple. Insights from collecting such data could inform future technology interventions to promote healthy lifestyle engagement and adaptive chronic disease management.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR2-10.2196/13685.

Haptic coordination: Squeezing a vibrating stress ball decreases anxiety and arousal

We evaluated the effect of haptic coordination on anxiety and arousal. Participants looked at a stressful or calming image and then repeatedly squeezed a vibrating stress ball for 20 s. Using a pre-post paradigm with a control group, we showed that squeezing the vibrating ball reduced anxiety and arousal, as assessed by the State-Trait Anxiety Inventory and electrodermal activity, respectively. The stability of haptic coordination was manipulated by varying the detuning between the spontaneous squeezing frequency and the intrinsic frequency of ball vibration. Coordination stability affected arousal and stress affected stability. The data were discussed in the light of Kahneman's attentional resource-sharing model.

A framework for joint music making: Behavioral findings, neural processes, and computational models

Across different epochs and societies, humans occasionally gather to jointly make music. This universal form of collective behavior is as fascinating as it is fragmentedly understood. As the interest in joint music making (JMM) rapidly grows, we review the state-of-the-art of this emerging science, blending behavioral, neural, and computational contributions. We present a conceptual framework synthesizing research on JMM within four components. The framework is centered upon interpersonal coordination, a crucial requirement for JMM. The other components imply the influence of individuals' (past) experience, (current) social factors, and (future) goals on real-time coordination. Our aim is to promote the development of JMM research by organizing existing work, inspiring new questions, and fostering accessibility for researchers belonging to other research communities.

Mirror game as a tool to influence interpersonal spontaneous behavior after performance

Mirror game (MG) is an exercise in which participants imitate each other. Our study explored its spontaneous behavioral consequences after performance. In a baseline (BL) phase, two participants performed a joint Simon task. Then, they performed a lure task during which we measured the interpersonal distance they spontaneously adopted. The BL phase was followed by two phases (in counterbalanced order). The MG phase started with a MG, before a procedure like the BL phase. The individual movement (IM) phase started with movements performed alone before a procedure like the BL phase. Interpersonal distance analysis suggested that MG enhanced spontaneous approach toward the partner, whereas IM induced spontaneous avoidance. Moreover, the joint Simon effect (JSE) tended to be smaller after IM, suggesting a decreasing inclination to integrate the partner's response in one's own action plan. Furthermore, in IM phase, JSE decreased as interpersonal distance increased.

Prospects for Augmenting Team Interactions with Real-Time Coordination-Based Measures in Human-Autonomy Teams

Complex work in teams requires coordination across team members and their technology as well as the ability to change and adapt over time to achieve effective performance. To support such complex interactions, recent efforts have worked toward the design of adaptive human-autonomy teaming systems that can provide feedback in or near real time to achieve the desired individual or team results. However, while significant advancements have been made to better model and understand the dynamics of team interaction and its relationship with task performance, appropriate measures of team coordination and computational methods to detect changes in coordination have not yet been widely investigated. Having the capacity to measure coordination in real time is quite promising as it provides the opportunity to provide adaptive feedback that may influence and regulate teams' coordination patterns and, ultimately, drive effective team performance. A critical requirement to reach this potential is having the theoretical and empirical foundation from which to do so. Therefore, the first goal of the paper is to review approaches to coordination dynamics, identify current research gaps, and draw insights from other areas, such as social interaction, relationship science, and psychotherapy. The second goal is to collate extant work on feedback and advance ideas for adaptive feedback systems that have potential to influence coordination in a way that can enhance the effectiveness of team interactions. In addressing these two goals, this work lays the foundation as well as plans for the future of human-autonomy teams that augment team interactions using coordination-based measures.

Dyadic body competence predicts movement synchrony during the mirror game

The process of synchronizing our body movements with others is known to enhance rapport, affect, and prosociality. Furthermore, emerging evidence suggests that synchronizing activities may enhance cognitive performance. Unknown, by contrast, is the extent to which people's individual traits and experiences influence their ability to achieve and maintain movement synchrony with another person, which is key for unlocking the social and affective benefits of movement synchrony. Here, we take a dyad-centered approach to gain a deeper understanding of the role of embodiment in achieving and maintaining movement synchrony. Using existing data, we explored the relationship between body competence and body perception scores at the level of the dyad, and the dyad's movement synchrony and complexity while playing a 2.5-min movement mirroring game. The data revealed that dyadic body competence scores positively correlate with movement synchrony, but not complexity, and that dyadic body perception scores are not associated with movement synchrony or complexity. Movement synchrony was greater when the more experienced member of the dyad was responsible for copying movements. Finally, movement synchrony and complexity were stable across the duration of the mirror game. These findings show that movement synchrony is sensitive to the composition of the dyad involved, specifically the dyad's embodiment, illuminating the value of dyadic approaches to understanding body movements in social contexts.

More Than Just Movement: Exploring Embodied Group Synchrony During Seated Dance for Older Adults Living in Residential Aged Care Communities

One in six people in Australia are aged over 65, with many older adults currently living in residential aged care communities (RACC). Fostering meaningful human connection through social activities, such as dance, is imperative to maintain or improve the quality of life in these settings. Drawing from an embodied cognition framework, this mixed-methods study explored synchrony during a seated dance program with 15 older adults living in a RACC. Qualitative video content analysis was used to code movement, language and music cooccurrences, resulting in five group synchrony labels. Hierarchical Cluster Analysis (HCA) was then employed to distil ten higher-order forms of embodied group synchrony. Using existing neurocognitive evidence, we detail the therapeutic and interpersonal implications of the most prominent forms of embodied group synchrony. These findings can be used to choreograph therapeutic forms of embodied group synchrony in dance programs with older adults.

How and Why People Synchronize: An Integrated Perspective

Academic AbstractInterpersonal synchrony, the alignment of behavior and/or physiology during interactions, is a pervasive phenomenon observed in diverse social contexts. Here we synthesize across contexts and behaviors to classify the different forms and functions of synchrony. We provide a concise framework for classifying the manifold forms of synchrony along six dimensions: periodicity, discreteness, spatial similarity, directionality, leader-follower dynamics, and observability. We also distill the various proposed functions of interpersonal synchrony into four interconnected functions: reducing complexity and improving understanding, accomplishing joint tasks, strengthening social connection, and influencing partners' behavior. These functions derive from first principles, emerge from each other, and are accomplished by some forms of synchrony more than others. Effective synchrony flexibly adapts to social goals and more synchrony is not always better. Our synthesis offers a shared framework and language for the field, allowing for better cross-context and cross-behavior comparisons, generating new hypotheses, and highlighting future research directions.

Interpersonal neural synchrony and mental disorders: unlocking potential pathways for clinical interventions

Introduction

Interpersonal synchronization involves the alignment of behavioral, affective, physiological, and brain states during social interactions. It facilitates empathy, emotion regulation, and prosocial commitment. Mental disorders characterized by social interaction dysfunction, such as Autism Spectrum Disorder (ASD), Reactive Attachment Disorder (RAD), and Social Anxiety Disorder (SAD), often exhibit atypical synchronization with others across multiple levels. With the introduction of the "second-person" neuroscience perspective, our understanding of interpersonal neural synchronization (INS) has improved, however, so far, it has hardly impacted the development of novel therapeutic interventions.

Methods

To evaluate the potential of INS-based treatments for mental disorders, we performed two systematic literature searches identifying studies that directly target INS through neurofeedback (12 publications; 9 independent studies) or brain stimulation techniques (7 studies), following PRISMA guidelines. In addition, we narratively review indirect INS manipulations through behavioral, biofeedback, or hormonal interventions. We discuss the potential of such treatments for ASD, RAD, and SAD and using a systematic database search assess the acceptability of neurofeedback (4 studies) and neurostimulation (4 studies) in patients with social dysfunction.

Results

Although behavioral approaches, such as engaging in eye contact or cooperative actions, have been shown to be associated with increased INS, little is known about potential long-term consequences of such interventions. Few proof-of-concept studies have utilized brain stimulation techniques, like transcranial direct current stimulation or INS-based neurofeedback, showing feasibility and preliminary evidence that such interventions can boost behavioral synchrony and social connectedness. Yet, optimal brain stimulation protocols and neurofeedback parameters are still undefined. For ASD, RAD, or SAD, so far no randomized controlled trial has proven the efficacy of direct INS-based intervention techniques, although in general brain stimulation and neurofeedback methods seem to be well accepted in these patient groups.

Discussion

Significant work remains to translate INS-based manipulations into effective treatments for social interaction disorders. Future research should focus on mechanistic insights into INS, technological advancements, and rigorous design standards. Furthermore, it will be key to compare interventions directly targeting INS to those targeting other modalities of synchrony as well as to define optimal target dyads and target synchrony states in clinical interventions.

What Makes Groups Emotional?

When people experience emotions in a group, their emotions tend to have stronger intensity and to last longer. Why is that? This question has occupied thinkers throughout history, and with the use of digital media it is even more pressing today. Historically, attention has mainly focused on processes driven by the way emotions are shared between people via emotional interactions. Although interactions are a major driver of group emotionality, I review empirical findings that suggest that understanding group emotionality requires a broader view that integrates two additional processes: how emotions unfold within the social infrastructure in which they are shared and how these processes are affected by people's cognition about emotions. I propose to summarize the literature using an infrastructure-cognition-interaction framework that contributes to a broader understanding of group emotionality, which should improve our ability to predict group emotionality and to change these emotions when they are undesired.

Interpersonal motor synchrony in autism: a systematic review and meta-analysis

Introduction

Interpersonal motor synchrony (IMS) is the spontaneous, voluntary, or instructed coordination of movements between interacting partners. Throughout the life cycle, it shapes social exchanges and interplays with intra- and inter-individual characteristics that may diverge in Autism Spectrum Disorder (ASD). Here we perform a systematic review and meta-analysis to summarize the extant literature and quantify the evidence about reduced IMS in dyads including at least one participant with a diagnosis of ASD.

Methods

Empirical evidence from sixteen experimental studies was systematically reviewed, encompassing spontaneous and instructed paradigms as well as a paucity of measures used to assess IMS. Of these, thirteen studies (n = 512 dyads) contributed measures of IMS with an in situ neurotypical partner (TD) for ASD and control groups, which could be used for meta-analyses.

Results

Reduced synchronization in ASD-TD dyads emerged from both the systematic review and meta-analyses, although both small and large effect sizes (i.e., Hedge's g) in favor of the control group are consistent with the data (Hedge's g = .85, p < 0.001, 95% CI[.35, 1.35], 95% PI[-.89, 2.60]).

Discussion

Uncertainty is discussed relative to the type of task, measures, and age range considered in each study. We further discuss that sharing similar experiences of the world might help to synchronize with one another. Future studies should not only assess whether reduced IMS is consistently observed in ASD-TD dyads and how this shapes social exchanges, but also explore whether and how ASD-ASD dyads synchronize during interpersonal exchanges.

Love songs and serenades: a theoretical review of music and romantic relationships

In this theoretical review, we examine how the roles of music in mate choice and social bonding are expressed in romantic relationships. Darwin's Descent of Man originally proposed the idea that musicality might have evolved as a sexually selected trait. This proposition, coupled with the portrayal of popular musicians as sex symbols and the prevalence of love-themed lyrics in music, suggests a possible link between music and attraction. However, recent scientific exploration of the evolutionary functions of music has predominantly focused on theories of social bonding and group signaling, with limited research addressing the sexual selection hypothesis. We identify two distinct types of music-making for these different functions: music for attraction, which would be virtuosic in nature to display physical and cognitive fitness to potential mates; and music for connection, which would facilitate synchrony between partners and likely engage the same reward mechanisms seen in the general synchrony-bonding effect, enhancing perceived interpersonal intimacy as a facet of love. Linking these two musical functions to social psychological theories of relationship development and the components of love, we present a model that outlines the potential roles of music in romantic relationships, from initial attraction to ongoing relationship maintenance. In addition to synthesizing the existing literature, our model serves as a roadmap for empirical research aimed at rigorously investigating the possible functions of music for romantic relationships.

An observation of a negative effect of social cohesion on creativity in musical improvisation

Although various social factors can significantly impact creative performance, it is still unclear how social cohesion (i.e., how close we feel to others) influences creativity. We therefore conducted two studies exploring the association between social cohesion and creativity within the domain of musical improvisation, a prime example of creative performance, which usually plays out in social contexts. The first study (n = 58 musical novices) showed that music-induced synchrony facilitates social cohesion. In our second study (n = 18 musical novices), we found that in two out of three experimental conditions, increased social cohesion is associated with less creative musical outcomes, as rated by nine expert musicians. In our subsequent analysis we related measures of social cohesion and creativity. This approach highlights how, within a musical setting, creativity unfolds in the context of social contingencies as social cohesion and related factors.

Evaluations of dyadic synchrony: observers' traits influence estimation and enjoyment of synchrony in mirror-game movements

While evidence abounds that motor synchrony is a powerful form of 'social glue' for those involved, we have yet to understand how observers perceive motor synchrony: can observers estimate the degree of synchrony accurately? Is synchrony aesthetically pleasing? In two preregistered experiments (n = 161 each), we assess how accurately observers can estimate the degree of synchrony in dyads playing the mirror game, and how much observers enjoy watching these movements. We further assess whether accuracy and enjoyment are influenced by individual differences in self-reported embodied expertise (ability to reproduce movements, body awareness, body competence), psychosocial resources (extraversion, self-esteem), or social competencies (empathy, autistic traits), while objectively controlling for the degree of measured synchrony and complexity. The data revealed that observers' estimated synchrony with poor accuracy, showing a tendency to underestimate the level of synchrony. Accuracy for low synchrony improved with increasing body competence, while accuracy for high synchrony improved with increasing autistic traits. Observers' enjoyment of dyadic movements correlated positively with the degree of measured synchrony, the predictability of the movements, and the observer's empathy. Furthermore, very low enjoyment was associated with increased body perception. Our findings indicate that accuracy in perceiving synchrony is closely linked to embodiment, while aesthetic evaluations of action hinge on individual differences.

How self-disclosure of negative experiences shapes prosociality?

People frequently share their negative experiences and feelings with others. Little is known, however, about the social outcomes of sharing negative experiences and the underlying neural mechanisms. We addressed this dearth of knowledge by leveraging functional near-infrared spectroscopy (fNIRS) hyperscanning: while dyad participants took turns to share their own (self-disclosure group) or a stranger's (non-disclosure group) negative and neutral experiences, their respective brain activity was recorded simultaneously by fNIRS. We observed that sharing negative (relative to neutral) experiences enhanced greater mutual prosociality, emotional empathy and interpersonal neural synchronization (INS) at the left superior frontal cortex in the self-disclosure group compared to the non-disclosure group. Importantly, mediation analyses further revealed that in the self-disclosure (but not non-disclosure) group, the increased emotional empathy and INS elicited by sharing negative experiences relative to sharing neutral experiences promoted the enhanced prosociality through increasing interpersonal liking. These results indicate that self-disclosure of negative experiences can promote prosocial behaviors via social dynamics (defined as social affective and cognitive factors, including empathy and liking) and shared neural responses. Our findings suggest that when people express negative sentiments, they incline to follow up with positive actions.

Spontaneous bodily coordination varies across affective and intellectual child-adult interactions

Research on child-adult interactions has identified that the morphology of bodily coordination seems to be sensitive to age and type of interaction. Mirror-like imitation emerges earlier in life and is more common during emotionally laden interactions, while anatomical imitation is acquired later and associated with cognitive tasks. However, it remains unclear whether these morphologies also vary with age and type of interaction during spontaneous coordination. Here we report a motion capture study comparing the spontaneous coordination patterns of thirty-five 3-year-old (20 girls; Mage = 3.15 years) and forty 6-year-old children (20 girls; Mage = 6.13 years) interacting with unacquainted adults during two storytelling sessions. The stories narrated the search of a character for her mother (Predominantly Affective Condition) or an object (Predominantly Intellectual Condition) inside a supermarket. Results show that children of both ages consistently coordinated their spontaneous movements towards adult storytellers, both in symmetric and asymmetric ways. However, symmetric coordination was more prominent in 3-year-old children and during predominantly emotional interactions, whereas asymmetric coordination prevailed in 6-year-old children and during predominantly intellectual interactions. These results add evidence from spontaneous interactions in favor of the hypothesis that symmetric coordination is associated with affective interactions and asymmetric coordination with intellectual ones.

Biological principles for music and mental health

Efforts to integrate music into healthcare systems and wellness practices are accelerating but the biological foundations supporting these initiatives remain underappreciated. As a result, music-based interventions are often sidelined in medicine. Here, I bring together advances in music research from neuroscience, psychology, and psychiatry to bridge music's specific foundations in human biology with its specific therapeutic applications. The framework I propose organizes the neurophysiological effects of music around four core elements of human musicality: tonality, rhythm, reward, and sociality. For each, I review key concepts, biological bases, and evidence of clinical benefits. Within this framework, I outline a strategy to increase music's impact on health based on standardizing treatments and their alignment with individual differences in responsivity to these musical elements. I propose that an integrated biological understanding of human musicality-describing each element's functional origins, development, phylogeny, and neural bases-is critical to advancing rational applications of music in mental health and wellness.

Why We Gather: A New Look, Empirically Documented, at Émile Durkheim's Theory of Collective Assemblies and Collective Effervescence

For Durkheim, individuals' survival and well-being rest on cultural resources and social belonging that must be revived periodically in collective assemblies. Durkheim's concern was to clarify how these assemblies achieve this revitalization. An intensive examination of primitive religions led him to identify successive levels of engagement experienced by participants and to develop explanatory principles relevant to all types of collective gatherings. Durkheim's conception is widely referred to nowadays. However, the question of its empirical status remains open. We extracted from his text his main statements and translated them into research questions. We then examined each question in relation to current theories and findings. In particular, we relied on the plethora of recent cognitive and social-psychology studies that document conditions of reduced self-other differentiation. Abundant data support that each successive moment of collective assemblies contributes to blurring this differentiation. Ample support also exists that because shared emotions are increasingly amplified in collective context, they can fuel high-intensity experiences. Moreover, recent studies of self-transcendent emotions can account for the self-transformative effects described by Durkheim at the climax of collective assemblies. In conclusion, this century-old model is remarkably supported by recent results, mostly collected in experimental settings.

The Synchrony-Prosociality Link Cannot Be Explained Away as Expectancy Effect: Response to Atwood et al. ()

Moving in time to others, as is often observed in dance, music, sports and much of children's play cross-culturally, is thought to make people feel and act more prosocially towards each other. In a recent paper, Atwood et al. (2022) argued that the inferential validity of this link found between synchronous behaviour and prosociality might be mainly due to "expectancy effects generated by a combination of (1) experimenter expectancy, leading to experimenter bias; and (2) participant expectancy (i.e., placebo effects)". Here, we counter these arguments with (1) examples of studies devoid of experimenter expectancy effects that nevertheless demonstrate a positive link between synchrony and prosociality, and (2) insights from the developmental literature that address participant expectancy by showing how expectations formed through lived experiences of synchronous interactions do not necessarily threaten inferential validity. In conclusion, there is already sufficient good-quality evidence showing the positive effects of synchronous behaviours on prosociality beyond what can be explained by experimenter or participant expectation effects.

Beyond simultaneity: Temporal interdependence of behavior is key to affiliative effects of interpersonal synchrony in children

Interpersonal synchrony (IPS) is the temporal coordination of behavior during social interactions. IPS acts as a social cue signifying affiliation both when children witness IPS between others and when they experience it themselves. However, it is unclear which temporal qualities of IPS produce these effects and why. We hypothesized that both the simultaneity and temporal regularity of partners' actions would influence affiliation judgments and that subjective perceptions of IPS ("togetherness") would play a role in mediating these relations. In two online tasks, children aged 4 to 11 years listened to a pair of children tapping (witnessed IPS; n = 68) or themselves tapped with another child (experienced IPS; n = 63). Tapping partners were presented as real, but the sounds attributed to them were computer generated so that their temporal relations could be experimentally manipulated. The simultaneity and regularity of their tapping was systematically manipulated across trials. For witnessed IPS, both the simultaneity and regularity of partners' tapping significantly positively affected the perceived degree of affiliation between them. These effects were mediated by the perceived togetherness of the tapping. No affiliative effects of IPS were found in the experienced IPS condition. Our findings suggest that both the simultaneity and regularity of partners' actions influence children's affiliation judgments when witnessing IPS via elicited perceptions of togetherness. We conclude that temporal interdependence-which includes but is not limited to simultaneity of action-is responsible for inducing perceptions of affiliation during witnessed IPS.

Using a haptic dynamic clamp to reduce arousal: preference, arousal, and coordination stability are related

We have developed a haptic dynamic clamp dedicated to the regulation of arousal. It takes the form of a vibrating stress ball to be squeezed, called Viball, controlled by Righetti's nonlinear adaptive Hopf oscillator. Participants squeezed an adaptive Viball which adapts its frequency of vibration to the current frequency of human squeezing. The adaptive Viball was compared to three non-adaptive Viballs, parametrized to vibrate at a lower, equal, or higher frequency than the participants' preferred frequency. While squeezing the ball, participants looked at stressful or calming pictures and their electrodermal activity was recorded. Using the preference paradigm, we show that participants preferred to interact with the adaptive Viball rather than with the most slowly vibrating ball that most strongly reduced arousal. The stability of the human-ball coordination was the highest with the adaptive Viball. There was also a positive correlation between the stability of coordination and arousal. The data are discussed in light of the energy-based interpretation of coordination dynamics.

'The Mind' promotes brain synchronization: an ecological evaluation of brain synchronization in co-operative tasks

This paper presents an ecologically valid approach for using EEG hyperscanning methods to assess levels of interbrain synchrony (IBS) in teams during co-operative tasks. We employ a card-based task in an out-of-the-lab setting to evaluate levels of neural synchrony between team members completing a co-operative task. We also examine the interplay between the recorded synchronization levels and the collective performance of the team.Clinical Relevance- This study provides a simplistic and ecologically valid setup with potential to bring a better understanding of brain synchronization in clinical settings where co-operation would improve outcomes, such as home care facilities and memory clinics.

Virtual social interactions during the COVID-19 pandemic: the effect of interpersonal motor synchrony on social interactions in the virtual space

Although the link between motor synchrony and emotional alignment has been extensively studied during face-to-face interaction, the question of whether this association also exists in virtual settings has remained unanswered. Here, we examined whether this link exists during virtual social interactions and whether pro-social effects will be induced during those interactions. To this end, two strangers shared difficulties they have experienced due to the COVID-19 pandemic during a virtual social interaction that included both audio and video. The findings revealed that motor synchrony and emotional alignment can arise spontaneously during a virtual social interaction between two strangers. Moreover, this interaction yielded a decrease in negative affect and an increase in positive affect, as well as an increase in feelings of trust, liking, cohesion, self-other overlap, and similarity between the strangers. Finally, a higher level of synchrony during the virtual interaction was specifically associated with increased positive emotional alignment and liking. It can thus be presumed that virtual social interactions may share similar characteristics and social effects as face-to-face interactions. Considering the tremendous changes the COVID-19 pandemic has caused regarding social communication, these findings may provide grounds for developing new intervention protocols aimed at dealing with the consequences of social distancing.

Can rhythm-mediated reward boost learning, memory, and social connection? Perspectives for future research

Studies of rhythm processing and of reward have progressed separately, with little connection between the two. However, consistent links between rhythm and reward are beginning to surface, with research suggesting that synchronization to rhythm is rewarding, and that this rewarding element may in turn also boost this synchronization. The current mini review shows that the combined study of rhythm and reward can be beneficial to better understand their independent and combined roles across two central aspects of cognition: 1) learning and memory, and 2) social connection and interpersonal synchronization; which have so far been studied largely independently. From this basis, it is discussed how connections between rhythm and reward can be applied to learning and memory and social connection across different populations, taking into account individual differences, clinical populations, human development, and animal research. Future research will need to consider the rewarding nature of rhythm, and that rhythm can in turn boost reward, potentially enhancing other cognitive and social processes.

Antiphase synchrony increases perceived entitativity and uniqueness: A joint hand-clapping task

In- and antiphase are the dominant patterns identified in the study of synchrony in relative phases. Many previous studies have focused on in-phase synchrony and compared it to asynchrony, but antiphase synchrony has yet not been the subject of much research attention. The limited findings on antiphase synchrony suggest that its role or nature is unclear or unstable in human interaction. To account for this factor, this study examined the possibility that antiphase synchrony simultaneously induced perceived entitativity and uniqueness. The results of an experiment employing a joint hand-clapping task supported this prediction. Further, the elevated feeling of uniqueness in those who experienced antiphase synchrony may have increased the self-other overlap for those who felt oneness with their partner, but it decreased overlap for those who did not. The theoretical implications for synchrony literature are discussed.

Musical engagement as a duet of tight synchrony and loose interpretability

Joint engagement in music often facilitates positive social interaction, effectively shifting participants' perspective from the individual to the collective. The result is tight coordination and uniformity between participants, but at the same time, also remarkable flexibility and creativity. How does music achieve such a fine balance between the strict alignment necessary for coordination, and the substantial latitude necessary for experimentation? To address this question, I propose to analyze joint music engagement within the tight-loose theoretical framework broadly used in the social sciences. Tight-loose theory was originally developed for distinguishing between two archetypical cultural tendencies. On the one hand, tightness, which denotes stringent adherence to social norms, and on the other hand, looseness, which refers to a more flexible and less restrictive attitude towards norms. I posit that the flexible form of collaboration characteristic of musical interaction is due to a coexistence of tightness and looseness within joint engagement in music. I argue that the tight aspects of music can be attributed to its rhythmic structure, which requires continuous and precise temporal alignment between participants. Indeed, when experienced on its own, outside of a musical context, interpersonal synchrony has been repeatedly shown to enhance diverse positive social capacities such as bonding, collaboration and affiliation between interacting individuals, but at the expense of increasing conformity, blind obedience and even hostility towards non-group members. These effects are consistent with synchrony driving a tight interaction, inducing a sense of common group membership (CGM), which can endow music with necessary rigor and order. In contrast, the loose side of music may pertain to the ambiguity in meaning and intention expressed by music, which leaves ample room for interpretation and improvisation. I thus propose that the combined tight-loose nature of music, can simultaneously enhance positive social behaviors and reduce negative ones, leading to a tolerant form of group membership (TGM).

Korrika, running in collective effervescence through the Basque Country: A model of collective processes and their positive psychological effects

The neo-Durkheimnian model suggests that feedback and emotional communion between participants during a collective gathering (i.e., perceived emotional synchrony: PES) is one of the key mechanisms of collective processes. This shared emotional experience gives rise, in turn, to more intense emotions, this being one of the explanatory models of the positive psychological effects of collective participation. Through a quasi-longitudinal design of three measurement-times (N = 273, 65.9% women; age: 18-70, M = 39.43, SD = 11.64), the most massive social mobilization that is celebrated in favor of the Basque language in the Basque Country (Korrika) was analyzed. Repeated measures and sequential mediation analyzes supported the model. The effect of participation on social integration was mediated by the increase in emotions of enjoyment through PES; the effect on social acceptance, social contribution, and social actualization was mediated by increased kama muta through PES; the effect on collective empowerment was mediated by the increase in self-transcendent emotions through PES; and the effect on remembered well-being was partially mediated by PES. Finally, it was also verified for the first time that the effect of participation on social integration, social acceptance and social actualization was maintained through PES (but not through emotions) for at least 6-7 weeks after the event ended. Also, it is concluded that Kama muta is a relevant emotion during collective gatherings.

Smaller preferred interpersonal distance for joint versus parallel action

During social interaction, humans prefer to keep a certain distance between themselves and other individuals. This preferred 'interpersonal distance' (IPD) is known to be sensitive to social context, and in the present study we aimed to further investigate the extent to which IPD is affected by the specific type of social interaction. In particular, we focused on the contrast between joint actions, where two or more individuals coordinate their actions in space and time to achieve a shared goal, and parallel actions, where individuals act alongside each other but individually. We predicted that joint action would be associated with a smaller preferred IPD compared to parallel action. Additionally, given that this research took place in the midst of the COVID-19 pandemic, we aimed to assess whether IPD preferences are affected by individuals' concerns about infection in general, as well as COVID-19 in particular. We predicted that higher individual concerns would be associated with greater preferred IPD. To test these hypotheses, we asked participants to imagine different social scenarios (involving either joint or parallel actions alongside a stranger) and indicate, on a visual scale, their preferred IPD. The results of two experiments (n = 211, n = 212) showed that participants preferred a shorter distance when they imagined acting jointly compared to when they imagined acting in parallel. Moreover, participants who reported higher discomfort for potential pathogen contact and who were more aware of the COVID-19 context in which the study took place preferred a larger IPD in general. Our results provide further evidence that different types of social interaction shape IPD preference. We discuss potential reasons for this phenomenon and highlight remaining questions for future research.

Expectancy Effects Threaten the Inferential Validity of Synchrony-Prosociality Research

Many studies argue that synchronized movement increases prosocial attitudes and behavior. We reviewed meta-analytic evidence that reported effects of synchrony may be driven by experimenter expectancy, leading to experimenter bias; and participant expectancy, otherwise known as placebo effects. We found that a majority of published studies do not adequately control for experimenter bias and that multiple independent replication attempts with added controls have failed to find the original effects. In a preregistered experiment, we measured participant expectancy directly, asking whether participants have a priori expectations about synchrony and prosociality that match the findings in published literature. Expectations about the effects of synchrony on prosocial attitudes directly mirrored previous experimental findings (including both positive and null effects)-despite the participants not actually engaging in synchrony. On the basis of this evidence, we propose an alternative account of the reported bottom-up effects of synchrony on prosociality: the effects of synchrony on prosociality may be explicable as the result of top-down expectations invoked by placebo and experimenter effects.

Toward Causal Understanding of Therapist-Client Relationships: A Study of Language Modality and Social Entrainment

The relationship between a therapist and their client is one of the most critical determinants of successful therapy. The working alliance is a multifaceted concept capturing the collaborative aspect of the therapist-client relationship; a strong working alliance has been extensively linked to many positive therapeutic outcomes. Although therapy sessions are decidedly multimodal interactions, the language modality is of particular interest given its recognized relationship to similar dyadic concepts such as rapport, cooperation, and affiliation. Specifically, in this work we study language entrainment, which measures how much the therapist and client adapt toward each other's use of language over time. Despite the growing body of work in this area, however, relatively few studies examine causal relationships between human behavior and these relationship metrics: does an individual's perception of their partner affect how they speak, or does how they speak affect their perception? We explore these questions in this work through the use of structural equation modeling (SEM) techniques, which allow for both multilevel and temporal modeling of the relationship between the quality of the therapist-client working alliance and the participants' language entrainment. In our first experiment, we demonstrate that these techniques perform well in comparison to other common machine learning models, with the added benefits of interpretability and causal analysis. In our second analysis, we interpret the learned models to examine the relationship between working alliance and language entrainment and address our exploratory research questions. The results reveal that a therapist's language entrainment can have a significant impact on the client's perception of the working alliance, and that the client's language entrainment is a strong indicator of their perception of the working alliance. We discuss the implications of these results and consider several directions for future work in multimodality.

Nonverbal Synchrony in Technology-Mediated Interviews: A Cross-Cultural Study

Technology-mediated communication has changed the way we interact. Since the onset of the COVID-19 pandemic in March 2020, this trend became even more pronounced. Media interviews are no exception. Yet, studies on nonverbal behaviors, especially nonverbal synchrony during such mediated settings, have been scarce. To fill the research gap, this study investigated synchronized patterns between interview hosts' and guests' facial emotional displays and upper body movement during mediated interviews recorded in the countries in Western (mainly the US, with the addition of the UK) and Eastern cultures (Japan). The interviews were categorized into information- or entertainment-driven interviews, depending on the social attributes of the guest. The time series of the valence in facial displays and upper body movement was automatedly measured using FaceReader and Motion Energy Analysis software, respectively, which was analyzed in terms of simultaneous movements, a primary component of synchrony. As predicted, facial synchrony was more prevalent in information-driven interviews, supporting the motivational and strategic account of synchrony. In addition, female-hosted interviews had a higher degree of synchrony, especially in information-driven interviews. Similar patterns were seen in movement synchrony, although not significant. This study is the first evidence of synchrony in technology-mediated interviews in which a host and a guest appear on split-screen to inform or entertain audiences. However, no cultural differences in synchrony were observed. Situational demands in front of the interactants and the goal-driven nature of communication seemed to play a more prominent role than cultural differences in nonverbal synchrony.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10919-022-00416-3.

Shared emotions in shared lives: Moments of co-experienced affect, more than individually experienced affect, linked to relationship quality

Motivated by collective emotions theories that propose emotions shared between individuals predict group-level qualities, we hypothesized that co-experienced affect during interactions is associated with relationship quality, above and beyond the effects of individually experienced affect. Consistent with positivity resonance theory, we also hypothesized that co-experienced positive affect would have a stronger association with relationship quality than would co-experienced negative affect. We tested these hypotheses in 150 married couples across 3 conversational interactions: a conflict, a neutral topic, and a pleasant topic. Spouses continuously rated their individual affective experience during each conversation while watching video-recordings of their interactions. These individual affect ratings were used to determine, for positive and negative affect separately, the number of seconds of co-experienced affect and individually experienced affect during each conversation. In line with hypotheses, results from all 3 conversational topics suggest that more co-experienced positive affect is associated with greater marital quality, whereas more co-experienced negative affect is associated with worse marital quality. Individual level affect factors added little explanatory value beyond co-experienced affect. Comparing co-experienced positive affect and co-experienced negative affect, we found that co-experienced positive affect generally outperformed co-experienced negative affect, although co-experienced negative affect was especially diagnostic during the pleasant conversational topic. Findings suggest that co-experienced positive affect may be an integral component of high-quality relationships and highlight the power of co-experienced affect for individual perceptions of relationship quality. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Inter-brain plasticity as a biological mechanism of change in psychotherapy: A review and integrative model

Recent models of psychopathology and psychotherapy highlight the importance of interpersonal factors. The current review offers a biological perspective on these interpersonal processes by examining inter-brain synchrony-the coupling of brain activity between people interacting with one another. High inter-brain synchrony is associated with better relationships in therapy and in daily life, while deficits in the ability to achieve inter-brain synchrony are associated with a variety of psychological and developmental disorders. The review suggests that therapy improves patients' ability to achieve such synchrony through inter-brain plasticity-a process by which recurring exposure to high inter-brain synchrony leads to lasting change in a person's overall ability to synchronize. Therapeutic sessions provide repeated situations with high inter-brain synchrony. This can lead to a long-term increase in the ability to synchronize, first with the therapist, then generalized to other interpersonal relationships, ultimately leading to symptom reduction. The proposed inter-brain plasticity model offers a novel biological framework for understanding relational change in psychotherapy and its links to various forms of psychopathology and provides testable hypotheses for future research. Understanding this mechanism may help improve existing psychotherapy methods and develop new ones.

Following Other People's Footsteps: A Contextual-Attraction Effect Induced by Biological Motion

Our visual system is bombarded with numerous social interactions that form intangible social bonds among people, as exemplified by synchronized walking in crowds. Here, we investigated whether these perceived social bonds implicitly intrude on visual perception and induce a contextual effect. Using multiple point-light walkers and a classical contextual paradigm, we tested 72 college-age adults across six experiments and found that the perceived direction of the central walker was attracted toward the direction of the surrounding walkers. The observed contextual-attraction effect occurred even when the surrounding walkers differed from the central walker in gender and walking speed but disappeared when they were asynchronously presented or replaced by inanimate motion. Strikingly, this contextual-attraction effect partially persisted in the context of local motion rather than static figures. These findings, in contrast to the typical contextual-repulsion effect, lend support for the distinctiveness of perceived social bonds on contextual modulation and suggest a specialized contextual mechanism tuned to social factors.

Nonverbal synchrony in subjects with hearing impairment and their significant others

Introduction

Hearing loss has a great impact on the people affected, their close partner and the interaction between both, as oral communication is restricted. Nonverbal communication, which expresses emotions and includes implicit information on interpersonal relationship, has rarely been studied in people with hearing impairment (PHI). In psychological settings, non-verbal synchrony of body movements in dyads is a reliable method to study interpersonal relationship.

Material and methods

A 10-min social interaction was videorecorded in 39 PHI (29 spouses and 10 parent-child dyads) and their significant others (SOs). Nonverbal synchrony, which means the nonverbal behaviors of two interacting persons (referring to both general synchrony and the role of leading) and verbal interaction (percentage of speech, frequency of repetitions, and queries) were analyzed by computer algorithms and observer ratings. Hearing-related quality of life, coping mechanisms, general psychopathology, quality of relationship, and burden of hearing loss experienced by SOs were assessed using questionnaires.

Results

In the 39 dyads, true nonverbal synchrony differed from pseudosynchrony [t (43.4) = 2.41; p = 0.02] with a medium effect size (d = 0.42). Gender of PHI had a significant effect on general synchrony (p = 0.025) and on leading by SOs (p = 0.017). Age gap correlated with synchronic movements (p = 0.047). Very short duration of hearing impairment was associated with lower nonverbal synchrony in the role of leading by SOs (p = 0.031). Feeling of closeness by PHI correlated negatively with the role of leading by SOs (p > 0.001) and feeling of closeness by SOs was positively associated with leading by PHI (p = 0.015). No correlation was detected between nonverbal synchrony and other questionnaires. Burden experienced by the SOs was higher in SOs who reported less closeness (p = 0.014).

Discussion

A longer hearing impairment leads to more nonverbal leading by SOs compared to PHI with very short duration of hearing loss, possibly because of the long-lasting imbalance in communication. If PHI felt more closeness, SOs led less and vice versa. Burden experienced by SOs negatively correlated with closeness reported by SOs. Use of nonverbal signals and communication might help to improve benefits of auditory rehabilitation for PHI and decrease burden experienced by SOs.

The Wither or Thrive Model of Resilience: an Integrative Framework of Dynamic Vulnerability and Resilience in the Face of Repeated Stressors During the COVID-19 Pandemic

During the first 2 years of the COVID-19 pandemic, empirical efforts in the psychological sciences have been unequivocally focused on understanding the psychosocial impact on resilience and vulnerability. While current empirical work is guided by different existing theoretical models of resilience and vulnerability, the emerging datasets have also pointed to a necessity for an update of these models. Due to the unique features and developments specific to the current pandemic such as the occurrence of repeated collective stressors of varying durations, in the current position paper, we introduce the Wither or Thrive model of Resilience (With:Resilience). It integrates key aspects of prevailing psychological resilience frameworks within the context of the COVID-19 pandemic, and extends them by (1) moving away from single scale approaches towards a higher-order latent expression of resilience and vulnerability incorporating also non-clinical mental health markers, (2) proposing different trajectories of resilience-vulnerability emerging across repeated stressors over long periods of time, and (3) by incorporating multiple influencing factors including aspects of the socio-economic concept of social cohesion as well as separate mediating processing mechanisms. We propose that With:Resilience will enable a more nuanced approach and appropriate analytical investigation of the vast incoming data on mental health and resilience during the COVID-19 pandemic, and we suggest some concrete methodological approaches. This framework will assist in the development of actionable public health guidelines for society in the present and future pandemic contexts as well as aid policy making and the interventional sciences aimed at protecting the most vulnerable amongst us.

Interpersonal Physiological Synchrony Predicts Group Cohesion

A key emergent property of group social dynamic is synchrony–the coordination of actions, emotions, or physiological processes between group members. Despite this fact and the inherent nested structure of groups, little research has assessed physiological synchronization between group members from a multi-level perspective, thus limiting a full understanding of the dynamics between members. To address this gap of knowledge we re-analyzed a large dataset (N = 261) comprising physiological and psychological data that were collected in two laboratory studies that involved two different social group tasks. In both studies, following the group task, members reported their experience of group cohesion via questionnaires. We utilized a non-linear analysis method-multidimensional recurrence quantification analysis that allowed us to represent physiological synchronization in cardiological interbeat intervals between group members at the individual-level and at the group-level. We found that across studies and their conditions, the change in physiological synchrony from baseline to group interaction predicted a psychological sense of group cohesion. This result was evident both at the individual and the group levels and was not modified by the context of the interaction. The individual- and group-level effects were highly correlated. These results indicate that the relationship between synchrony and cohesion is a multilayered construct. We re-affirm the role of physiological synchrony for cohesion in groups. Future studies are needed to crystallize our understanding of the differences and similarities between synchrony at the individual-level and synchrony at the group level to illuminate under which conditions one of these levels has primacy, or how they interact.

Synchrony During Online Encounters Affects Social Affiliation and Theory of Mind but Not Empathy

Moving together in time affects human social affiliation and cognition. However, it is unclear whether these effects hold for on-line video meetings and whether they extend to empathy (understanding or sharing others' emotions) and theory of mind (ToM; attribution of mental states to others). 126 young adult participants met through online video in unacquainted pairs. Participants either performed 3 min of synchronous arm movements paced by sounds (n = 40), asynchronous movements (n = 46) or a small talk condition (n = 40). In a subsequent empathy task, participants engaged in a conversation. A video recording of this conversation was played back, and each participant rated, at predetermined time points, how they felt and how they thought their partner felt. From this we calculated empathic accuracy (accuracy of the estimation of the other's emotions) and emotional congruence (emotion sharing). ToM was measured by showing videos of geometrical shapes interacting and asking the participants to describe what happened, measuring the amount of intentionality. We found that participants in the synchrony condition rated feeling greater closeness and similarity to their partners relative to the asynchronous condition. Further, participants in the synchrony group tended to ascribe more intentionality to the abstract shapes than participants in asynchrony condition, suggesting greater ToM. Synchrony and asynchrony groups did not reliably differ in empathic accuracy nor emotional congruence. These results suggest that moving in synchrony has effects on social affiliation measures even in online encounters. These effects extend to ToM tendencies but not empathic accuracy or emotion sharing. These results highlight the potential of synchronous movement in online encounters to affect a subset of social cognition and affiliation measures.

The Components of Interpersonal Synchrony in the Typical Population and in Autism: A Conceptual Analysis

Interpersonal synchrony - the tendency for social partners to temporally co-ordinate their behaviour when interacting - is a ubiquitous feature of social interactions. Synchronous interactions play a key role in development, and promote social bonding and a range of pro-social behavioural outcomes across the lifespan. The process of achieving and maintaining interpersonal synchrony is highly complex, with inputs required from across perceptual, temporal, motor, and socio-cognitive domains. In this conceptual analysis, we synthesise evidence from across these domains to establish the key components underpinning successful non-verbal interpersonal synchrony, how such processes interact, and factors that may moderate their operation. We also consider emerging evidence that interpersonal synchrony is reduced in autistic populations. We use our account of the components contributing to interpersonal synchrony in the typical population to identify potential points of divergence in interpersonal synchrony in autism. The relationship between interpersonal synchrony and broader aspects of social communication in autism are also considered, together with implications for future research.

The intrapersonal and interpersonal consequences of interpersonal synchrony

Interpersonal synchrony, the time-matching behaviors, is pervasive in human interactions. This resonation of movements or other forms was generally considered as one of critical survival skills for humans, as the important consequences of synchronizing with other persons in review of the empirical data in this article. These include positive affects towards and between interacting partners, but also include complex effects on the individual level. The intrapersonal effects of interpersonal synchrony are varied with positive or negative ones, including cognitive style, attitude bias, mood state, self-regulatory ability, and academic performance. At the interpersonal level, synchronized movement consistently affects the interaction with the partner and his/her affiliations, but they can be eliminated or magnified by several moderators, such as physiological arousal, shared intentionality, group bias, and musical rhythm. Finally, the research discussed the possible mechanisms underlying the effects of interpersonal synchrony in psychological and biological aspects.

It Takes Two: Interpersonal Neural Synchrony Is Increased after Musical Interaction

Music’s deeply interpersonal nature suggests that music-derived neuroplasticity relates to interpersonal temporal dynamics, or synchrony. Interpersonal neural synchrony (INS) has been found to correlate with increased behavioral synchrony during social interactions and may represent mechanisms that support them. As social interactions often do not have clearly delineated boundaries, and many start and stop intermittently, we hypothesize that a neural signature of INS may be detectable following an interaction. The present study aimed to investigate this hypothesis using a pre-post paradigm, measuring interbrain phase coherence before and after a cooperative dyadic musical interaction. Ten dyads underwent synchronous electroencephalographic (EEG) recording during silent, non-interactive periods before and after a musical interaction in the form of a cooperative tapping game. Significant post-interaction increases in delta band INS were found in the post-condition and were positively correlated with the duration of the preceding interaction. These findings suggest a mechanism by which social interaction may be efficiently continued after interruption and hold the potential for measuring neuroplastic adaption in longitudinal studies. These findings also support the idea that INS during social interaction represents active mechanisms for maintaining synchrony rather than mere parallel processing of stimuli and motor activity.

Associations Between Sympathetic Nervous System Synchrony, Movement Synchrony, and Speech in Couple Therapy

Background

Research on interpersonal synchrony has mostly focused on a single modality, and hence little is known about the connections between different types of social attunement. In this study, the relationship between sympathetic nervous system synchrony, movement synchrony, and the amount of speech were studied in couple therapy.

Methods

Data comprised 12 couple therapy cases (24 clients and 10 therapists working in pairs as co-therapists). Synchrony in electrodermal activity, head and body movement, and the amount of speech and simultaneous speech during the sessions were analyzed in 12 sessions at the start of couple therapy (all 72 dyads) and eight sessions at the end of therapy (48 dyads). Synchrony was calculated from cross-correlations using time lags and compared to segment-shuffled pseudo synchrony. The associations between the synchrony modalities and speech were analyzed using complex modeling (Mplus).

Findings

Couple therapy participants' synchrony mostly occurred in-phase (positive synchrony). Anti-phase (negative) synchrony was more common in movement than in sympathetic nervous system activity. Synchrony in sympathetic nervous system activity only correlated with movement synchrony between the client-therapist dyads (r = 0.66 body synchrony, r = 0.59 head synchrony). Movement synchrony and the amount of speech correlated negatively between spouses (r = -0.62 body synchrony, r = -0.47 head synchrony) and co-therapists (r = -0.39 body synchrony, r = -0.28 head synchrony), meaning that the more time the dyad members talked during the session, the less bodily synchrony they exhibited.

Conclusion

The different roles and relationships in couple therapy were associated with the extent to which synchrony modalities were linked with each other. In the relationship between clients and therapists, synchrony in arousal levels and movement "walked hand in hand", whereas in the other relationships (spouse or colleague) they were not linked. Generally, more talk time by the therapy participants was associated with anti-phase movement synchrony. If, as suggested, emotions prepare us for motor action, an important finding of this study is that sympathetic nervous system activity can also synchronize with that of others independently of motor action.