Brainstorming: Interbrain coupling in groups forms the basis of group creativity.

Although the impact of group dynamics on creativity is widely recognized, prior research has primarily concentrated on individuals in isolation from social context. To address this lacuna, we focus on groups as the fundamental unit of analysis. We used functional near-infrared spectroscopy (fNIRS) to examine brain activity in groups of four during brainstorming discussions. We assessed interbrain coupling in the dorsolateral prefrontal cortex (DLPFC), a brain region linked to flexibility, and in the inferior frontal gyrus (IFG), a region associated with imitation. Our findings demonstrate that creativity-focused discussions induced interbrain coupling both in regions related to flexibility and herding. Notably, interbrain coupling in the IFG was associated with more imitation of responses. Critically, while interbrain coupling in the DLPFC positively predicted group creativity, in the IFG it negatively predicted creativity. These findings suggest that increase in group mindsets of flexibility relative to herding is important for enhancing group creativity.

Post-interaction neuroplasticity of inter-brain networks underlies the development of social relationship.

Inter-brain coupling has been increasingly recognized for its role in supporting connectedness during social communication. Here we investigate whether inter-brain coupling is plastic and persists beyond the offset of social interaction, facilitating the emergence of social closeness. Dyads were concurrently scanned using functional near infrared spectroscopy (fNIRS) while engaging in a task that involved movement synchronization. To assess post-interaction neuroplasticity, participants performed a baseline condition with no interaction before and after the interaction. The results reveal heightened inter-brain coupling in neural networks comprising the inferior frontal gyrus (IFG) and dorsomedial prefrontal cortex in the post-task compared to the pre-task baseline. Critically, the right IFG emerged as a highly connected hub, with post-task inter-brain coupling in this region predicting the levels of motivation to connect socially. We suggest that post-interactions inter-brain coupling may reflect consolidation of socially related cues, underscoring the role of inter-brain plasticity in fundamental aspects of relationship development.

Away from the herd: loneliness as a dysfunction of social alignment.

The tendency of all humans to experience loneliness at some point in their lives implies that it serves an adaptive function. Building on biological theories of herding in animals, according to which collective movement emerges from local interactions that are based on principles of attraction, repulsion and alignment, we propose an approach that synthesizes these principles with theories of loneliness in humans. We present here the 'herding model of loneliness' that extends these principles into the psychological domain. We hold that these principles serve as basic building blocks of human interactions and propose that distorted attraction and repulsion tendencies may lead to inability to align properly with others, which may be a core component in loneliness emergence and perpetuation. We describe a neural model of herding in humans and suggest that loneliness may be associated with altered interactions between the gap/error detection, reward signaling, threat and observation-execution systems. The proposed model offers a framework to predict the behavior of lonely individuals and thus may inform intervention designs for reducing loneliness intensity.

Differential contribution of between and within-brain coupling to movement synchronization.

A fundamental characteristic of the human brain that supports behavior is its capacity to create connections between brain regions. A promising approach holds that during social behavior, brain regions not only create connections with other brain regions within a brain, but also coordinate their activity with other brain regions of an interaction partner. Here we ask whether between-brain and within-brain coupling contribute differentially to movement synchronization. We focused on coupling between the inferior frontal gyrus (IFG), a brain region associated with the observation-execution system, and the dorsomedial prefrontal cortex (dmPFC), a region associated with error-monitoring and prediction. Participants, randomly divided into dyads, were simultaneously scanned with functional near infra-red spectroscopy (fNIRS) while performing an open-ended 3D hand movement task consisting of three conditions: back-to-back movement, free movement, or intentional synchronization. Results show that behavioral synchrony was higher in the intentional synchrony compared with the back-to-back and free movement conditions. Between-brain coupling in the IFG and dmPFC was evident in the free movement and intentional synchrony conditions but not in the back-to-back condition. Importantly, between-brain coupling was found to positively predict intentional synchrony, while within-brain coupling was found to predict synchronization during free movement. These results indicate that during intentional synchronization, brain organization changes such that between-brain networks, but not within-brain connections, contribute to successful communication, pointing to shift from a within-brain feedback loop to a two-brains feedback loop.

The benefits of learning movement sequences in social interactions.

Although we frequently acquire knowledge and skills through social interactions, the focus of most research on learning is on individual learning. Here we characterize Interaction Based Learning (IBL), which represents the acquisition of knowledge or skill through social interactions, and compare it to Observational Learning (OL)-learning by observation. To that end, we designed a movement synchronization paradigm whereby participants learned Tai-Chi inspired movement sequences from trained teachers in two separated sessions. We used a motion capture system to track the movement of 40 dyads comprised of a teacher and learner, who were randomly divided into OL or IBL groups, and calculated time-varying synchrony of three-dimensional movement velocity. While in the IBL group both the learner and the teacher could see each other through a transparent glass, in the OL group dyads interacted through a one-way mirror, such that the learners observed the teacher, but the teacher could not see the learners. Results show that although the number of movements recalled was not different between groups, we found improved movement smoothness in the IBL compared to the OL group, indicating movement acquisition was better in the IBL group. In addition, we found that motor synchronization levels in dyads improved over time, indicating that movement synchronization can be learned and retained. In the first session, the IBL group, but not the OL group, showed a significant improvement in synchronization. This suggests that dyadic interaction is important for learning movement sequences, and that bidirectional communication of signals and mutual feedback are essential for the consolidation of motor learning.

Behavioral and Neural Dissociation of Social Anxiety and Loneliness.

Loneliness is a public health concern with detrimental effects on physical and mental well-being. Given phenotypical overlaps between loneliness and social anxiety (SA), cognitive-behavioral interventions targeting SA might be adopted to reduce loneliness. However, whether SA and loneliness share the same underlying neurocognitive mechanisms is still an elusive question. The current study aimed at investigating to what extent known behavioral and neural correlates of social avoidance in SA are evident in loneliness. We used a prestratified approach involving 42 (21 females) participants with high loneliness (HL) and 40 (20 females) participants with low loneliness (LL) scores. During fMRI, participants completed a social gambling task to measure the subjective value of engaging in social situations and responses to social feedback. Univariate and multivariate analyses of behavioral and neural data replicated known task effects. However, although HL participants showed increased SA, loneliness was associated with a response pattern clearly distinct from SA. Specifically, contrary to expectations based on SA differences, Bayesian analyses revealed moderate evidence for equal subjective values of engaging in social situations and comparable amygdala responses to social decision-making and striatal responses to positive social feedback in both groups. Moreover, while explorative analyses revealed reduced pleasantness ratings, increased striatal activity, and decreased striatal-hippocampal connectivity in response to negative computer feedback in HL participants, these effects were diminished for negative social feedback. Our findings suggest that, unlike SA, loneliness is not associated with withdrawal from social interactions. Thus, established interventions for SA should be adjusted when targeting loneliness.SIGNIFICANCE STATEMENT Loneliness can cause serious health problems. Adapting well-established cognitive-behavioral therapies targeting social anxiety might be promising to reduce chronic loneliness given a close link between both constructs. However, a better understanding of behavioral and neurobiological factors associated with loneliness is needed to identify which specific mechanisms of social anxiety are shared by lonely individuals. We found that lonely individuals show a consistently distinct pattern of behavioral and neural responsiveness to social decision-making and social feedback compared with previous findings for social anxiety. Our results indicate that loneliness is associated with a biased emotional reactivity to negative events rather than social avoidance. Our findings thus emphasize the distinctiveness of loneliness from social anxiety and the need for adjusted psychotherapeutic protocols.

Altered activation in the action observation system during synchronization in high loneliness individuals.

Lonely people tend to evaluate social exchanges negatively and to display difficulties in interactions. Interpersonal synchronization is crucial for achieving positive interactions, promoting affinity, closeness, and satisfaction. However, little is known about lonely individuals' ability to synchronize and about their brain activity while synchronizing. Following the screening of 303 participants, we recruited 32 low and 32 high loneliness participants. They were scanned while engaged in movement synchronization, using a novel dyadic interaction paradigm. Results showed that high loneliness individuals exhibited a reduced ability to adapt their movement to their partner's movement. Intriguingly, during movement adaptation periods, high loneliness individuals showed increased activation in the action observation (AO) system, specifically in the inferior frontal gyrus and the inferior parietal lobule. They did not show increased activation in the dorsomedial prefrontal cortex, which in the context of synchronization was suggested to be related to gap-monitoring. Based on these findings, we propose a model according to which lonely people may require stronger activation of their AO system for alignment, to compensate for some deficiency in their synchronization ability. Despite this hyperactivation, they still suffer from reduced synchronization capacity. Consequently, synchronization may be a relevant intervention area for the amelioration of loneliness.

Adaptive Empathy: A Model for Learning Empathic Responses in Response to Feedback.

Empathy is usually deployed in social interactions. Nevertheless, common measures and examinations of empathy study this construct in isolation from the person in distress. In this article we seek to extend the field of examination to include both empathizer and target to determine whether and how empathic responses are affected by feedback and learned through interaction. Building on computational approaches in feedback-based adaptations (e.g., no feedback, model-free and model-based learning), we propose a framework for understanding how empathic responses are learned on the basis of feedback. In this framework, adaptive empathy, defined as the ability to adapt one's empathic responses, is a central aspect of empathic skills and can provide a new dimension to the evaluation and investigation of empathy. By extending existing neural models of empathy, we suggest that adaptive empathy may be mediated by interactions between the neural circuits associated with valuation, shared distress, observation-execution, and mentalizing. Finally, we propose that adaptive empathy should be considered a prominent facet of empathic capabilities with the potential to explain empathic behavior in health and psychopathology.

Touched by loneliness-how loneliness impacts the response to observed human touch: a tDCS study.

Lonely people often crave connectedness. However, they may also experience their environment as threatening, entering a self-preserving state that perpetuates loneliness. Research shows conflicting evidence about their response to positive social cues, and little is known about their experience of observed human touch. The right inferior frontal gyrus (rIFG) is part of an observation-execution network implicated in observed touch perception. Correlative studies also point to rIFG's involvement in loneliness. We examined the causal effect of rIFG anodal transcranial direct current stimulation on high- and low-loneliness individuals observing human touch. In a cross-over design study, 40 participants watched pictures of humans or objects touching or not touching during anodal and sham stimulations. Participants indicated whether pictures contained humans or objects, and their reaction time was measured. Results show that the reaction time of low-loneliness individuals to observed human touch was significantly slower during anodal stimulation compared to high-loneliness individuals, possibly due to them being more emotionally distracted by it. Lonely individuals also reported less liking of touch. Our findings support the notion that lonely individuals are not drawn to positive social cues. This may help explain the perpetuation of loneliness, despite social opportunities that could be available to lonely people.

Brains that Fire Together Wire Together: Interbrain Plasticity Underlies Learning in Social Interactions.

Social interactions are powerful determinants of learning. Yet the field of neuroplasticity is deeply rooted in probing changes occurring in synapses, brain structures, and networks within an individual brain. Here I synthesize disparate findings on network neuroplasticity and mechanisms of social interactions to propose a new approach for understanding interaction-based learning that focuses on the dynamics of interbrain coupling. I argue that the facilitation effect of social interactions on learning may be explained by interbrain plasticity, defined here as the short- and long-term experience-dependent changes in interbrain coupling. The interbrain plasticity approach may radically change our understanding of how we learn in social interactions.

Loneliness and the Social Brain: How Perceived Social Isolation Impairs Human Interactions.

Loneliness is a painful condition associated with increased risk for premature mortality. The formation of new, positive social relationships can alleviate feelings of loneliness, but requires rapid trustworthiness decisions during initial encounters and it is still unclear how loneliness hinders interpersonal trust. Here, a multimodal approach including behavioral, psychophysiological, hormonal, and neuroimaging measurements is used to probe a trust-based mechanism underlying impaired social interactions in loneliness. Pre-stratified healthy individuals with high loneliness scores (n = 42 out of a screened sample of 3678 adults) show reduced oxytocinergic and affective responsiveness to a positive conversation, report less interpersonal trust, and prefer larger social distances compared to controls (n = 40). Moreover, lonely individuals are rated as less trustworthy compared to controls and identified by the blinded confederate better than chance. During initial trust decisions, lonely individuals exhibit attenuated limbic and striatal activation and blunted functional connectivity between the anterior insula and occipitoparietal regions, which correlates with the diminished affective responsiveness to the positive social interaction. This neural response pattern is not mediated by loneliness-associated psychological symptoms. Thus, the results indicate compromised integration of trust-related information as a shared neurobiological component in loneliness, yielding a reciprocally reinforced trust bias in social dyads.

Opposing Association of Situational and Chronic Loneliness with Interpersonal Distance.

Loneliness is a prevalent condition with adverse effects on physical and mental health. Evolutionary theories suggest it evolved to drive people to reconnect. However, chronic loneliness may result in a negative social bias and self-preservation behaviors, paradoxically driving individuals away from social interactions. Lonely people often feel they are not close to anyone; however, little is known about their interpersonal distance preferences. During COVID-19, many experienced situational loneliness related to actual social isolation. Therefore, there was a unique opportunity to examine both chronic and situational (COVID-19-related) loneliness. In the present study, 479 participants completed an online task that experimentally assessed interpersonal distance preferences in four conditions-passively being approached by a friend or a stranger, and actively approaching a friend or a stranger. Results show that high chronic loneliness was related to a greater preferred distance across conditions. Intriguingly, by contrast, high COVID-19-related loneliness was related to a smaller preferred distance across conditions. These findings provide further support for the evolutionary theory of loneliness: situational loneliness indeed seems to drive people towards reconnection, while chronic loneliness seems to drive people away from it. Implications for the amelioration of chronic loneliness are discussed based on these findings.

Adaptive Empathy: Empathic Response Selection as a Dynamic, Feedback-Based Learning Process.

Empathy allows us to respond to the emotional state of another person. Considering that an empathic interaction may last beyond the initial response, learning mechanisms may be involved in dynamic adaptation of the reaction to the changing emotional state of the other person. However, traditionally, empathy is assessed through sets of isolated reactions to another's distress. Here we address this gap by focusing on adaptive empathy, defined as the ability to learn and adjust one's empathic responses based on feedback. For this purpose, we designed a novel paradigm of associative learning in which participants chose one of two empathic strategies (reappraisal or distraction) to attenuate the distress of a target person, where one strategy had a higher probability of relieving distress. After each choice, participants received feedback about the success of their chosen strategy in relieving the target person's distress, which they could use to inform their future decisions. The results show that the participants made more accurate choices in the adaptive empathy condition than in a non-social control condition, pointing to an advantage for learning from social feedback. We found a correlation between adaptive empathy and a trait measure of cognitive empathy. These findings indicate that the ability to learn about the effectiveness of empathic responses may benefit from incorporating mentalizing abilities. Our findings provide a lab-based model for studying adaptive empathy and point to the potential contribution of learning theory to enhancing our understanding of the dynamic nature of empathy.

The comfort in touch: Immediate and lasting effects of handholding on emotional pain.

Consoling touch is a powerful form of social support that has been repeatedly demonstrated to reduce the experience of physical pain. However, it remains unknown whether touch reduces emotional pain in the same way that it reduces physical pain. The present research sought to understand how handholding with a romantic partner shapes experiences of emotional pain and comfort during emotional recollection, as well as how it shapes lasting emotional pain associated with emotional experiences. Participants recalled emotionally painful memories or neutral memories with their partners, while holding their partner's hand or holding a squeeze-ball. They additionally completed a follow-up survey to report how much emotional pain they associated with the emotional experiences after recalling them in the lab with their partners. Although consoling touch did not reduce emotional pain during the task, consoling touch increased feelings of comfort. Moreover, participants later recalled emotional memories that were paired with touch as being less emotionally painful than those that were not paired with touch. These findings suggest that touch does not decrease the immediate experience of emotional pain and may instead support adaptive processing of emotional experiences over time.

You Name It: Interpersonal Affect Labeling Diminishes Distress in Romantic Couples.

Although it is increasingly acknowledged that social interactions may provide support at times of adversity, whether or how such interactions can buffer distress remains unclear. The objective of the present study was to examine whether naming the emotions of our partner in aversive situations can effectively reduce distress and whether the regulator's empathy contributes to its effectiveness. We utilized a novel performance-based interpersonal affect labeling (IAL) paradigm. Seventy-four romantic couples were randomly divided into targets and regulators. The targets watched aversive pictures with low and high intensity and rated their level of distress after: (1) simply viewing the picture (control trials) (2) choosing a label that describes their emotional reaction (self-labeling trials), (3) viewing a label chosen for them by the regulator, their partner (IAL trials). It was found that IAL significantly reduced distress compared to self-labeling. Moreover, the effectiveness of IAL increased as a function of the regulator's level of empathy. The results highlight the importance of empathy in social support and suggest that as simple an action as naming our partner's emotions may be effective in reducing their distress. Moreover, it emphasizes the potential contribution of nonprofessional help in emotion regulation.

A dual-brain approach for understanding the neuralmechanisms that underlie the comforting effects of social touch.

Across different cultures, social touch is used to alleviate distress. Here we adopt a dual-brain approach with fMRI to examine whether social touch involves similar activations between the suffering 'target' and the empathizer in brain regions related to emotional sharing such as the observation-execution (mirror) network. To inspect the neural underpinnings of the effects of social touch on pain, we scanned romantic couples during a task that required one partner (the empathizer) to hold the target's hand as the latter experienced painful thermal stimulation. Empathizers and target participants were scanned sequentially, in two counterbalanced phases. Results revealed that hand-holding reduced the pain of the target participant, compared to the severity of pain in a control condition (holding a rubber ball). Importantly, during social touch we found striking shared activations between the target and empathizer in the inferior parietal lobule (IPL), a region related to the observation-execution network. The brain-to-brain analysis further revealed a positive correlation of IPL activation levels between the target and the empathizer. Finally, psychophysiological interaction (PPI) analysis in the target showed that the IPL activity during social touch was positively coupled with activity in the dorsomedial prefrontal cortex, a region that has been implicated in emotion regulation, suggesting that the interaction between the observation-execution network and emotion regulation network may contribute to pain reduction during social touch.

Oxytocin increases the social salience of the outgroup in potential threat contexts.

A growing body of literature suggests that OT administration may affect not only prosocial outcomes, but also regulate adversarial responses in the context of intergroup relations. However, recent reports have challenged the view of a fixed role of OT in enhancing ingroup favoritism and outgroup derogation. Studying the potential effects of OT in modulating threat perception in a context characterized by racial miscegenation (Brazil) may thus afford additional clarification on the matter. In a double-blind, placebo-controlled study, White Brazilian participants completed a first-person shooter task to assess their responses towards potential threat from racial ingroup (White) or outgroup (Black) members. OT administration enhanced the social salience of the outgroup, by both increasing the rate at which participants refrained from shooting unarmed Black targets to levels similar to White targets, and by further increasing the rate of correct decisions to shoot armed Black targets (versus White armed targets). In summary, our results indicate that a single dose of OT may promote accurate behavioral responses to potential threat from members of a racial outgroup, thus offering support to the social salience hypothesis.

Women's Body Odor during Ovulation Improves Social Perception in Single Men.

Previous research has shown that men's mating motivation may increase following exposure to women's body odor during ovulation. In the current study, we examined whether exposure to women's fertility odor cues influences social perception among men, while focusing on the role of men's relationship status in moderating this reaction. We collected body odor samples from 43 women during ovulation and during the luteal phase and exposed 85 men to these odor samples while they performed an emotion recognition task and an interpersonal perception task. Single men were better at recognizing emotional facial expressions following exposure to odor cues of high fertility as compared with odor cues of low fertility. No such effect was identified in pair-bonded men. In support of this finding, single men became more accurate on the interpersonal perception task following exposure to odor cues of high fertility, while pair-bonded men became less accurate after such exposure. Collectively, the results suggest that exposure to women's fertility odor cues improves social perception among single men, while it impairs such perception among pair-bonded men. We suggest that these effects may result from increased mating motivation following exposure to odor cues of fertility, which in turn encourages accurate social perception among single men while promoting an avoidant attitude toward social stimuli among pair-bonded men.