Neural bases of recommendations differ according to social network structure

The detection of self-group conflicts in exercise behaviors differs with social network centrality: ERP evidence

BACKGROUND

The influence of social norms on exercise behaviors has been explored in studies over the years. However, little is known about whether an individual's role (central or peripheral) in his or her social network, which is associated with social skills, could shift his or her susceptibility to normative effects on exercise behaviors. To that end, event-related potentials (ERPs) were recorded to examine the underlying cognitive mechanism of the effects of network centrality on normative social influence.

METHODS

We manipulated network centrality by assigning participants to exercise support groups, with group members who were their nominated friends (high centrality) or nonnominated classmates (low centrality). Participants were asked to evaluate their willingness to engage in various exercises, after viewing discrepant group ratings (peer influence) or not viewing (no-influence).

RESULTS

Peer influence evoked a larger negative-going feedback-related negativity (FRN) wave, which was linked to automatic social conflict detection, and a larger positive-going P3 wave, which was linked to subsequent conformity behavioral changes. However, effects on the FRN, not the P3, were observed only in the high-centrality group.

CONCLUSION

Our results highlight the important roles of network centrality in encoding self-group exercise attitude discrepancy rather than in decision-making regarding exercise attitude adjustments. Interventions aimed at promoting exercise behaviors should be considered in a broader social environmental framework.

Being the Gatekeeper: How Thinking about Sharing Affects Neural Encoding of Information

Information transmission in a society depends on individuals' intention to share or not. Yet, little is known about whether being the gatekeeper shapes the brain's processing of incoming information. Here, we examine how thinking about sharing affects neural encoding of information, and whether this effect is moderated by the person's real-life social network position. In an functional magnetic resonance imaging study, participants rated abstracts of news articles on how much they wanted to read for themselves (read) or-as information gatekeepers-to share with a specific other (narrowcast) or to post on their social media feed (broadcast). In all conditions, consistent spatial blood oxygen level-dependent patterns associated with news articles were observed across participants in brain regions involved in perceptual and language processing as well as higher-order processes. However, when thinking about sharing, encoding consistency decreased in higher-order processing areas (e.g., default mode network), suggesting that the gatekeeper role involves more individualized processing in the brain, that is, person- and context-specific. Moreover, participants whose social networks had high ego-betweenness centrality (i.e., more likely to be information gatekeeper in real life) showed more individualized encoding when thinking about broadcasting. This study reveals how gatekeeping shapes our brain's processing of incoming information.

Response inhibition in adolescents is moderated by brain connectivity and social network structure

The social environment an individual is embedded in influences their ability and motivation to engage self-control processes, but little is known about the neural mechanisms underlying this effect. Many individuals successfully regulate their behavior even when they do not show strong activation in canonical self-control brain regions. Thus, individuals may rely on other resources to compensate, including daily experiences navigating and managing complex social relationships that likely bolster self-control processes. Here, we employed a network neuroscience approach to investigate the role of social context and social brain systems in facilitating self-control in adolescents. We measured brain activation using functional magnetic resonance imaging (fMRI) as 62 adolescents completed a Go/No-Go response inhibition task. We found that self-referential brain systems compensate for weaker activation in executive function brain systems, especially for adolescents with more friends and more communities in their social networks. Collectively, our results indicate a critical role for self-referential brain systems during the developmental trajectory of self-control throughout adolescence.

Social Capital on Social Networking Sites: A Social Network Perspective

Although social capital has been researched from many approaches and attempts have been made to measure it online, the literature lacks an operational description that would allow its measurement criteria to be established from a social network perspective. Therefore, the purpose of this paper is to identify in the literature what metrics researchers use to measure social capital on social networking sites from a social network perspective. Thus, this contribution offers a theoretical description of the key elements for measuring social capital in social networking sites, which may be useful in subsequent studies.

Neurobiological Bases of Social Networks

A social network is a web that integrates multiple levels of interindividual social relationships and has direct associations with an individual’s health and well-being. Previous research has mainly focused on how brain and social network structures (structural properties) act on each other and on how the brain supports the spread of ideas and behaviors within social networks (functional properties). The structure of the social network is correlated with activity in the amygdala, which links decoding and interpreting social signals and social values. The structure also relies on the mentalizing network, which is central to an individual’s ability to infer the mental states of others. Network functional properties depend on multilayer brain-social networks, indicating that information transmission is supported by the default mode system, the valuation system, and the mentalizing system. From the perspective of neuroendocrinology, overwhelming evidence shows that variations in oxytocin, β-endorphin and dopamine receptor genes, including oxytocin receptor (OXTR), mu opioid receptor 1 (OPRM1) and dopamine receptor 2 (DRD2), predict an individual’s social network structure, whereas oxytocin also contributes to improved transmission of emotional and behavioral information from person to person. Overall, previous studies have comprehensively revealed the effects of the brain, endocrine system, and genes on social networks. Future studies are required to determine the effects of cognitive abilities, such as memory, on social networks, the characteristics and neural mechanism of social networks in mental illness and how social networks change over time through the use of longitudinal methods.

Neural and social correlates of attitudinal brokerage: using the complete social networks of two entire villages

To avoid polarization and maintain small-worldness in society, people who act as attitudinal brokers are critical. These people maintain social ties with people who have dissimilar and even incompatible attitudes. Based on resting-state functional magnetic resonance imaging (n = 139) and the complete social networks from two Korean villages (n = 1508), we investigated the individual-level neural capacity and social-level structural opportunity for attitudinal brokerage regarding gender role attitudes. First, using a connectome-based predictive model, we successfully identified the brain functional connectivity that predicts attitudinal diversity of respondents' social network members. Brain regions that contributed most to the prediction included mentalizing regions known to be recruited in reading and understanding others’ belief states. This result was corroborated by leave-one-out cross-validation, fivefold cross-validation and external validation where the brain connectivity identified in one village was used to predict the attitudinal diversity in another independent village. Second, the association between functional connectivity and attitudinal diversity of social network members was contingent on a specific position in a social network, namely, the structural brokerage position where people have ties with two people who are not otherwise connected.

Navigating the Social Environment in Adolescence: The Role of Social Brain Development

Successful navigation of the social environment is dependent on a number of social cognitive processes, including mentalizing and resistance to peer influence. These processes continue to develop during adolescence, a time of significant social change, and are underpinned by regions of the social brain that continue to mature structurally and functionally into adulthood. In this review, we describe how mentalizing, peer influence, and emotion regulation capacities develop to aid the navigation of the social environment during adolescence. Heightened susceptibility to peer influence and hypersensitivity to social rejection in adolescence increase the likelihood of both risky and prosocial behavior in the presence of peers. Developmental differences in mentalizing and emotion regulation, and the corticosubcortical circuits that underpin these processes, might put adolescents at risk for developing mental health problems. We suggest how interventions aimed at improving prosocial behavior and emotion regulation abilities hold promise in reducing the risk of poor mental health as adolescents navigate the changes in their social environment.

Similarity in functional brain connectivity at rest predicts interpersonal closeness in the social network of an entire village

People often have the intuition that they are similar to their friends, yet evidence for homophily (being friends with similar others) based on self-reported personality is inconsistent. Functional connectomes-patterns of spontaneous synchronization across the brain-are stable within individuals and predict how people tend to think and behave. Thus, they may capture interindividual variability in latent traits that are particularly similar among friends but that might elude self-report. Here, we examined interpersonal similarity in functional connectivity at rest-that is, in the absence of external stimuli-and tested if functional connectome similarity is associated with proximity in a real-world social network. The social network of a remote village was reconstructed; a subset of residents underwent functional magnetic resonance imaging. Similarity in functional connectomes was positively related to social network proximity, particularly in the default mode network. Controlling for similarities in demographic and personality data (the Big Five personality traits) yielded similar results. Thus, functional connectomes may capture latent interpersonal similarities between friends that are not fully captured by commonly used demographic or personality measures. The localization of these results suggests how friends may be particularly similar to one another. Additionally, geographic proximity moderated the relationship between neural similarity and social network proximity, suggesting that such associations are particularly strong among people who live particularly close to one another. These findings suggest that social connectivity is reflected in signatures of brain functional connectivity, consistent with the common intuition that friends share similarities that go beyond, for example, demographic similarities.

Neurobiological Sensitivity to Social Rewards and Punishments Moderates Link Between Peer Norms and Adolescent Risk Taking

Although peer influence is a strong predictor of adolescents' risk-taking behaviors, not all adolescents are susceptible to their peer group. One hundred and thirty-six adolescents (M_age  = 12.79 years) completed an fMRI scan, measures of perceived peer group norms, and engagement in risky behavior. Ventral striatum (VS) sensitivity when anticipating social rewards and avoiding social punishments significantly moderated the association between perceived peer norms and adolescents' own risk behaviors. Perceptions of more deviant peer norms were associated with increased risky behavior, but only for adolescents with high VS sensitivity; adolescents with low VS sensitivity were resilient to deviant peer norms, showing low risk taking regardless of peer context. Findings provide a novel contribution to the study of peer influence susceptibility.

Social network analysis for social neuroscientists

Although social neuroscience is concerned with understanding how the brain interacts with its social environment, prevailing research in the field has primarily considered the human brain in isolation, deprived of its rich social context. Emerging work in social neuroscience that leverages tools from network analysis has begun to advance knowledge of how the human brain influences and is influenced by the structures of its social environment. In this paper, we provide an overview of key theory and methods in network analysis (especially for social systems) as an introduction for social neuroscientists who are interested in relating individual cognition to the structures of an individual’s social environments. We also highlight some exciting new work as examples of how to productively use these tools to investigate questions of relevance to social neuroscientists. We include tutorials to help with practical implementations of the concepts that we discuss. We conclude by highlighting a broad range of exciting research opportunities for social neuroscientists who are interested in using network analysis to study social systems.

Functional brain network architecture supporting the learning of social networks in humans

Most humans have the good fortune to live their lives embedded in richly structured social groups. Yet, it remains unclear how humans acquire knowledge about these social structures to successfully navigate social relationships. Here we address this knowledge gap with an interdisciplinary neuroimaging study drawing on recent advances in network science and statistical learning. Specifically, we collected BOLD MRI data while participants learned the community structure of both social and non-social networks, in order to examine whether the learning of these two types of networks was differentially associated with functional brain network topology. We found that participants learned the community structure of the networks, as evidenced by a slower reaction time when a trial moved between communities than when a trial moved within a community. Learning the community structure of social networks was also characterized by significantly greater functional connectivity of the hippocampus and temporoparietal junction when transitioning between communities than when transitioning within a community. Furthermore, temporoparietal regions of the default mode were more strongly connected to hippocampus, somatomotor, and visual regions for social networks than for non-social networks. Collectively, our results identify neurophysiological underpinnings of social versus non-social network learning, extending our knowledge about the impact of social context on learning processes. More broadly, this work offers an empirical approach to study the learning of social network structures, which could be fruitfully extended to other participant populations, various graph architectures, and a diversity of social contexts in future studies.

Self and Others in Adolescence

Research has demonstrated that adolescence is an important time for self- and other-oriented development that underlies many skills vital for becoming a contributing member of society with healthy intergroup relations. It is often assumed that these two processes, thinking about self and thinking about others, are pitted against each other when adolescents engage in social decision making such as giving or sharing. Recent evidence from social neuroscience, however, does not support this notion of conflicting motives, suggesting instead that thinking about self and others relies on a common network of social-affective brain regions, with the medial prefrontal cortex playing a central role in the integration of perspectives related to self and others. Here, we argue that self- and other-oriented thinking are intertwined processes that rely on an overlapping neural network. Adolescents’ motivation to contribute to society can be fostered most when self- and other-oriented motives align.

Individual EEG measures of attention, memory, and motivation predict population level TV viewership and Twitter engagement

Television (TV) programming attracts ever-growing audiences and dominates the cultural zeitgeist. Viewership and social media engagement have become standard indices of programming success. However, accurately predicting individual episode success or future show performance using traditional metrics remains a challenge. Here we examine whether TV viewership and Twitter activity can be predicted using electroencephalography (EEG) measures, which are less affected by reporting biases and which are commonly associated with different cognitive processes. 331 participants watched an hour-long episode from one of nine prime-time shows (~36 participants per episode). Three frequency-based measures were extracted: fronto-central alpha/beta asymmetry (indexing approach motivation), fronto-central alpha/theta power (indexing attention), and fronto-central theta/gamma power (indexing memory processing). All three EEG measures and the composite EEG score significantly correlated across episode segments with the two behavioral measures of TV viewership and Twitter volume. EEG measures explained more variance than either of the behavioral metrics and mediated the relationship between the two. Attentional focus was integral for both audience retention and Twitter activity, while emotional motivation was specifically linked with social engagement and program segments with high TV viewership. These findings highlight the viability of using EEG measures to predict success of TV programming and identify cognitive processes that contribute to audience engagement with television shows.

Social brain volume is associated with in-degree social network size among older adults

The social brain hypothesis proposes that large neocortex size evolved to support cognitively demanding social interactions. Accordingly, previous studies have observed that larger orbitofrontal and amygdala structures predict the size of an individual's social network. However, it remains uncertain how an individual's social connectedness reported by other people is associated with the social brain volume. In this study, we found that a greater in-degree network size, a measure of social ties identified by a subject's social connections rather than by the subject, significantly correlated with a larger regional volume of the orbitofrontal cortex, dorsomedial prefrontal cortex and lingual gyrus. By contrast, out-degree size, which is based on an individual's self-perceived connectedness, showed no associations. Meta-analytic reverse inference further revealed that regional volume pattern of in-degree size was specifically involved in social inference ability. These findings were possible because our dataset contained the social networks of an entire village, i.e. a global network. The results suggest that the in-degree aspect of social network size not only confirms the previously reported brain correlates of the social network but also shows an association in brain regions involved in the ability to infer other people's minds. This study provides insight into understanding how the social brain is uniquely associated with sociocentric measures derived from a global network.

Brain Sensitivity to Exclusion is Associated with Core Network Closure

Humans are driven to pursue and preserve social relationships, and these motivations are reinforced through biological systems. In particular, individual differences in the tuning of biological systems that respond to social threats may motivate individuals to seek out differently structured social environments. Drawing on a sample of adolescent males who underwent fMRI brain imaging (n = 74) and contributed Facebook data, we examined whether biological responses to a common scenario - being excluded from an activity with peers - was associated with their social network structure. We find that neural responses during social exclusion in a priori hypothesized "social pain" regions of the brain (dACC, AI, subACC) are associated with the density and transitivity of core friendship networks. These findings suggest that neural reactivity to exclusion may be one factor that underlies network "safety". More broadly, the study shows the potential of linking social cognitive tendencies to social structural properties.

Indirectly connected: simple social differences can explain the causes and apparent consequences of complex social network positions

Animal societies are often structurally complex. How individuals are positioned within the wider social network (i.e. their indirect social connections) has been shown to be repeatable, heritable and related to key life-history variables. Yet, there remains a general lack of understanding surrounding how complex network positions arise, whether they indicate active multifaceted social decisions by individuals, and how natural selection could act on this variation. We use simulations to assess how variation in simple social association rules between individuals can determine their positions within emerging social networks. Our results show that metrics of individuals' indirect connections can be more strongly related to underlying simple social differences than metrics of their dyadic connections. External influences causing network noise (typical of animal social networks) generally inflated these differences. The findings demonstrate that relationships between complex network positions and other behaviours or fitness components do not provide sufficient evidence for the presence, or importance, of complex social behaviours, even if direct network metrics provide less explanatory power than indirect ones. Interestingly however, a plausible and straightforward heritable basis for complex network positions can arise from simple social differences, which in turn creates potential for selection to act on indirect connections.

Persuasion, Influence, and Value: Perspectives from Communication and Social Neuroscience

Opportunities to persuade and be persuaded are ubiquitous. What determines whether influence spreads and takes hold? This review provides an overview of evidence for the central role of subjective valuation in persuasion and social influence for both propagators and receivers of influence. We first review evidence that decisions to communicate information are determined by the subjective value a communicator expects to gain from sharing. We next review evidence that the effects of social influence and persuasion on receivers, in turn, arise from changes in the receiver's subjective valuation of objects, ideas, and behaviors. We then review evidence that self-related and social considerations are two key inputs to the value calculation in both communicators and receivers. Finally, we highlight biological coupling between communicators and receivers as a mechanism through which perceptions of value can be transmitted.

Brain and Social Networks: Fundamental Building Blocks of Human Experience

How do brains shape social networks, and how do social ties shape the brain? Social networks are complex webs by which ideas spread among people. Brains comprise webs by which information is processed and transmitted among neural units. While brain activity and structure offer biological mechanisms for human behaviors, social networks offer external inducers or modulators of those behaviors. Together, these two axes represent fundamental contributors to human experience. Integrating foundational knowledge from social and developmental psychology and sociology on how individuals function within dyads, groups, and societies with recent advances in network neuroscience can offer new insights into both domains. Here, we use the example of how ideas and behaviors spread to illustrate the potential of multilayer network models.

Brain connectivity dynamics during social interaction reflect social network structure

Social ties are crucial for humans. Disruption of ties through social exclusion has a marked effect on our thoughts and feelings; however, such effects can be tempered by broader social network resources. Here, we use fMRI data acquired from 80 male adolescents to investigate how social exclusion modulates functional connectivity within and across brain networks involved in social pain and understanding the mental states of others (i.e., mentalizing). Furthermore, using objectively logged friendship network data, we examine how individual variability in brain reactivity to social exclusion relates to the density of participants' friendship networks, an important aspect of social network structure. We find increased connectivity within a set of regions previously identified as a mentalizing system during exclusion relative to inclusion. These results are consistent across the regions of interest as well as a whole-brain analysis. Next, examining how social network characteristics are associated with task-based connectivity dynamics, we find that participants who showed greater changes in connectivity within the mentalizing system when socially excluded by peers had less dense friendship networks. This work provides insight to understand how distributed brain systems respond to social and emotional challenges and how such brain dynamics might vary based on broader social network characteristics.