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Concept: Friendship


Human social networks are overwhelmingly homophilous: individuals tend to befriend others who are similar to them in terms of a range of physical attributes (e.g., age, gender). Do similarities among friends reflect deeper similarities in how we perceive, interpret, and respond to the world? To test whether friendship, and more generally, social network proximity, is associated with increased similarity of real-time mental responding, we used functional magnetic resonance imaging to scan subjects' brains during free viewing of naturalistic movies. Here we show evidence for neural homophily: neural responses when viewing audiovisual movies are exceptionally similar among friends, and that similarity decreases with increasing distance in a real-world social network. These results suggest that we are exceptionally similar to our friends in how we perceive and respond to the world around us, which has implications for interpersonal influence and attraction.

Concepts: Psychology, Brain, Sociology, Magnetic resonance imaging, Similarity, Friendship, Social network


Persuasion is at the core of norm creation, emergence of collective action, and solutions to ‘tragedy of the commons’ problems. In this paper, we show that the directionality of friendship ties affect the extent to which individuals can influence the behavior of each other. Moreover, we find that people are typically poor at perceiving the directionality of their friendship ties and that this can significantly limit their ability to engage in cooperative arrangements. This could lead to failures in establishing compatible norms, acting together, finding compromise solutions, and persuading others to act. We then suggest strategies to overcome this limitation by using two topological characteristics of the perceived friendship network. The findings of this paper have significant consequences for designing interventions that seek to harness social influence for collective action.

Concepts: Psychology, Sociology, Perception, Social psychology, Philosophy of perception, Friendship, Social influence, Persuasion


Weight-based stigma compromises the social networks of overweight children. To date, research on the position of overweight children in their peer network has focused only on friendship relations, and not on negative relationship dimensions. This study examined how overweight was associated with relations of friendship and dislike (antipathies) in the peer group. Exponential random graph models (ERGM) were used to examine friendship and antipathy relations among overweight children and their classmates, using a sub-sample from the TRacking Adolescents' Individual Lives Survey (N = 504, M age 11.4). Findings showed that overweight children were less likely to receive friendship nominations, and were more likely to receive dislike nominations. Overweight children were also more likely than their non-overweight peers to nominate classmates that they disliked. Together, the results indicate that positive and negative peer relations are impacted by children’s weight status, and are relevant to addressing the social marginalization of overweight children.

Concepts: Sociology, Adolescence, Graph theory, Peer group, Friendship, Peer-to-peer, Network theory, Random graph


Low levels of physical activity and increased participation in sedentary leisure-time activities are two important obesity-risk behaviors that impact the health of today’s youth. Friend’s health behaviors have been shown to influence individual health behaviors; however, current evidence on the specific role of friendship networks in relation to levels of physical activity and sedentary behavior is limited. The purpose of this review was to summarize evidence on friendship networks and both physical activity and sedentary behavior among children and adolescents.

Concepts: Sociology, Activity, Behavior, Human behavior, Friendship, Laelius de Amicitia


We propose the savanna theory of happiness, which suggests that it is not only the current consequences of a given situation but also its ancestral consequences that affect individuals' life satisfaction and explains why such influences of ancestral consequences might interact with intelligence. We choose two varied factors that characterize basic differences between ancestral and modern life - population density and frequency of socialization with friends - as empirical test cases. As predicted by the theory, population density is negatively, and frequency of socialization with friends is positively, associated with life satisfaction. More importantly, the main associations of life satisfaction with population density and socialization with friends significantly interact with intelligence, and, in the latter case, the main association is reversed among the extremely intelligent. More intelligent individuals experience lower life satisfaction with more frequent socialization with friends. This study highlights the utility of incorporating evolutionary perspectives in the study of subjective well-being.

Concepts: Scientific method, Life, Sociology, Science, Population density, Empiricism, Learning, Friendship


Middle adolescents' close friendship strength and the degree to which their broader peer group expressed a preference to affiliate with them were examined as predictors of relative change in depressive symptoms, self-worth, and social anxiety symptoms from ages 15 to 25 using multimethod, longitudinal data from 169 adolescents. Close friendship strength in midadolescence predicted relative increases in self-worth and decreases in anxiety and depressive symptoms by early adulthood. Affiliation preference by the broader peer group, in contrast, predicted higher social anxiety by early adulthood. Results are interpreted as suggesting that adolescents who prioritize forming close friendships are better situated to manage key social developmental tasks going forward than adolescents who prioritize attaining preference with many others in their peer milieu.

Concepts: Anxiety, Psychology, Sociology, Adolescence, Adult, Friendship, Adulthood, 2000 albums


Adolescents' emotional reactivity in family, close friendships, and romantic relationships was examined in a community-based sample of 416 two-parent families. Six waves of annual data were analyzed using structural equation modeling. Emotional reactivity to interparental conflict during early adolescence was associated prospectively with adolescents' reactivity to conflict in friendships and romantic relationships during middle adolescence. Close friendship reactivity partially explained the prospective association between reactivity to interparental conflict and romantic relationship reactivity. The association between perceived emotional reactivity and relationship conflict was stronger for girls than boys. Results have important developmental implications regarding adolescents' emotional reactivity across salient interpersonal contexts during adolescence. (PsycINFO Database Record © 2013 APA, all rights reserved).

Concepts: Family, Psychology, Interpersonal relationship, All rights reserved, Love, Friendship, Intimate relationship, Romance


Research has shown that the teacher-student interpersonal relationship (TSIR) is important for student motivation. Although TSIR has received a growing interest, there are only few studies that focus on changes and links between TSIR and student academic motivation in a longitudinal fashion in non-Western contexts.

Concepts: Psychology, Interpersonal relationship, Love, Friendship, Interpersonal relationships


The association between perceived friendship quality (FQ) and social information processing (SIP) was examined in three groups of children and their close friends aged 7-12 years: 16 anxiety disordered children with social phobia (SP); 12 anxiety disordered children without SP (No-SP); and 32 nonclinical children. Positive and negative FQ positively associated with target children’s positive and negative responding on a vignette measure of SIP. SP children reported lower positive SIP than No-SP but not nonclinical children; and this was the only group difference in SIP. Target children and their friends were similar in negative but not positive SIP. Following discussion about the vignette with a close friend, all target children increased in positive SIP; negative SIP did not change. Lower FQ and a more socially anxious friend predicted higher negative target child SIP postdiscussion. Close friendships play an important role in the SIP of both clinical and nonclinical children.

Concepts: Psychology, Sociology, Interpersonal relationship, Fear, Fight-or-flight response, Love, Friendship, Panic attack


The identification and recruitment of trustworthy partners represents an important adaptive challenge for any species that relies heavily on cooperation [1, 2]. From an evolutionary perspective, trust is difficult to account for as it involves, by definition, a risk of non-reciprocation and defection by cheaters [3, 4]. One solution for this problem is to form close emotional bonds, i.e., friendships, which enable trust even in contexts where cheating would be profitable [5]. Little is known about the evolutionary origins of the human tendency to form close social bonds to overcome the trust problem. Studying chimpanzees (Pan troglodytes), one of our closest living relatives, is one way of identifying these origins. While a growing body of research indicates that at least some of the properties of close human relationships find parallels in the social bonds of chimpanzees [6-10] and that chimpanzees extend favors preferentially toward selected individuals [11-14], it is unclear whether such interactions are based on trust. To fill this gap in knowledge, we observed the social interactions of a group of chimpanzees and established dyadic friendship relations. We then presented chimpanzees with a modified, non-verbal version of the human trust game and found that chimpanzees trust their friends significantly more frequently than their non-friends. These results suggest that trust within closely bonded dyads is not unique to humans but rather has its evolutionary roots in the social relationships of our closest primate relatives.

Concepts: Human, Sociology, Interpersonal relationship, Hominidae, Friendship, Evolutionary psychology, Human evolution, Common Chimpanzee