Od and adolescence. Sullivan (1953) suggested that friendships change from being competitive to being intimate and mutually cooperative during the transition from childhood to adolescence (Sullivan, 1953). Several studies have confirmed this assertion, demonstrating an increase in cooperation, support and intimacy of friendships during this period (Berndt, 1982; Buhrmester, 1990). When outsiders intrude on a friendship in childhood, some children are especially vulnerable to conflict, tension and jealousy (Asher et al., 1998). Susceptibility to jealousy in such interactions is related to the child’s psychological AZD0156 biological activity well-being. Children with low self-worth are more likely to perceive intrusion into their friendships and tend to be jealous of such attempts, whereas children with high self-worth tend to endorse feeling less competitive when their friend engages in activities with others (Parker et al., 2005). As well, children and adolescents with low self-worth may show increased surveillance behavior, monitoring their friend’s actions, related to the jealousy that they feel in their friendships (Lavallee and Parker, 2009). Inflexibility in accepting a friend’s other peer relations and high rumination are associated with surveillance behavior and jealous emotions, all of which further contribute to conflict in the child’s friendship along with depressive symptoms and loneliness (Lavallee and Parker, 2009). This finding suggests that children prone to psychological distress may be more strongly engaged by social signals intimating an interpersonal threat to their friendships. Moreover, negative emotions that develop in response to violation of friendship expectations differ among boys and girls with girls being more sad and angry after transgressions in friendship (MacEvoy and Asher, 2012).Social exclusionSocial exclusion is common in human relationships across development (Eisenberger et al., 2003; Williams, 2007). In children, continued social exclusion among peer groups is associated with poor academic performance, dysregulated emotion, and loss of physical control (Nesdale and Flesser, 2001; Kim et al., 2005; Schwartz et al., 2008). Peer rejection has been implicated in the development of disruptive behavior problems (Dodge and Pettit, 2003), interpersonal difficulties (Downey et al., 1998), low self-esteem and increased levels of internalizing problems (anxiety and depression) (Deater-Deckard, 2001; Ladd, 2006). While the effects of peer rejection can be diverse, as a process, it tends to be stable in social groups and difficult for a child to overcome (Jiang and Cillessen, 2005). Continued social exclusion leads to increased need for belongingness in relationships as a physiological necessity. Williams et al. (2013) have proposed that individuals keep watch for experiences of social exclusion and acceptance via an adaptive social monitoring system. This AZD0156 web system tracks exclusion and acceptance and monitors future social interactions based on previous experiences. Individual differences in psychopathology, especially loneliness and low self-esteem, modify the functioning of the social monitoring system. When the need for belonging is high, biases develop in perceived socialinteractions as well as greater interpersonal sensitivity. For example, lonely people remember more information about interpersonal characteristics of rejection and are less accurate when interpreting non-verbal cues (Williams et al., 2013). Social exclusion research in.Od and adolescence. Sullivan (1953) suggested that friendships change from being competitive to being intimate and mutually cooperative during the transition from childhood to adolescence (Sullivan, 1953). Several studies have confirmed this assertion, demonstrating an increase in cooperation, support and intimacy of friendships during this period (Berndt, 1982; Buhrmester, 1990). When outsiders intrude on a friendship in childhood, some children are especially vulnerable to conflict, tension and jealousy (Asher et al., 1998). Susceptibility to jealousy in such interactions is related to the child’s psychological well-being. Children with low self-worth are more likely to perceive intrusion into their friendships and tend to be jealous of such attempts, whereas children with high self-worth tend to endorse feeling less competitive when their friend engages in activities with others (Parker et al., 2005). As well, children and adolescents with low self-worth may show increased surveillance behavior, monitoring their friend’s actions, related to the jealousy that they feel in their friendships (Lavallee and Parker, 2009). Inflexibility in accepting a friend’s other peer relations and high rumination are associated with surveillance behavior and jealous emotions, all of which further contribute to conflict in the child’s friendship along with depressive symptoms and loneliness (Lavallee and Parker, 2009). This finding suggests that children prone to psychological distress may be more strongly engaged by social signals intimating an interpersonal threat to their friendships. Moreover, negative emotions that develop in response to violation of friendship expectations differ among boys and girls with girls being more sad and angry after transgressions in friendship (MacEvoy and Asher, 2012).Social exclusionSocial exclusion is common in human relationships across development (Eisenberger et al., 2003; Williams, 2007). In children, continued social exclusion among peer groups is associated with poor academic performance, dysregulated emotion, and loss of physical control (Nesdale and Flesser, 2001; Kim et al., 2005; Schwartz et al., 2008). Peer rejection has been implicated in the development of disruptive behavior problems (Dodge and Pettit, 2003), interpersonal difficulties (Downey et al., 1998), low self-esteem and increased levels of internalizing problems (anxiety and depression) (Deater-Deckard, 2001; Ladd, 2006). While the effects of peer rejection can be diverse, as a process, it tends to be stable in social groups and difficult for a child to overcome (Jiang and Cillessen, 2005). Continued social exclusion leads to increased need for belongingness in relationships as a physiological necessity. Williams et al. (2013) have proposed that individuals keep watch for experiences of social exclusion and acceptance via an adaptive social monitoring system. This system tracks exclusion and acceptance and monitors future social interactions based on previous experiences. Individual differences in psychopathology, especially loneliness and low self-esteem, modify the functioning of the social monitoring system. When the need for belonging is high, biases develop in perceived socialinteractions as well as greater interpersonal sensitivity. For example, lonely people remember more information about interpersonal characteristics of rejection and are less accurate when interpreting non-verbal cues (Williams et al., 2013). Social exclusion research in.