Since the advent of SNS technologies, adolescents' use of these technologies has expanded and is now a primary way of communicating with and acquiring information about others in their social network. Overall, adolescents and young adults’ stated motivations for using SNSs are quite similar to more traditional forms of communication—to stay in touch with friends, make plans, get to know people better, and present oneself to others. We begin with a summary of theories that describe the role of SNSs in adolescents’ interpersonal relationships, as well as common methodologies used in this field of research thus far. Then, with the social changes that occur throughout adolescence as a backdrop, we address the ways in which SNSs intersect with key tasks of adolescent psychosocial development, specifically peer affiliation and friendship quality, as well as identity development. Evidence suggests that SNSs differentially relate to adolescents’ social connectivity and identity development, with sociability, self-esteem, and nature of SNS feedback as important potential moderators. We synthesize current findings, highlight unanswered questions, and recommend both methodological and theoretical directions for future research.

Is an attenuated physiological response to family conflict, seen in some youth exposed to early adversity, protective or problematic? A longitudinal study including 54 youth (average age 15.2) found that those with higher cumulative family aggression exposure showed lower cortisol output during a laboratory-based conflict discussion with their parents, and were less likely to show the normative pattern of increased cortisol reactivity to a discussion they rated as more conflictual. Family aggression interacted with cortisol reactivity in predicting youth adjustment: adolescents from more aggressive homes who were also more reactive to the discussion reported more post-traumatic stress symptoms and more antisocial behavior. These results suggest that attenuated reactivity may protect youth from the negative consequences associated with aggressive family environments.

Close college-age friendships provide differential opportunities for reinforcing dispositional tendencies and fostering accommodation or change. This finding was obtained from a crosssectional study of 66 pairs of same-sex college-age friends (58% female). Each pair of friends was extreme and either very similar or different with regard to extraversion-introversion. Interviews with each friend were analyzed for references to each other's role in various friendship domains, including the setting of the friendship and position with regard to chatting, disclosing, expressing opinions about peers, and energizing the friendship. Matched friends mutually reinforced each other's similar dispositional tendencies. Friends with contrasting personalities showed patterns of personality accommodation as well as complementary reinforcement. Implications are discussed for embedding reciprocal theories of personality development in close friendships. KeywordsExtraversion-introversion; reciprocal-interaction; friendship practices; mutual reinforcement; complementarity One person's experience of another person has a special quality, quite different from his perception of a piece of cheese…. It is marked by a recognition of mutuality…accompanied by an appreciation of the feelings of the other person and some willingness to adjust to them…. It is difficult to interpret any interpersonal proceeding without knowledge of the history of both personalities and a knowledge of their current thoughts and feelings. (Murray, 1951, pp. 438-440) Observational studies have long recognized that particular personalities produce a distinctive social press or force (Block, 1971;Funder, 1999;Murray, 1938). To date, the social force of personality has usually been observed unilaterally, with less attention to how the personality of the observer interacts with that of the observed. In addition, studies of the bilateral force of personalities have usually focused on strangers rather than people who have a long history of interacting with each other (Sadler & Woody, 2003;Thorne, 1987;Tracey, 2004). While observations of strangers can reveal the instantaneous press of personality, interviews with friends can reveal how they come to live with and potentially adjust to each other's dispositional similarities and differences. Accordingly, this unprecedented study explored how close friends who were extreme and either very similar or very different with regard to extraversion-introversion reportedly engaged in an array of friendship practices. InteractionsThe dynamic interaction of personality and environments has increasingly gained broad theoretical attention (e.g., Caspi & Roberts, 2001;Fleeson, 2004;Mischel & Shoda, 1998). A commonality among dynamic approaches is adherence to the generally accepted view that personality has both bio-genetic and psychosocial foundations. New, however, is an emphasis on examining trait processes (e.g., how a person manages to enthusiastically chat with strangers) in addition to outcomes (e.g., I like to talk w...

This study investigated links between interparental conflict appraisals (specifically threat and self-blame), sibling relationship quality (positive and negative dimensions), and anxiety in sibling pairs comprised of an adolescent and a younger sibling close in age. Sibling relationship quality was measured through behavioral observation. Links between self-blame and anxiety were moderated by sibling relationship quality. In older siblings, positive behavior with a sibling was associated with an attenuated relation between self-blame and anxiety. A paradoxical moderating effect was found for negative interactions; for both younger and older siblings, a relation between self-blame and anxiety was weakened in the presence of sibling negativity. Results offered support for theorized benefits of sibling relationship quality in helping early adolescents adjust to conflict between parents.