Esther Mertens

| 95 Classmate Influence in Intervention of mutuality, peers listen and respond appropriately to each other, are genuinely interested in one another, and express affection towards each other (Piehler & Dishion, 2007). Although dyadic mutuality is related to positive (e.g., satisfaction, intimacy) and negative aspects (e.g., conflict, dissatisfaction) of friendship, it is not the same since dyadic mutuality can be low within some friendships. It is therefore important to not only focus on a specific type of relationship, but also on the quality of this relation (Berndt, 2002). Dyadic mutuality can be used to describe a variety of relations, such as friendships or parent-child relationships, and represents the variation in quality among these relations (Piehler & Dishion, 2007). In the current study, we used dyadic mutuality to describe the variation in quality of relations between classmates. Given that there are various relations between classmates (e.g., (un)reciprocal friendships, popularity, conflictual relations; Juvonen & Ho, 2008), dyadic mutuality is eminently suited to examine the extent to which adolescents are affect by peer influence in the class. Berndt (2002) theorizes that adolescents are more strongly influenced by peers with whom they have high quality relations, which is supported by empirical research (e.g., Barry & Wentzel, 2006; Piehler & Dishion, 2007). Therefore, we hypothesized that students’ perception of the classroom peer context is more strongly influenced by classmates’ modeling and reinforcement in dyads with higher levels of mutuality. Current Study In order to fully capture the complexity of the classroom peer context, the current study focused on characteristics of all four levels of the peer context as described by Hinde (1987) and Rubin and colleagues (2006). The individual level refers to individual characteristics students bring into the interaction (e.g., comfort). The interaction level refers to daily dyadic interactions in which students are interdependent; a student’s behavior is both a response to and a stimulus for another student’s behavior (e.g., conflict). The relationship level refers to a succession of interactions embedded in long- term knowledge of each other and is therefore influenced by meanings, expectations, and emotions of students towards each other (e.g., dyadic mutuality). The group level refers to the patterns and characteristics of interactions and relationships in a group of individuals (e.g., a class) who reciprocally influence each other. This process forms norms and shared cultural conventions that indicate which type of relations and interactions are acceptable (e.g., cohesion, victimization). These four levels are intertwined and interact together. Students’ experiences with peers at one level have an influence on their experiences at the other levels. The present study adds to the literature in three ways. First, we assessed classmates’ influences and dyadic mutuality through observations within a randomized controlled trial of a universal intervention. Not only did the observations enable us to obtainmore objective measures of modeling, reinforcement, and dyadic mutuality than through students’ self-report, it also enabled us to examine change in students modeling and 5