Esther Mertens

94 | Chapter 5 for instance, antisocial behaviors (e.g., Hofmann & Müller, 2018), aggression, and depression (Memmott-Elison et al., 2020), but also to increases in adolescents’ prosocial behavior (Busching & Krahé, 2020), positive interpersonal interactions in the class (e.g., Telzer, Van Hoorn, Rogers, & Do, 2018), and prosocial goal pursuit (e.g., Barry & Wentzel, 2006). Thus, increases in classmates’ deviant modeling and reinforcement could negatively affect how students perceive the classroom peer context, whereas increases in classmates’ prosocial modeling and reinforcement could positively affect students’ perceptions of the classroom peer context. The first aim of the current study was to examine whether the effect of an intervention on the perceived classroom peer context was mediated by changes in classmates’ modeling and reinforcement. Based on the social learning theory and the empirical findings, it seems possible to positively stimulate students’ perception of the classroom peer context by addressing classmates’ modeling and reinforcement. An intervention that aims to improve the classroom peer context through changing classmates’ modeling and reinforcement is Rock and Water (R&W; Ykema, 2002, 2018). R&W is a universal school-based intervention during which modeling and reinforcement are explicitly discussed and practiced. For instance, students model in role-play how to set boundaries in a non-aggressive way and discuss how reinforcing behaviors of peers can influence future behaviors. During the lessons, the trainer functions as a prosocial role model, reinforces students’ prosocial behavior as well as students’ reinforcement of prosocial behavior, and discourages and rejects students’ deviant behavior. Communication is framed in the symbolic principles of ‘rock’, a firm position in which students are able to resist pressure from others, and ‘water’, a relaxed but alert position in which students are open to opinions, thoughts, and feelings of others. Students are encouraged to establish positive relations and have respect for each other. By setting negative consequences for deviant behaviors and by modeling and reinforcing alternative prosocial behaviors, R&W aims to enhance positive peer relations in the class. R&W has been found to be effective in improving resilience, positive identity formation, coping styles, self-regulation, and self-efficacy and in decreasing coercive strategies and verbal manipulation (De Graaf, De Haas, Zaagsma, &Wijssen, 2015; Ykema, Hartman, & Imms, 2006). We hypothesized that R&W would increase students’ positive perceptions of the peer context in the classroom by decreasing students’ deviant and increasing students’ prosocial modeling and reinforcement. Dyadic Mutuality Our second aimwas to examine whether the relation between changes in classmates’ modeling or reinforcement and the perceived classroompeer context was moderated by dyadic mutuality. Dyadic mutuality indicates the degree of responsiveness, reciprocity and understanding shared between individuals. In dyads with high levels