Introduction to the special section on social norms and behavioral development

This introduction outlines the goals for the special section on social norms and behavioral development. The study of social norms has attracted much interest in peer relations research, and has turned attention to group-level processes, often defined based on the classroom, which create and sustain shared meanings that impact adolescent behavioral and social adjustment. Norms can be differentiated in three ways. First, prescriptive or injunctive norms can be distinguished from descriptive norms. Second, a distinction can be made between what is salient for all classmates or for a subgroup of norm setters, in particular popular peers. Third, social norms can be distinguished from perceived norms. The contributions to this special section invite debate on the future of research on norms, and suggest numerous avenues for further research, with hopes that an understanding of how social norms affect social development will better inform peer relations research as well as norm-based interventions.

The goal of this special section is to give an overview of studies of social norms and behavioral development. Norms reflect the consensus on what is considered appropriate and acceptable behavior in a given setting. Norms are social facts that originate from individuals' attitudes and behaviors, but in turn affect individual attitudes, decisions, and behaviors. Thus, norms emerge from collective consensus about what is appropriate or typical in given social circumstances, but they also shape, constrain, and redirect behavior.

Overview of the Special Section
Classroom norms can be defined in various ways (Veenstra & Lodder, 2022). A first distinction can be made between prescriptive or injunctive norms, referring to students' perceptions of how one should behave, and descriptive norms, referring to students' behaviors. A second distinction can be made between what is salient for all classmates or for a subgroup of norm setters, in particular popular peers. A third distinction can be made between social norms, measured at the meso-or macro-level, and perceived norms, measured at the micro-level. This overview is structured according to these distinctive measures of social norms.

Prescriptive Norms
The aim of a longitudinal study among Colombian adolescents was to examine whether aggression results in subsequent victimization (Bass et al., 2022). This multilevel study expanded upon the person-group dissimilarity or social "misfit" model (Wright et al., 1986), and addressed the effects of different types of peer group norms on the group sanction when individuals deviated from the norm. The study used a multi-method design, combining self-reports with peer-nomination procedures. No support was found for a gender-based misfit effect of aggression (based on same-sex classroom prescriptive norms). Evidence was found for the peer group norm misfit effect for both the proximal and distal prescriptive norms. The social sanction of aggression through subsequent victimization varied based on the appropriateness of the behavior among friends or classmates. These effects differed by type of aggression.

Descriptive Norms
A strength of a descriptive norm study in this special section was its focus on special education classrooms (De Swart et al., 2022). This multilevel study also used the person-group dissimilarity model (Wright et al., 1986), and examined, using cross-sectional analyses at four time points, the moderating effect of the descriptive classroom norm for problem behaviors on the association between individual problem behaviors (referring to externalizing, internalizing, and attention-hyperactivity problems) and social status (referring to acceptance, rejection, and perceived popularity). A multi-method design was employed, combining teacher reports with peer nominations, to address a gap in the literature regarding our understanding of how social status in special education classrooms may be influenced by behavioral norms. The findings provide some evidence that associations between the problem behaviors measured and social status differ as a function of behavioral norms in special education classrooms.

Norm Salience
The aim of another multilevel study that used the person-group dissimilarity model was to examine the role of norms in friendship influence related to physical, relational, and general aggression (Correia et al., 2022). In this longitudinal multilevel study, the classroom norm was defined as the degree to which the three forms of aggression relate to social preference. This norm salience was calculated separately for girls and boys. In classrooms with a positive link between relational aggression and social preference, it was more likely that friends' relational aggression would predict increases in girls' relational aggression, especially for highly aggressive girls. These findings suggest that highly relationally aggressive girls may possess skills allowing them to adapt to the social context in which they and their friends interact. In contrast, the influence of male friends' general aggression was larger when norm salience was neutral or unfavorable, suggesting that boys who affiliate with aggressive friends may be more susceptible to aggressive friends' influence in general, and especially in the context of potential peer rejection. No moderating effect of norm salience was found for friends' influence on physical aggression socialization. These findings suggest that interventions aimed at changing the norm salience for aggression may only be effective in specific subgroups of aggressive youth.
Another norm salience study in this special section examined the associations between peer status and victim-oriented as well as bully-oriented defending (Garandeau et al., 2022). In this cross-sectional multilevel study, the classroom norm was defined as the degree to which bullying relates to perceived popularity or likeability. The findings show that popularity was more strongly associated with bully-oriented defending in classrooms in which bullies were unpopular than in classrooms in which bullies were popular. In classrooms where bullies were more rejected, both types of defending were more prevalent, and the positive associations of likeability and popularity with victim-oriented defending were stronger.
The third norm salience study examined the link between relational victimization and the development of risk-taking behavior (Tieskens et al., 2022). A multi-method design was employed, combining teacher reports, peer nominations, and an experimental task. In this longitudinal multilevel study, the classroom norm was defined as the degree to which risk-taking behavior relates to social preference. The findings indicate that when the norm salience was favorable toward risk-taking behavior, victims tended to decline taking part in risk-taking behavior, whereas when the norm salience was unfavorable toward risktaking behavior, victims showed norm-defying behavior, in the sense that they acted contrary to the norms and increased participation in risk-taking behavior (Tieskens et al., 2022). An important question in this regard is whether victims are indeed "motivated" to engage in behavior that contradicts the norm and seek inclusion with classmates with a lower social status (Rudolph et al., 2014), or, alternatively, lack the social skills to understand what is normal in the classroom (in this special section: De Swart et al., 2022). Victims who lack social skills may try to fit in wrongly by acting in a manner that they think is cool but is not. A way to test this alternative explanation is by controlling for social skills. Furthermore, some students may deliberately choose not to adhere to social norms, if these stray too far from their personal convictions.

Descriptive Norms and Norm Salience
A cross-sectional social network study in this special section examined whether classroom norms played a role in the link between liking and defending (Rambaran et al., 2022). Defending is more likely for peers who students like or are liked by, and less likely for peers who students dislike or are disliked by. In line with the idea of power imbalance, it was expected that these effects would be weaker in classrooms where bullies hold more power (i.e., where the popularity norm is stronger), as the power of popular bullies may be stronger than the individual like or dislike relationships in a group. This study did not find consistent evidence that bullying norms in a group moderate these links.

Perceived Norms
The aim of a longitudinal social network study among South Korean children was to examine the moderating role of perceived bullying norms on friendship selection and influence processes related to bullying and victimization (Shin, 2022). The findings indicate that friendship selection and influence processes were stronger in classrooms where bullying behavior was more normative. When adolescents perceived bullying norms to be positive, bullying behaviors were more likely to be used as a friendship selection criterion and adolescents who bullied others more had a higher tendency to select high-bullying peers as friends. In addition, as adolescents perceived higher bullying norms, friendship influence on bullying and victimization was magnified. Anticipating positive consequences of bullying, bullies seemed to be more likely to adopt the bullying behavior of their high-bullying friends and engage in bullying even more frequently. Accordingly, when adolescents perceived bullying norms as positive, victimization experiences were more severe and friendship influence on victimization was stronger.

Norm Misperception
The goals of an experimental study were to examine, on the one hand, norm misperception of bullying attitudes and, on the other hand, whether a targeted brief intervention could reduce norm misperception, and possibly influence personal anti-bullying attitudes (Dillon & Lochman, 2022). The findings show that perceived peer attitudes toward bullying were more positive than actual group norms. Furthermore, it was shown that providing personalized feedback about the discrepancy between perceived group norms and actual group norms resulted in changes in perceived group norms regarding bullying, but not in personal attitudes toward bullying.

Beyond the Special Section
The closing essay conceptualizes how classroom norms may explain children's decisions to defend others or refrain from defending (Veenstra & Lodder, 2022). Norm conformity, pluralistic ignorance, and power balance are formulated as potential underlying mechanisms for the relation between classroom social norms and the level of defending. Future research is needed to examine whether these three mechanisms mediate the link between social norms and behavioral development. Examination of how social norms influence behavior is also important for the improvement of peer-led interventions (Veenstra & Laninga-Wijnen, 2022).
The studies presented in this special section measured social norms in various ways (see for an overview of common types of classroom norms: Veenstra & Lodder, 2022). Research suggests that behavior is mostly driven by what popular classmates do. For that reason, a norm based on what is salient among popular peers may be preferred (Laninga-Wijnen et al., 2017;Velásquez et al., 2021). More research is also needed on the significance of gender-specific or common classroom norms as well as on proximal and distal norms. A study in this special section provides evidence that proximal peer group norms, based on the norms of friends, were more powerful than distal peer group norms, based on the norms of classmates (Bass et al., 2022). The closing essay also points to the importance of examining competing norms, developmental effects, the impact of teachers on social norms, and the impact of personal norms (Veenstra & Lodder, 2022).

Conclusion
The study of social norms has attracted much interest in peer relations research, and has turned attention to group-level processes, often defined based on the classroom, which create and sustain shared meanings that impact adolescent behavioral and social adjustment. The contributions to this special section invite debate on the future of research on norms, and suggest numerous avenues for further research, with hopes that an understanding of how social norms affect social development will better inform peer relations research as well as norm-based interventions.