Classroom Popularity Hierarchy Predicts Prosocial and Aggressive Popularity Norms Across the School Year.

This study examined the coevolution of prosocial and aggressive popularity norms with popularity hierarchy (asymmetries in students' popularity). Cross-lagged-panel analyses were conducted on 2,843 secondary school students (Nclassrooms  = 120; Mage  = 13.18; 51.3% girls). Popularity hierarchy predicted relative change in popularity norms over time, but not vice versa. Specifically, classrooms with few highly popular and many unpopular students increased in aggressive popularity norms at the beginning of the school year and decreased in prosocial popularity norms at the end of the year. Also, strong within-classroom asymmetries in popularity predicted relatively higher aggressive popularity norms. These findings may indicate that hierarchical contexts elicit competition for popularity, with high aggression and low prosocial behavior being seen as valuable tools to achieve popularity.

Adolescents' Friendships, Academic Achievement, and Risk Behaviors: Same-Behavior and Cross-Behavior Selection and Influence Processes.

This study examined to what extent adolescents' and their friends' risk behaviors (i.e., delinquency and alcohol use) hinder or promote their academic achievement (grade point average [GPA]), and vice versa. Longitudinal data were used (N = 1,219 seventh- to ninth-grade adolescents; Mage  = 13.69). Results showed that risk behaviors negatively affected adolescents' GPA, whereas GPA protected against engaging in risk behaviors. Moreover, adolescents tended to select friends who have similar behaviors and friends' behaviors became more similar over time (same-behavior selection and influence). Furthermore, although same-behavior effects seemed to dominate, evidence was found for some cross-behavior selection effects and a tendency in seventh grade for cross-behavior influence effects. Concluding, it is important to investigate the interplay between different behaviors with longitudinal social network analysis.

The Norms of Popular Peers Moderate Friendship Dynamics of Adolescent Aggression.

This study examined whether peer norms for aggression within the classroom impact friendship selection, maintenance, and socialization processes related to aggression across the 1st year of secondary school (N = 1,134 students from 51 classes, Mage  = 12.66). As hypothesized, longitudinal social network analyses indicated that friendship selection and influence processes related to aggression depended on the popularity norm within the classroom (i.e., the class-level association between popularity and aggression) rather than the descriptive norm (aggregated average of aggressive behavior). Hence, only in classes where the valence of aggression is high (because it is positively associated with popularity), adolescents tend to select their friends based on similarity in aggression and adopt the aggressive behavior of their friends.

Predicting life-time and regular cannabis use during adolescence; the roles of temperament and peer substance use: the TRAILS study.

AIMS: The aim of the present study was to determine the mediating role of affiliation with cannabis-using peers in the pathways from various dimensions of temperament to life-time cannabis use, and to determine if these associations also contributed to the development of regular cannabis use. METHODS: Objectives were studied using data from 1300 participants of the Tracking Adolescents' Individual Lives Survey (TRAILS), a large, general population study of Dutch adolescents. We used parent-reports on the Early Adolescent Temperament Questionnaire to assess the dimensions of high-intensity pleasure, shyness, fearfulness, frustration and effortful control at age 10-12 years. By means of self-reports, life-time and regular cannabis use were determined at age 15-18 years, and proportion of substance-using peers was determined at ages 12-15 and 15-18 years. Models were adjusted for age, sex, intelligence and parental cannabis use. RESULTS: High-intensity pleasure [odds ratio (OR) = 1.09, 95% confidence interval (CI) = 1.05-1.13] and effortful control (OR = 0.92, 95% CI = 0.89-0.96) affected the risk for life-time cannabis use through their influence on affiliation with cannabis-using peers. Shyness affected this risk independently from peer cannabis use. Only the pathway from effortful control was associated additionally with the development of regular cannabis use (OR = 0.93, 95% CI = 0.89-0.98). CONCLUSIONS: Peer cannabis use and, to a lesser extent, certain temperamental characteristics affect an adolescent's risk of cannabis use, and should be considered in prevention programmes. We recommend future research to focus upon factors that potentially modify the association between temperament, affiliation with cannabis-using peers and cannabis use.