Intimacy-driven conformity: A between- and within-person perspective on friendship quality and adolescent susceptibility to peer norms about alcohol.

Background: Friendships become increasingly influential in early adolescence, leading to a greater impact of friends' norms on behavior. However, not all youth conform to norms, suggesting other factors may shape this influence. One such factor is friendship quality, which may shape adolescents' motivation to adopt peer norms, especially when those norms come from close, supportive friendships. This study examined how perceptions of friends' alcohol use and approval predict adolescents' intentions to drink, and whether friendship quality moderates these effects while disaggregating between- and within-person effects using a multilevel, longitudinal design.

Methods: Hierarchical linear modeling with a community sample of adolescents (n = 387) across 3 years tested hypotheses by distinguishing within- and between-person associations, capturing both the dynamic nature of friendships and how shifts in perceived norms influence alcohol intentions over time, as well as adolescents' broader tendency to affiliate with peers who approve of or engage in alcohol use. Interactions were tested using cross-product terms.

Results: Results partially supported hypotheses suggesting that friendship quality impacted susceptibility to peer norms regarding perceptions of friends' approval (β = 0.28, p = 0.026) but not use (β = 0.22, p = 0.214). The models supported the decomposition of between- and within-person effects, as both friends' approval (between-person: β = 0.58, p < 0.001; within-person: β = 0.37, p < 0.001) and use (between-person: β = 0.61, p < 0.001; within-person: β = 0.29, p < 0.001) were positively associated with future intentions to drink.

Conclusions: Taken together, results suggest that high-quality friendships amplified the influence of perceived friends' approval on alcohol intentions at the between-person level, but not for perceptions of use. Adolescents may prioritize maintaining their friendships; in turn, they adjust their beliefs and perceptions to preserve these relationships. Furthermore, perceptions of friends' alcohol norms operated similarly at the between- and within-level.