Fourth, research in the last decade has revealed important findings regarding specific behaviors that may be most susceptible to peer socialization effects. This notion first was suggested by Berndt (1979), who hypothesized that susceptibility to pressure depended on the social and legal value associated with the target behavior. Clasen and Brown (1985) later proposed a modified classification of peer influence, urging a conceptualization of the process in terms of activity type. A rich literature initiated before this decade indicated that antisocial and unhealthy behaviors are most vulnerable to contagion processes. Recent work has further delineated that certain stages of behavioral engagement (e.g., initiation of smoking behavior or cessation of alcohol and chewing tobacco use; Maxwell, 2002) may be particularly prone to peer influence. Further, research of this decade has suggested that influence may be more salient for some subtypes of behavior; for example, Ryan (2001) found that classmates influenced middle schoolers’ academic achievement and intrinsic motivation for school, but not their expected success in school or their beliefs about the importance of school. Espelage, Holt, and Henkel (2003) detected a significant effect of adolescents’ peer group on increases in bullying, but not fighting.
