A Network Analysis of Online and Offline Social Influence Processes in relation to Adolescent Smoking and Alcohol Use

Smoking and alcohol use are both prominent risk behaviors among adolescents in the U.S. On average, about 20% of high school students smoke regularly and as many as 40% of adolescents in the 12th grade report using alcohol in the past 30 days. Peer influences during adolescence are a strong predictor of risk-taking in part due to more time spent with peers and the added value they place their relationships.;Recent increases in social media outlets have transformed traditional communication patterns and information exchange, as well as the dimensions of social influence. Social media include mobile phones and a multitude of online social networking sites, which are likely to accelerate the transmission of information and adoption of new ideas or behaviors.;This dissertation study addresses whether adolescents' use of these new technologies affect their risk behaviors and how these new modes of communication might play a role in shaping normative perceptions, intentions, and behavioral choices about smoking and alcohol use.;Study One takes a multivariate approach to assess the impact of several measures relating to adolescent use of social network sites (SNS). Results demonstrated that SNSs differed in function and effects on adolescent risk behaviors. While no specific effects were attributed to the use of any specific SNS, the collective display of risky content by friends was positively associated with higher levels of smoking and alcohol use.;As an extension to the findings from the first paper, Study Two is based on a structural approach to examine the specific pathways of influence using a cognitive-behavioral framework to test whether social norms and behavioral intentions mediated the effects between social influences (in-person and digital) on behavior. A comparison of the relative correlations between in-person and digital risk exposures revealed that having friends who smoke or use alcohol and having friends who post content about these risk-behaviors online were both positively associated with intentions and longitudinally associated with behavior.;Study Three takes an in-depth longitudinal approach to examine whether associations between social influences and risk behaviors were attributed to actual influences due to behaviors exhibited by friends, or whether the association was attributed to friendship selection. Stochastic actor-based (SAB) modeling was followed by meta-analyses of the five school-level networks. Findings indicated that friendship selection effects were stronger than peer influence effects for both smoking and alcohol use, while influence effects were comparatively more prominent for alcohol use. In terms of social media effects, adolescent friendships were formed based on similar use of SNSs Facebook and Myspace and exposure to friends' risky online content contributed to increases in drinking and smoking.;In sum, the three studies using three different statistical methodologies, may be considered a "first look" at the interplay between online social networks, traditional in-person peer friendship networks, and their collective effects on adolescent smoking and alcohol use.