Media exposure is often cited as a causal factor in the development of body dissatisfaction, or negative thoughts and feelings toward the body (Grogan, 2017; Thompson, Heinberg, Atlabe, & Tantleff-Dunn, 1999). While eating disorders most commonly emerge during late adolescence (18-21 years), risk factors that predict the later onset of eating disorders emerge much earlier and escalate during adolescence (13-16 years; Hudson, Hiripi, Pope, & Kessler, 2007; Rhode, Stice, & Marti, 2016). Overall, links between exposure to traditional forms of mainstream media (e.g. television and magazines), body dissatisfaction, and eating disorder symptomatology are well- established in the literature, with robust findings based on correlational, longitudinal, and experimental research (e.g. Grabe, Ward, & Hyde, 2008; Hargreaves & Tiggemann, 2003; Harrison & Heffner, 2006). However, social media (e.g. Facebook, Instagram, TikTok) now dominate the media diets of adolescents, and differ from traditional media in ways that may exacerbate the association between media exposure and body-related outcomes. Previous research suggests that social comparison and self-objectification may represent two psychological mechanisms by which media exposure can impact body dissatisfaction (Festinger, 1954; Fredrickson & Roberts, 1997). The first study was a between-subjects experimental protocol completed by ninth grade students (N = 147; 75 boys, 69 girls, 3 did not report gender; Mage = 14.54, SDage = .57) and a comparison sample of college students (N = 581; 144 men, 448 women, 9 did not report gender; Mage = 19.39, SDage = 1.72) designed to examine the impact of social comparison and self-objectification on body dissatisfaction. Participants completed either a control task or an experimental manipulation that prompted either self-objectification or both self- objectification and social comparison. Results of this study indicated partial support for hypotheses, specifically that adolescents are particularly sensitive to social comparison processes compared to college students. The second study explored the impact of social media use on body dissatisfaction and eating disorder symptomatology among the same sample of adolescents. This study also explored the role of individual difference characteristics (i.e. self-perceived gender typicality and self-monitoring) in the relationship between social media use and body-related outcomes (Egan & Perry, 2001; Leaper & Brown, 2008; Snyder, 1986; Graziano, Leone, Musser, & Lautenschlager, 1987). Results indicated that higher emotional investment in technology predicted higher eating disorder symptomatology among girls, especially for girls who felt less typical for their gender than their peers. Results also indicated that higher self-monitoring, or greater sensitivity to the opinions of peers, was associated with higher body dissatisfaction and eating disorder symptomatology among both girls and boys. Taken together, the results of these studies suggest that emotional investment in experiences online may contribute to the development of body dissatisfaction and eating disorder symptomatology among adolescents, who are already at a greater risk of experiencing negative body image
