Elizabeth Carla de Almeida Hirata

• The primary aim of this dissertation is to promote the knowledge about how social interactions can impact on and be impacted by the food intake of others. To this end, based on the normative framework on eating behaviors, this work investigates whether self-construals and self-esteem moderate social modeling and matching effects. Next, it examines whether intake matching fosters affiliation between people. Finally, it explores how social influence affects food intake, after people are left alone. The first two experiments, conducted in Brazil and in Germany, explored the possible moderating role of self-construals on informational intake norms. In both countries, participants modeled the informational intake norms. However, self-construals did not impact their tendency to model. Additionally, an effect size comparison showed cultural similarity in the extent Brazilian and German females modeled. The next study used a dyadic setting to examine whether matching intake would increase perceptions of mutual closeness. Participants matched their food intake, and also had similar evaluations of closeness and likability of each other. However, intake matching was unrelated to their evaluations. Besides, trait self-esteem was unrelated to matching in this study. The last experiment tested whether a non-eating observer could affect people’s food intake even when they were left alone. In the baseline period, all participants were accompanied by a non-eating confederate, while given access to food. Next, half of them continued with the confederate and the other half was left alone. Food intake increased among those who were left alone, but not with those who continued with the confederate. These present thesis provides important findings, by reinforcing the importance of modeling and matching effects, as well as revealing that social influences might impact intake even when we are alone.