Abstract
The formation and maintenance of friendship closeness is an important developmental task in adolescence. To obtain insight in real-time processes that may underly the development of friendship closeness in middle adolescence, this preregistered experience sampling study [ESM] investigated the effects of social media use on friendship closeness. The study was conducted among 387 adolescents (54% girls; Mage = 14.11 years; 96% Dutch) from different educational tracks (44% lower prevocational secondary education, 31% intermediate general secondary education, 26% academic preparatory education). Adolescents reported six times per day for 3 weeks on their Instagram, WhatsApp, and Snapchat use in the previous hour and their momentary experiences of friendship closeness (126 assessments; 34,930 observations). Multilevel analyses revealed positive between-person associations of friendship closeness with general WhatsApp use and Instagram use with close friends. In contrast, at the within-person level, we found small negative overall associations of general WhatsApp use and Instagram use (with and without close friends) with friendship closeness. However, there was large heterogeneity in the person-specific effect sizes of the within-person associations of social media use with friendship closeness. For example, person-specific effect sizes of the association of Instagram use with close friends with friendship closeness ranged from ß = -.745 to ß = .697. These results underline the importance of acknowledging person-specific effects in developmental and media effect theories.
