Maartje Boer

THE COURSE OF PROBLEMATIC SMU 197 7 psychosocial characteristics and problematic SMU over time, they did not explore whether these factors predict distinct trajectories of problematic SMU. For example, low subjective wellbeing may underlie specific trajectories of problematic SMU, but not others. Furthermore, these studies typically focused on predictors of changes in problematic SMU, which do not allow for establishing predictors of persistent levels of problematic SMU. Current Study Socialmediaareubiquitous inthedaily livesof contemporaryadolescents and likely play a significant role in the individual development of particularly young adolescents. Such a context, where social media are omnipresent, may make some adolescents susceptible to developing problematic SMU, which are characterized by symptoms of addiction. Using four waves of longitudinal data with yearly time intervals among Dutch adolescents in early and middle adolescence ( M age = 12.511, SD age = 0.602 in the first wave), this study firstly aimed to explore how adolescents’ level of problematic SMU evolved over time. Based on prior studies on the development of various types of problems during adolescence, we expected to find a persistent low- and a high-risk trajectory, and at least one more variable trajectory of problematic SMU. To consolidate our suggestion that problematic SMU differs from the frequency of SMU and illuminate the similarities or differences between their trajectories, we investigated adolescents’ trajectories of problematic SMU in parallel with their trajectories of SMU frequency. The second aim was to investigate to what extent subjective wellbeing (life satisfaction and self-esteem), low self- control (attention deficit and impulsivity), and social competencies predicted the identified trajectories. Although research showed that these psychosocial characteristics are related with problematic SMU, their role in particular developments of problematic SMU remains unexplored. Therefore, we did not establish a priori expectations regarding their predictive role in specific trajectories. Thus, given the data-driven approach to identify trajectories of problematic SMU and its predictors, the design of the present study was considered exploratory.