Maartje Boer

INTRODUCTION 19 1 should be studied in parallel with their SMU intensity, because this reveals the similarities or differences between the two SMU behaviors. Which Factors Influence the Association Between SMU Intensity and Wellbeing? Although distinguishing SMU intensity and SMU problems is an important step towards improving our understanding in the association between SMU and wellbeing, there are other factors that may affect the association that have received little empirical attention thus far. More specifically, it has been postulated that the effect of SMU intensity on wellbeing depends on the activity the adolescent engages in (Verduyn et al., 2017). According to this view, active SMU activities, such as posting messages, photos, or videos and chatting with or responding to others on social media, are beneficial to wellbeing, because it enhances adolescents’ social capital and sense of belonging. In contrast, passive SMU activities, such as scrolling through peers’ messages, photos, and videos on social media, may be detrimental to wellbeing, because these activities expose adolescents to idealized unrealistic self-presentations of others, which induce envy andupward social comparison (Verduyn et al., 2017). In addition, according to the Goldilocks hypothesis , the relationbetweenadolescents’ SMU intensity andwellbeing follows an inverted u-shape, whereby moderate use could be advantageous to adolescents’ wellbeing (Przybylski & Weinstein, 2017). Also, according to the differential susceptibility to media effects model , media effects differ across individuals, because they are contingent on, for example, dispositional characteristics (Valkenburg & Peter, 2013). Furthermore, the link between adolescents’ SMU intensity and wellbeing may depend on methodological considerations, namely whether within- or between-person associations are studied. While the former indicate whether changes in two behaviors within a person are associated, the latter denote whether differences in two behaviors between persons are associated. It is not uncommon that within- and between-person associations differ in effect size or even direction (Hamaker, 2012). Thus, not only does the association between adolescents’ SMU intensity andwellbeingmay depend onwhether SMUproblems are taken into account, it may also depend on the conceptualization of SMU intensity (i.e., active vs. passive), the (non)linearity of the association, individual differences, and