Tracing 20 years of research on problematic use of the internet and social media: Theoretical models, assessment tools, and an agenda for future work.

Over the past two decades, there has been increasing interest in the impact of internet use and growing concern about whether problematic use of the internet (PUI) constitutes an addiction. Despite the growing number of studies investigating PUI and PUI subtypes, its conceptualization and inclusion in a classification system have not been possible yet. Several models aimed at inspiring clinical research and practice have proposed possible mechanisms involved in PUI and problematic use of social media, and multiple self-report instruments have been consequentially developed. The diversity of theoretical models and instruments currently hinders standardized assessment procedures across studies and, in turn, their comparability. The purpose of the present overview is to highlight the current conceptualization and assessment of both PUI and problematic use of social media, in order to critically discuss the existing fragmentation in the field and the need to achieve conceptual convergence. Two suggestions for future directions are also provided, i.e., define diagnostic criteria by bottom-up and top-down processes and develop a psychobiological hypothesis including the description of higher-order mechanisms involved in PUI and not other psychopathological conditions (e.g., the multiple available internet-related cues and outcomes that may lead to parallel forms of associative learning; probabilities of obtaining internet-related reinforcements; and intrinsic motivation processes).