Screen time in context: Toward a theoretical model of digital engagement across the lifespan

The concept of "screen time" dominates research, policy, and public discourse on digital technology use yet remains conceptually imprecise and methodologically inadequate. Collapsing diverse digital activities into a single duration-based metric oversimplifies the complexity of digital engagement and obscures how developmental context shapes its effects. In this article, we examine the limitations of time-based measures and propose an ecosystemic, context-sensitive framework grounded in Bronfenbrenner's bioecological theory. We elaborate the concept of "virtual microsystems" to capture the layered physical and digital environments in which interactions occur across the lifespan. Drawing on empirical findings from early childhood through older adulthood, we demonstrate that heterogeneity in digital engagement, including mode of engagement, purpose of use, timing and context of use, content structure, and emotional valence, influences cognitive and mental health outcomes in developmentally distinct ways. By reframing digital engagement through an ecological lens, we identify clear directions for developing multidimensional assessment tools and flexible policy guidelines that reflect the diversity, quality, and context of digital experiences. (PsycInfo Database Record (c) 2026 APA, all rights reserved).