Abstract

Background: Early childhood screen exposure has increased rapidly, raising concerns about potential effects on cognitive, language, and early executive function development. The aim of this study was to provide a systematic synthesis of the evidence on screen exposure in children aged 2–5 years, addressing the fragmentation in existing research.

Methods: A systematic search was performed in PubMed, Web of Science, and Scopus for studies published between 2000 and 2025, following PRISMA guidelines. Boolean keyword combinations included terms relating to screen time, digital media exposure, cognition, language development, and executive functions. Eligible studies were observational or interventional, reported quantitative measures of screen exposure, and assessed cognitive, language, or executive outcomes in children aged 2–5 years. Exclusion criteria included unclear exposure definitions, samples outside the target age range, qualitative designs, reviews, and gray literature. Data extraction covered exposure metrics, outcome measures, effect estimates, and methodological quality.

Results: The search yielded 1,105 records; 860 remained after duplicate removal; 115 underwent full-text screening; and 43 studies met inclusion criteria. Across the evidence base, higher daily screen time was consistently associated with lower language scores, modest reductions in cognitive performance, and decreased inhibitory control and working memory. Exposure exceeding 2–3 hours/day showed the strongest links to developmental delays. Studies assessing media context found passive viewing and background television to be more detrimental than co-viewing or educational content. Considerable heterogeneity in exposure and outcome measurement limited cross-study comparability.

Conclusions: Early screen exposure is unlikely to be neutral; dose and context matter. Future research should use preregistered longitudinal cohorts with standardized testing and objective exposure metrics (device logs/background TV) plus content/co-viewing coding, analyzed with threshold and causal methods (propensity, fixed-effects, within-family). Pragmatic trials should test reducing passive/background viewing and promoting co-viewing with high-quality educational/interactive media, with objective adherence.