Screen viewing time from age 1 to 8 years and subsequent academic performance and working memory

Screen viewing time is associated with children's academic and cognitive outcomes, but longitudinal studies are scarce, hindering identification of the most sensitive age periods. We assessed the associations of single and cumulative average screen viewing time with academic performance and working memory.

In the Growing Up in Singapore Towards healthy Outcomes birth cohort, parents reported their child's screen viewing time at ages 1, 1.5, 2, 3, 6 and 8 years. At ages 9 and 10.5, trained psychologists assessed academic performance (Wechsler Individual Achievement Test-Third Edition) and working memory (Letter-Number Sequencing task; Wechsler Intelligence Scale for Children-Fifth Edition). Associations of single and cumulative average screen viewing time with psychological outcomes were examined by multivariable linear regression (N = 502 children).

Mean (standard deviation) screen viewing time ranged from 2.1 (2.0) hours/day at age 1 year, to 3.0 (2.2) hours/day at 8 years. In unadjusted models, higher screen viewing time from age 1 to 8 years was consistently associated with poorer academic performance at age 9 years and working memory at 10.5 years. After adjustment, effect sizes were reduced, but higher screen viewing time at ages 1 year [β = - 1.47, 95% confidence interval (CI): - 2.37 to - 0.57 standard points per additional hour per day], 1.5 years (β = - 0.95, 95% CI: - 1.85 to - 0.06), and 6 years (β = - 0.88, 95% CI: - 1.55 to - 0.21) had persisting associations with poorer academic performance at age 9 years. Greater screen viewing time at ages 1 year (β = - 1.12, 95% CI: - 2.07 to - 0.17) and 6 years (β = - 1.01, 95% CI: - 1.71 to - 0.31) was associated with poorer working memory at age 10.5 years. Cumulative average exposure models showed that screen viewing time over childhood was consistently associated with poorer academic performance but not working memory.

In this longitudinal study, cumulative average screen viewing time was associated with lower academic performance but not working memory, with the strongest effect sizes seen for single screen viewing time occurring in early infancy.