Canadian preschooler’s trajectories of screen use and their association with executive functioning at age 5.

Child executive functions are mental processes that play a central role in their ability to plan and organize their thinking and behavior. Preschooler executive function skills are key determinants of school readiness and later academic outcomes. Across the early childhood years, these skills evolve rapidly. Although maturation plays a role, the quality of children’s early learning experiences also contributes to the development of executive functions. Too much screen time in early childhood has been cross-sectionally linked to lower executive functioning skills. Other research using brain imaging has found that child screen is linked to brain development, particularly in areas responsible for executive functioning. Limited research has examined longitudinal associations between patterns of young children’s screen use and their executive function skills. The objective of the present study is to estimate how child screen use trajectories between the ages of 3 and 5 contribute to the development of executive function skills at age 5. Data are from 315 preschoolers from Nova Scotia, Canada studied at three time points longitudinally during the Covid-19 pandemic. Study measures were collected remotely in the Spring/summer of 2020 and 2021. In the summer of 2022, home visits were conducted to directly assess child executive function skills. Screen time was measured using parent reported child hours/day of screen time (TV/DVDs, computers, video games consoles, tablets, and smartphones) at the ages of 3,4, and 5. Child executive function was measured at age 5 using the National Institute of Health Toolbox, which provides validated, and age-normed assessments of the inhibitory control and cognitive flexibility domains. Covariates measured at age 3 include child sex and effortful control as well as parent education and stress. Using latent growth modelling we identified a low (mean=.9 hrs/day, 23%), medium (mean=3.0 hrs/day, 56%), and high (mean=6.38 hrs/day, 21%) screen time trajectory. This three-group model had a significant LMR P-value and had a lower BIC value than a 2 or 4 class solution. Multiple regressions adjusted for covariates revealed that children in the low (ß =.28) and medium (ß =.20) screen time trajectories scored significantly higher on inhibitory control. Children in the low screen use trajectory group also scored higher than children in the high trajectory group on cognitive flexibility (ß =.28). Our results suggest that helping children follow the pediatric recommendation of spending a maximum of 1 hour per day using screens, may help them develop stronger executive function skills.