Does screen time at age two predict toddlers' executive function?
Toddlers who watched more screens at two years old did somewhat worse on self-control and working-memory tasks a year later, even after accounting for their earlier abilities.
Source
Screen Time and Executive Function in Toddlerhood: A Longitudinal Study
Study at a glance
- Design
- Cohort — Two-wave prospective cohort of first-born children: parent-reported daily screen time and lab-style EF task batteries at 24 and 36 months; regression controlling for prior EF, vocabulary, age and sex.
- N
- N=179 · 179 families with complete 24-month data were analysed (missing 36-month data handled by full-information maximum likelihood); 149 children had screen-time data at 36 months.
- Population
- First-born toddlers of cohabiting, English-speaking first-time parents recruited in the East of England.
- Outcome
- Composite executive function score at 36 months (working-memory search, card sorting, Baby Stroop and self-ordered pointing tasks).
Structured fields used in claim comparison tables when every cited study has a complete layer.
What they did
Both parents reported how long their child spent daily on TV, computers and touchscreens at 24 and 36 months. Children did hands-on executive function tasks at both ages, such as finding hidden toys, switching sorting rules and pointing to the 'wrong' spoon on command. Regressions predicted 36-month executive function from earlier and concurrent screen time, controlling for 24-month executive function, vocabulary, age and sex, and a second model tested whether poor executive function predicted later screen time.
What they found
Screen time rose from about 87 to 116 minutes a day between the two ages. More screen time at 24 months predicted lower executive function at 36 months (standardised beta about -0.20), but screen time at 36 months was not related to executive function at the same age. In the reverse test, only earlier screen time predicted later screen time; earlier executive function did not.
The limits
What it doesn't show
It is correlational, so an unmeasured factor such as parenting style or genetics could drive both screen use and executive function. Screen time came from parents' rough category estimates, not diaries or device logging, and the study did not know what children were watching or doing (adult vs child content, interactive vs passive, background TV). The executive function composites had only modest reliability, and the task batteries differed between ages, so the tasks do not show which specific component is affected.
Key terms
- Executive function
- A set of control skills including inhibitory control, working memory and cognitive flexibility that support goal-directed behaviour.
- Longitudinal design
- Measuring the same children at more than one age so earlier variables can be used to predict later outcomes.
- Baby Stroop task
- A toddler inhibition task where the child must point to the big spoon when told 'Baby' and the small spoon when told 'Mummy', overriding the natural association.
- Reverse causation
- The possibility that the outcome drives the predictor, here that children with weaker executive function are given more screen time.
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Quiz yourself
Which variable predicted lower executive function at 36 months?
Common questions
Does this show screens damage toddlers' brains?
No. It shows that earlier screen time predicted slightly lower later executive function after controls, but without an experiment other family factors could explain the link.
Why control for executive function at 24 months?
So the analysis asks whether screen time predicts change in executive function, rather than just reflecting that some children already had weaker skills.
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