A University of Auckland review of 58 studies has found that 81 percent show heavy screen use in children is linked to weaker attention, planning and impulse control

A new University of Auckland review of 58 international studies has found that 81 percent of them link higher or problematic screen use in children with weaker attention, planning and impulse control, and that the heaviest users may be showing physical changes in how their brains develop.

The work was led by Claire Reid, a PhD researcher at the University’s School of Psychology, and published in the journal Developmental Review. It pulls together evidence collected between 2013 and 2024 from studies based in Asia, Europe, North America, Oceania and South America, with all participants aged 18 or under.

Reid told RNZ the pattern across the literature was striking. She said the review showed “a really clear pattern” in which higher or problematic screen time predicted difficulties with attention, focus, planning and impulse control, and could line up with long-term physical changes in children’s brains.

Of the 58 studies in the review, eight used neuroimaging to look directly at the brain. Reid said those were the ones that worried her most, with the imaging research suggesting that heavier screen use was associated with reduced brain growth and weaker connectivity between different brain regions, the cabling that lets the parts of the brain talk to each other and coordinate complex tasks.

Executive function is the umbrella term for the mental tools that allow a child to focus on a task, hold information in mind, plan a sequence of steps, and resist the impulse to do something else. Those skills underpin most of what schoolwork demands, and they keep developing well into adolescence. The studies in the review used a range of well-established cognitive tests to measure them, alongside parent and teacher reports.

The review covered a broad sweep of screen activity, including time spent watching video, online behaviour patterns, gaming, and social media use. The vulnerable groups that emerged from the data were familiar from previous research. One Portuguese study of children aged one to three and a half years found that touchscreen exposure was associated with faster reaction times but also with greater distractibility, and Reid said children with attention deficit hyperactivity disorder appeared particularly susceptible to problematic patterns of use.

Reid was careful about how far the findings can be pushed. The review did not establish causality, she said, because other factors that travel alongside heavy screen use, including poor sleep, low levels of physical activity, and reduced social interaction, are themselves known to affect the developing brain. Disentangling those threads is one of the hardest problems in this area, and Reid said it was an open question whether screens were doing the damage directly or whether they were a marker for everything else that goes with sedentary indoor childhoods.

What the research did suggest, though, was a plausible mechanism. Reid said the most consistent theory to come out of the review was that screens were displacing “really important developmental activities” that young brains rely on to grow well, including back-and-forth conversation with parents, unstructured play, and face-to-face socialising with peers. In that account, the harm comes less from the device itself and more from what the device crowds out of the day.

The implication for parents and teachers is therefore not necessarily a panic about screens but a closer look at what is being lost. A child who spends three hours a day on a tablet is, by definition, not spending those three hours talking, climbing, drawing, arguing with a sibling, or working out how to share a ball at the park. Those are precisely the messy real-world tasks that ordinary executive function development depends on.

The Auckland review lands at a time of growing international interest in screen-time guidance. The World Health Organisation already recommends no screen time at all for children under one and no more than an hour a day for those aged two to four, while several European countries have introduced phone bans in primary and intermediate schools. New Zealand has stopped short of formal national rules, but the Ministry of Education has tightened guidance on phones in classrooms and a number of schools have moved to lock-bag policies during the day.

For health and education researchers, the next step is harder evidence about cause and effect, and ideally New Zealand-specific data on how local children are using their devices. Reid’s review concentrates on the global picture, but she has flagged a need for longer-term studies that follow the same children over time and tease apart the role of sleep, exercise and family time.

For now, the practical message from the work is modest and familiar. The clearer the link between heavy screen use and weaker self-control, the stronger the case for protecting time for the things that screens tend to push out, including conversation, sleep, outdoor play and unhurried attention from a trusted adult.

How does your household manage children’s screen time, and have you seen a difference when you have pulled it back? Share your experience in the comments below.