Young children exposed to high levels of screen time are more likely to show delayed early childhood development in key areas such as communication, motor skills, problem-solving and personal social skills.
Our Canadian study of over 2,400 children aged five and under has, for the first time, shown a clear link between levels of screen time and children missing developmental milestones.
The study does not tell us everything we need to know, and we should avoid alarmism. However, it identifies an avoidable risk that large numbers of young children may face if their screen time is not reduced or not shared with a co-viewing caregiver.
Managing screen time is an opportunity for parents
Our findings also provide a fairly straightforward opportunity for parents to support their children’s development. For many parents, better managing young children’s screen time is easier than reducing factors such as poverty that can also delay early childhood development.
On a grander scale, our study offers policy makers a challenge to influence and support parents. By school entry, one in four children in North America shows deficits and delays in early childhood development outcomes such as language, communication, motor skills and/or socioemotional health. Adapting screen use may be a way to reduce these deficits.
Uniquely, our study measured children’s screen times at two, three, and five years of age. Early childhood development outcomes at each of these ages were also assessed by mothers. So we were able to show that screen time at age two predicted development at three and, likewise, that screen time at three predicted development at five.
“This is an opportunity for parents – better management of screen time can be easier than reducing factors such as poverty that can delay early childhood development.”
Mothers were asked to report, for example, whether their two-year-olds could combine two or three words, such as ‘mum, cat, gone’ and whether, at age five, they could use four or five word sentences. Measures for the different ages were also reported for other motor, problem-solving and social skills.
Screen time link to missed early childhood development milestones
We now know, from our study, that increased screen time predicts delays in children meeting their early childhood development targets later on. However, our study was not designed to prove causality. Showing causality requires a randomised controlled trial, which would be unethical in this case, since we would have to expose large numbers of children to high levels of screen time.
However, our study – calculating screen time first and then testing child development years later – shows important elements that underpin causality: directionality and the fact that screen time precedes the underachievement of child development targets.
That helps us clarify a question raised by previous snapshot studies which measured screen time and levels of child development only at a particular moment, rather than over time. Those studies were unable to demonstrate what comes first: delays in early childhood development or excessive screen viewing time.
Big advance on snapshot studies
The previous snapshot study findings were consistent with an explanation that young children who are already showing signs of delayed early childhood development may be given extra screen time in the mistaken belief that it can boost their achievement. Our study squarely links developmental problems to prior screen exposure.
Our study also indicates that screen time is an important predictor of early childhood development and that its impact is on par with many other determinants of child development, such as parenting, socioeconomic status, sleep and physical activity.
However, unravelling the independent role played by screen time is complicated because watching screens interconnects with these other factors. For example, screen time can reduce time available for sleeping.
What is the tipping point for screen time?
Many important questions remain unanswered. We do not yet know if there is a tipping point for screen watching by children at these ages: How much screen time does it take to adversely affect early childhood development?
Nevertheless, our study highlights that large numbers of children, at least in industrialised societies, may be at risk, given their levels of screen time. Most of the children in our study exceeded Canada’s paediatric guidelines, which recommend that children should spend no more than an hour per day viewing high-quality programming. In our study, children aged 24, 36 and 60 months were, on average, watching screens for approximately 2.4, 3.6 and 1.6 hours per day, respectively.
“The study shows that screen time precedes the underachievement of early childhood development targets.”
We also need much greater understanding of both the content and the context of screen time. Our study reported time spent on various devices, such as VCRs, DVD players and computers, as well on different formats such as movies, gaming and television programmes. It could be that some content is fine and other content is detrimental.
Possible reasons for our results
We already understand some of the mechanisms that could explain why screen time is linked to early childhood development problems for young children. For example, other studies have shown that children under 30 months old cannot apply what they learn on a two-dimensional screen to three dimensions in real life. We also know, from other studies, that sharing screen time experiences with caregivers, rather than watching a screen alone, can be important for young children, because shared conversations support understanding and language development.
Our study was not designed to distinguish between a child watching a screen alone and viewing with someone else. Co-viewing with a parent or caregiver who can prompt and label experiences can be a very different and more developmental experience, particularly for very young children. So it would be helpful if future screen-time studies could distinguish between co-viewing and solo viewing.
We also need to know which of the early childhood development milestones are particularly impacted by high levels of screen time. Our study was not designed to separate the impacts.
Our message to parents is to be mindful about screen time. Child development is at its most rapid between birth and age five. The digital interface is highly stimulating and rewarding for children, and it seems to interfere, clearly and measurably, with development, in ways that we don’t yet fully understand.