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Are screens melting kids’ brains? Parents certainly think so. We’re trying to ban screens in schools, which kids hate and so try all sorts of creative ways to circumvent the rules.
We don’t apply the same rules to ourselves, of course. This morning nearly every single adult in my train carriage spent the entire trip looking at their phone – as did I.
Are screens melting kids brains? Parents certainly think so.Credit: iStock
Certainly, there are plenty of big studies that report worrying results.
A large Japanese study published in JAMA this year found a dose-response relationship between screen time at age 1 and delays in some categories of development at age 4.
And this study linked screen time at 12 months to changes in a child’s brain structure, and then linked those structural changes to effects on executive function and attention at age 9.
Scary!
But screen-time research on kids turns out to be very noisy, and it can be hard to get a clear signal. Consider these two large studies, involving almost 30,000 children and teenagers, which found only very modest effects from screen exposure.
To answer the question of what screen time is doing to kids, we need systematic reviews that combine large datasets. An intriguing new one dropped from Australian researchers this week, pulling together data from 2451 studies involving more than 1.9 million children and teenagers.
Its key conclusion: screen time does affect development, but the impact is very small and inconsistent.
“I think it’s surprising how small these effect sizes are, overall,” says lead author Dr Taren Sanders, a research fellow at the Australian Catholic University’s Institute for Positive Psychology and Education. “For some kids, in some circumstances, [screens] certainly do matter. But on average, we saw very small effect sizes – which means you’d need a really large dose of exposure to have meaningful effects.”
Screen time’s effect on kids development is… complex.Credit: iStock
The review, published in Nature Human Behaviour on Monday, is quite a fun read compared with many of the dull and jargony papers that cross the Examine desk.
We start with a tour of history. Screen time isn’t the first technological Satan threatening kids’ minds. In the 16th century we were worried about the influence of those newfangled books that were starting to be printed. Then we got radio, and parents worried it would distract kids from reading books (by now considered good, rather than bad).
Now we have television and mobile phones, and again we hold serious fears about what these devices may be doing to our children.
And hey, that’s not unbridled hysteria – public health messages really do seem to suggest screen time is something to fear. Australia’s guidelines recommend no screen time for kids under 2 – zip, zero, zilch – and no more than an hour a day for kids under 5.
To me, that sounds like a little goes a long – and harmful – way. But that’s not what Sanders’ study concludes.
Looking at educational effects, it finds a very low negative correlation between screen use, video games and television viewing and learning, that explains about 1 per cent of the variance between kids. In other words, everything else unrelated to screen time explains 99 per cent of the variance.
But this is complex. Educational video games seem to improve learning, as do educational apps.
And – I think this is important – co-viewing, that is watching television with a parent, seems to have positive effects on literacy (more on this in a sec).
Researchers have known for some time that content matters when it comes to viewing television – and it’s all thanks to Sesame Street. Studies run after it launched in 1969 showed immediate and sizable increases in kids’ test scores. And a 2015 analysis showed this effect was generational, bumping up the school readiness of kids who watched Big Bird, Oscar and friends.
How much does that 1 per cent correlation between time spent on screens and variance between kids matter? The answer is complex.
For kids who watch only a little TV, say less than an hour a day, the effect is very small – “tiny”, says Sanders. But the relationship is linear – as you watch more TV, the effects increase.
“At very low levels, these effects are probably not that important. At extensive levels, these effects are probably very important,” Sanders says.
There’s a second key point here: nearly all data we have on TV viewing is observational. And as regular readers of Examine will know, observational data is very messy.
Credit: iStock
What else is happening in the life of a child who is watching a lot of TV? Is the TV being used as a babysitter? Could TV watching be a proxy measure of parental involvement – which we know has a major effect on children’s learning outcomes. Other studies show it is families from lower socioeconomic backgrounds, or children of mothers with postpartum depression, who are more likely to watch more TV.
And think about the parents who don’t let their kids watch any TV. I know some, and they are very intense about giving their child the best possible upbringing.
This would make sense when you consider the positive development outcomes seen when parents watch TV with their kids. Is that really the mechanism – or is it a proxy for parents being involved? “I don’t think it’s plausible that a parent sitting on a couch, on their phone, not paying attention to the TV has an effect on kids’ literacy skills,” says Sanders.
Not quite, Sanders says. His data does not refute existing guidelines as much as suggest that they should be nuanced.
The recommendation for zero screen time under age 2 still makes sense, he says. We don’t have a lot of good evidence in the area, and development experts hold real concerns about substituting play and learning for screens at such a critical development stage. “Those interactions are much, much more important than anything screen time can provide,” says Sanders.
But for older kids, future guidelines should focus less on time spent on screens and more on context and content, he argues. “It’s not just kids engaging in screen time, it’s what they watch. And we think that’s what the guidelines really need to head towards.”
Liam Mannix’s Examine newsletter explains and analyses science with a rigorous focus on the evidence. Sign up to get it each week.
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