Stop scaremongering about kids spending time on their phones

Correlation does not equal causation when it comes to screen time. 

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How much should we worry about our children using screens? It’s hard, as a parent, not to worry. Not least because we’re constantly surrounded by doom-laden warnings about how smartphones have “destroyed a generation”.

The problem is that, while the headlines are really, really stark, the evidence is really, really weak. Those headlines, which one psychologist I spoke to described as “scaremongering”, are based on studies that show small, ambiguous effects; they suggest that social media is the disease, when the research cannot show that it’s anything but a symptom; and almost all the studies are weak and badly designed, so even what little they do show we can’t take very seriously.

With all that in mind, it’s an enormous relief that the Royal College of Paediatrics and Child Health (RCPCH) has issued new screen time guidelines that are entirely sensible and acknowledge the weakness of the evidence. It says there is “essentially no evidence” to support the idea that screen time is directly toxic to health, despite wild claims in the media. It says there is some evidence that it can displace other activities such as exercise. But its main recommendations are simply to ask yourselves, as a family, whether your screen time is controlled, or whether it gets in the way of things you want to do – family time, eating together – and to try to control your use if it does. It also recommends that both adults and children avoid screens in the hour before bed, because a good bedtime routine helps sleep and sleep is important for your well-being.

This is the sensible approach. “I think [the recommendations] are the best we’ve seen from a professional organisation,” Andrew Przybylski, a psychologist at Oxford University’s Internet Institute, told me. “It’s being responsible in outlining the unknowns.”

The problems with the evidence that he refers to are, first, that almost all the studies simply show a correlation. For instance, a new study – coincidentally published today, although for some reason the paper itself is not yet online – found that girls who use social media a lot are more likely to be depressed. But it’s impossible to tell from the research whether girls who use social media become depressed, or whether girls who are depressed are more likely to use social media. “From this study you can’t say whether it’s a symptom or a cause,” says Suzi Gage, a psychologist at Liverpool University. She thinks it’s plausible that harassment and loss of sleep caused by social media could exacerbate pre-existing symptoms of depression, but it’s impossible, from this study or most others, to tell that. She adds that the most interesting thing, to her, is that it’s girls and not boys who suffer, and she wonders whether it’s a product of societal pressures on women that predate social media; a generation ago they might have been getting those pressures from glossy magazines.

That study, like almost all others, also relies on self-reported data: you ask someone how much they use their phone, and you ask them a series of questions to assess how depressed or anxious they are. But a recent study shows that self-reported data is only very tangentially related to how much people really use their phone. “We know that self-report doesn’t correlate very well with actual screen use,” says Brittany Davidson, a behavioural scientist at the University of Bath and one of the authors of that study.

What’s more, most of these studies are not “preregistered”. That means that the authors haven’t said in advance what they’re going to be looking for. That might not sound very important, but it means that it’s easy to find interesting-looking results which aren’t really there, as this XCKD comic shows.

If you’re allowed to cut your data apart in many different ways – slicing it by gender, or by age, or educational status – then you’ll probably find something just by fluke.

All of these things mean that it’s very hard to make out anything from the morass of weak studies and bad evidence. But even these poor studies themselves only show a weak effect, on the whole. Another much-hyped study in 2017 found links between depressive symptoms and social media, but as Przybylski’s colleague Amy Orben pointed out, social media explained much less than 1 per cent of the variance in symptoms in girls, and none at all in boys. That sort of tiny impact could easily be a statistical fluke, and even if it isn’t, it’s hardly the thing we need to be concentrating on.

Przybylski did a large, preregistered study a couple of years ago, which found that moderate screen use was correlated with a small uptick in wellbeing, while extreme use – several hours a day – was correlated with a small downturn. But it was much less than the impact of, say, skipping breakfast. If there is a real effect, it’s not exactly a plague.

Still, the screen time scaremongering continues. Partly it’s the fault of scientists and journals, for doing and encouraging shoddy, shocking science; and partly it’s the media’s fault for overhyping weak and uncertain results. “It’s a lot easier,” says David Ellis, a psychologist at Lancaster who specialises in the psychological impacts of technology, “to get the press to cover something about how tech is having a bad effect, than something which says it’s having very little effect.” The RCPCH’s guidelines are a refreshing change.