“Yesterday after I wrote to you, I had an attack of asthma,” Marcel Proust wrote to his mother in 1901. “[It] obliged me to walk all doubled up and light anti-asthma cigarettes at every tobacconist’s I passed.”

While that sounds a bit crazy by 2018 standards, Proust was far from alone: “Medicated cigarettes marketed for respiratory complaints continued to be endorsed, and smoked, by doctors until well after the Second World War,” writes medical historian Mark Jackson.

Of course, tobacco eventually joined the list of treacherous substances once thought to be healthy and subsequently discovered to be harmful, keeping excellent company alongside radium and mercury. It's enough to make people constantly wonder what else might make it onto the list of friends turned foe. Could coffee be next? Processed meat?

There has been a steady stream of worry that digital media could be next. According to mountains of thinkpieces and concerned researchers, our screens are rendering us the very opposite of zen—increasing the risk of ADHD in children, making them more violent, and leaving us all distracted, twitchy, and depressed.

Recently, PNAS took a look at what we actually know about these risks, publishing a series of papers focused on “Digital Media and Developing Minds.” Collectively, this work explores the current state of research on this broad question lingering in the back of many minds: what impact do screens have on our brains, especially the developing noggins of everyone from children to young adults?

Not a monolith

The lumping of everything digital into a monolith is a framing that makes Oxford Internet Institute psychologist Andrew Przybylski groan. “We don’t talk about food time,” he points out. “We don’t talk about paper time. But we do talk about screen time.”

The diverse uses of our screens make it tricky to ask any broad questions. Those screens are the gateway to a vast variety of experiences, including friendship, education, bullying, work, violence, entertainment, and information overload. But there are common threads in this field of research, largely in the shared difficulties researchers face—a swiftly changing technology landscape, a profusion of non-digital influences, small sample sizes, a skewed publication record, and (perhaps the trickiest aspect of them all) the difficulty of establishing a causal link in a sea of correlations.

The new series of papers includes a look at childhood screen use and ADHD, the effects of media multitasking on attention, and the link between violent video games and aggression. The separate papers are a good reminder that these are really separate issues; even if screen time ends up being problematic in one area, it doesn't mean it can't have a positive effect in another.

Violence in games

One of the papers that grabbed headlines tackled a popular subject of blame: “Study confirms link between violent video games and physical aggression” reported USA Today, and “More evidence video games may trigger aggression in kids” trumpeted health24.

As the headlines imply, this is not out of the blue. Studies have been reporting findings in this vein for years. More recently, there have been meta-analyses—papers that combine the results of large swaths of research to look for an overarching result—that have added strength to those findings. But debate is ongoing, with skeptical researchers like Patrick Markey and Chris Ferguson leveling some thorny critiques. There's often little consistency in how aggression is measured and whether other social factors are accounted for in the analyses. Researchers also argue that bias for which of the results see the light of day could play a role in the emerging picture.

For Jay Hull, one of the authors of the headline-grabbing paper, video games and violence wasn’t a primary research interest. His career has looked at self-regulation, self-knowledge, and self-control, exploring topics like smoking and reckless driving among teenagers. When he got involved in the work on video games and aggression, his goal was to answer the question to his own satisfaction. He says, “I thought, OK, if I’m going to take a serious look at the current state of the research, I want to address the criticisms.” He didn’t care how the results turned out, and he adds, “I’m willing to say there isn’t anything there if there’s nothing there.”

So Hull and his colleagues put together a new meta-analysis. They left out studies that measured aggressive attitudes and emotions and focused exclusively on those that reported some kind of real-world physical aggression, including self-reports of aggressive behavior or reports from parents or teachers. They were careful to account for as many other possible explanatory factors as they could. And they looked for statistical signals of publication bias—the possibility that studies that failed to find a link had been buried in a file drawer somewhere, leaving a skewed picture in the published research.

The meta-analysis showed an effect: the more violent the video game play, the more the aggression. The effect was statistically significant, meaning that pattern in the data was very unlikely to pop up just due to the kinds of random noise you get in any data. Whether it’s a practically significant finding is another question. “The relationship between video game play and aggression is less than one percent, using their own stats,” says Markey. “So 99 percent of the variability in aggression is going to be explained by something other than what’s measured.”

Hull and his colleagues concede this in their paper but argue that it’s maybe not the most appropriate way to think about the numbers. Relative risk might be better, they suggest—how much more likely is your kid to be aggressive with access to violent games? A previous study of Hull’s found that kids with high exposure to mature games got sent to the principal’s office for fighting twice as much as those with low exposure—but even then, the rate was approximately ten kids out of every thousand, compared to five out of every thousand.

Markey, who is highly critical of the idea that games lead to violence, thinks that the analysis is sound but has bones to pick with the way the research is presented in the paper and the media. “When people think of physical aggression and video games, we’re thinking of school shootings and aggravated assault,” he says. But the measures of aggressive behavior in this meta-analysis are predominantly self-reports, where children are invited to agree or disagree with statements like “when I get mad, I break things,” he explains.

The danger here, he argues, is creating a red herring in the face of what people are really scared of. “All this focus on video games! Meanwhile we’re not worried about things like gun control, economic issues, or media portrayals of [school shooters]. If we become distracted with things like video games, it takes our eyes off what might be a bigger issue.” That’s where the practical significance of the finding looms large: if video games explain only a tiny portion of aggressive behavior, other factors should probably be getting a lot more airtime.

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