Screen time effects in kids are hard to measure. This is why.

When scientists study the effects of screen time on children, there’s really only one thing parents want to know: How much is too much? 

While the Academic Pediatric Association guidelines suggest daily limits for high-quality screen-based programming, those recommendations are based on studies with significant limitations. In general, studies on the subject quickly become outdated or can’t prove a causal connection between a certain amount of screen time and any number of outcomes, including mental health and brain development.

Studying the effects of screen time on children is much harder than you might imagine because scientists often can’t get the best data to understand the dynamics at play. That’s why new research often feels promising to parents who are looking for reassurance. If a study hints at negative effects, parents can justify giving their kids less time in front of a television or device. 

Take, for example, a screen time study published this week in JAMA Pediatrics, which found an association between excessive screen time and later developmental milestones in toddler and pre-school age children. 

You’d be forgiven for thinking the study explicitly focused on smartphones and tablets; plenty of the media coverage paired stories with images of children holding mobile devices. Yet, the researchers didn’t ask parents about iPhones, iPads, Kindles, and Androids because they’d either just debuted or didn’t exist when the study launched in 2008. (The study authors believe parents logged such use in an “other screen-based devices” category.)

This doesn’t disprove the study’s findings, but it does reveal how digital media technology often evolves faster than researchers expect. That means survey questions about devices and apps, for example, can quickly become outdated. Researchers, like in the JAMA Pediatrics study, also typically rely on reports about screen time use from children and their parents, the latter of which can be unreliable since adults aren’t great at remembering how much time they’ve spent on their own devices. 

Even if scientists can observe and accurately record screen time use, they often can’t classify a child’s engagement. Spending time on YouTube to learn about space is a much different experience than watching and commenting on Logan Paul videos. 

The good news is that dozens of scientists who want to better understand how screen time influences child development know these limitations well, and are trying to revolutionize the field by creating new research tools. 

The future of screen time research

One of those scientists is Dillon Browne, co-author of the JAMA Pediatrics study and assistant professor of psychology at the University of Waterloo. 

“You need a really forward-thinking group of researchers to anticipate those innovations [in technology use] before they even come,” he says.

Browne envisions future research on screen time that’s designed to adapt to the rapid changes in technology use. That would mean finding efficient ways to update a study as digital media evolves. 

But for important ethical reasons, researchers can’t make sudden changes to experiments involving human subjects without additional scrutiny. That also means adding a single new question or device category to a study can take weeks or months, and timing is always a concern for scientists who need to move on to a new phase of their research. Browne likens the process of amending a study to rolling out a change in human resources software in a large corporation. And once researchers significantly change their questions, it’s difficult or impossible to compare certain types of data over time without skewing the results. 

Studies could be nimbler, he argues, if they could use “passive data collection” to quantify kids’ screen time. Instead of relying on self-reports, scientists could have children and parents in their study agree to install a third-party app on an Android or iPhone device that would send all the information about use that Google and Apple already collect to the researchers. Passive data collection can be highly controversial; Apple recently eliminated Facebook’s ability to collect such information this way after it learned the social media company had paid people for the access. 

But for academic researchers, real-time data that includes detailed information about how a user engages with a device and its content would reveal emerging trends and habits sooner than later. If parents gave their consent for this type of data collection at the outset, it might also make it easier to get approval from an institutional review board to make changes to the study. 

“Living in an ongoing experiment”

Florence Breslin, manager of clinical assessment and testing at the Laureate Institute for Brain Research and co-author of stud on screen time and brain development published last October, agrees that passive data collection is a key to answering complex questions about how digital media is used and how it affects children’s development. 

Breslin’s study used data from the Adolescent Brain Cognitive Development Study, a massive longitudinal research effort to understand youth brain development and child health that should yield new insights about how screens can affect kids. (Breslin is a co-investigator on the ABCD study.) The paper published last year found an association between “screen media activity” and structural brain changes that could be positive or negative, but it’ll take additional research to know more about the effects. 

The study included questions about which categories of media children used and provided relevant examples like YouTube, Skype, and Instagram. Partway through the process, Breslin and her fellow researchers noticed something unexpected: Some brand names they’d discussed or included in the survey disappeared. They’d talked with each other about how kids used the anonymous messaging app Yik Yak, but then it shut down in 2017. At one point, research participants tried to report that they used the short-form mobile video app TikTok, an app referenced in the survey by its former name Musical.ly. In the study’s second year, they changed the questionnaire to include new app examples. They also changed a question about watching TV or films to specify whether kids “stream” TV shows or films. 

“It’s important to remember that we are living in an ongoing experiment.”

“It’s important to remember that we are living in an ongoing experiment,” says Breslin, referring to the rise of digital media. “This is all new and we can’t possibly keep up with the pace the technology is going at.”

Collecting information about study participants’ screen time directly from the devices isn’t a perfect solution. It requires permission from parents wary of how their personal data is already being monitored and sold. It’s also not guaranteed to measure use on things like school laptops, gaming consoles, and streaming TV services, so self-reporting would still be essential. Google currently permits developers to tap its application programming interface (API) to collect this data, but Apple does not. Breslin and other researchers are hoping to persuade Apple to change its policy.

Even with these caveats, both Browne and Breslin believe passive data collection is a critical component for studying screen time use in kids. 

“If we can get the passive data, we can look and see over time, are children using more of this, less of that?” says Breslin. “Is their behavior changing, and is it changing [as they move] from video gaming to social networking to news? Is there actually a causal relationship?”

Parents shouldn’t wait on researchers

Both Browne and Breslin belong to a group of interdisciplinary researchers who gather to talk about studying screen time. A nonprofit charity called Children and Screens: Institute of Digital Media and Child Development regularly convenes Browne, Breslin, and hundreds of scientists and clinical researchers to study the wide-ranging effects of digital media on toddlers, children and adolescents.

Within the next year, the group plans to develop and release a toolkit designed to help researchers use the best possible methods to assess children’s screen time, screen use, and media habits, and how they influence development. It will also provide pediatricians with ways to measure and assess their patients for digital media use. 

“Objective scientific research is the goal,” says Pamela Hurst-Della Pietra, president, founder, and a major funder of Children and Screens. “I’m open to all the wonderful aspects of technology, both now and in the future, but I’m very open to trying to make sure that we do no harm.”  

“[D]on’t wait on us to tell you what the right amount of time is.” 

Parents shouldn’t expect a decisive answer about the effects of screen time in the near future, says Breslin. Studies underway now may take years to complete. While the results will help create more advanced guidelines for screen time, parents need to remember that every child is different. A kid with few friends at school may benefit greatly from making social connections on a mobile device, making extra screen time worth the risk. Another child might not see the same benefit while also losing sleep and physical activity as a result of excessive screen time. 

Breslin recommends that parents follow the current screen time guidelines from the American Academy of Pediatrics while also paying close attention to how their children respond to different aspects of digital media technology, particularly if it’s influencing their sleep, nutrition, and exercise. 

“You have to find what the right [limit] in your family is,” says Breslin, “and don’t wait on us to tell you what the right amount of time is.”