The topic of kids and screen time—that is, how much time children with still-developing brains should be allowed to use mobile devices such as smartphones and tablets—has been subject to debate for many years. And while there’s plenty of anecdotal and scientific evidence to suggest that parents limit their kids’ screen time, the National Institute of Health (NIH) has undertaken a landmark screen time study.
The $300 million study follows 11,000 children at 21 testing sites across the country to assess how screen time, which includes mobile phone apps and video games, impacts their brain development and mental health, according to a new 60 Minutes report.
To conduct the study, teenagers lie in an MRI machine that scans their brains. While they lie in the imaging machine, a screen shows them images from their Instagram accounts. (Because of the magnets in the machine—MRI stands for magnetic resonance imaging—teens can’t have their actual smartphones inside the MRI chamber.) As the filtered images flick by, the MRI machine scans for certain brain responses, such as a spike in the brain chemical dopamine, which is associated with cravings.
In the first wave of 4,500 participants, researchers noted significant changes in children’s brain development if they have more than seven hours of screen time a day. It’s also already noticeable in the data that kids spending more than two hours a day on any type of screen received lower scores on language and thinking tests. And of course, other outcomes may not be seen for several years, as the scientists will have plenty of data points to study long after their official data collection concludes. Those longer-term outcomes may also impact screen time recommendations and guidelines for parents.
The NIH plans to release the report and its data in 2019 to other scientists working on similar screen time studies around the world.
