https://www.technologyreview.com/f/614672/screen-time-might-be-physically-ch... The study: Forty-seven 3- to 5-year-olds took a test to measure their cognitive abilities, and their parents were asked to answer a detailed survey about screen time habits. Questions included: How frequently do they use that screen? What type of content are they viewing? And is there an adult sitting with the child talking about what they’re watching? The answers were scored against a set of screen time guidelines put out by the American Academy of Pediatrics. The kids also had their brains scanned in an MRI machine. Brain changes: The scans revealed that kids who spent more time in front of screens had what the authors call lower “white matter integrity.” White matter can be roughly thought of as the brain’s internal communications network—its long nerve fibers are sheathed in fatty insulation that allows electrical signals to move from one area of the brain to another without interruption. The integrity of that structure—how well organized the nerve fibers are, and how well developed the myelin sheath is—is associated with cognitive function, and it develops as kids learn language. Lead author John Hutton of Cincinnati Children’s Hospital told MIT Technology Review there’s a clear link between higher screen use and lower white matter integrity in the children his team studied. That structural change appears to be reflected in the results of the cognitive test the kids took as well, which showed high screen time associated with lower levels of language and literacy skills. “The effect size is substantial, as these findings also rigorously controlled for multiple comparisons across the brain,” Hutton says. [...] Unfortunately, that’s not so easy. “It’s hard to say what the ‘safe’ age or amount of screen time is,” Hutton says. “My motto is ‘Screen-free until three’—this at least gets kids to preschool with a solid anchor in the real world, where their basic sense of connection with caregivers and early language skills have solidified.” Giacomo