MPs looking for proof that smartphones and social media are rotting children's brains got a less satisfying answer from neuroscientists on Wednesday: nobody can really prove it. Appearing before the Science, Innovation and Technology Committee this week, three researchers spent much of the session explaining that concern and evidence are not quite the same thing. Asked what evidence exists on the impact of digital devices on infants and young children, Professor Denis Mareschal, director of the Centre for Brain and Cognitive Development at Birkbeck, replied: "There is very little, if any, causal research in the early years. Almost everything is correlational." MPs kept coming back to the question – and the experts kept coming back to the same answer. When questioned about social media's impact on adolescents, Professor Sarah-Jayne Blakemore of the University of Cambridge was equally cautious. "What evidence do we have of the impact of digital devices or social media on the adolescent brain?" she asked. "Almost nothing. There are a few small studies, but they haven't been replicated, and they're purely correlational." However, that didn't stop the witnesses from expressing concern. Blakemore noted that adolescence is a period when reward systems in the brain are highly active while regions involved in self-control are still developing. "Even as adults, it's really hard to put our phones down if we're seeing constantly interesting things, but as a child or an adolescent whose prefrontal cortex is developing, it's even harder," she said. For Dr Dusana Dorjee, a senior lecturer in psychology in education at the University of York, the bigger concern was displacement. Children learn self-regulation through conversation, play, sport, and social interaction, she said, which can be crowded out by excessive screen use. "What would children do if they were not on their devices?" she asked. "They would interact with others, they would play, they would have multi-sensory input that digital devices can't provide." The researchers were also reluctant to throw every screen into the same bucket. Mareschal pointed to evidence that video calls can help families stay connected, while Dorjee drew a distinction between educational apps and endlessly scrolling whatever an algorithm decides comes next. MPs also wanted to know whether neuroscience could settle one of the liveliest arguments in the debate: how old a child should be before they're allowed onto social media. "What neuroscience can't do is pinpoint a precise age," Blakemore said. "The individual differences in brain development are vast." AI companions also got their turn in the hot seat, and the answers were even fuzzier than they were for social media. "We don't really have any evidence, and that's one area where I think we really urgently need new evidence," Blakemore said. "We need to think about, and this is the research question, how children and young people are interpreting AI chatbots, and whether they're interpreting them just like they would be interpreting a friend's behavior and suggestions and mental states." If there was a takeaway from the hearing, it was that concern about digital childhood is running well ahead of the evidence needed to settle the argument. ®
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