Three leading UK researchers from Birkbeck, Cambridge, and York told the House of Commons Science, Innovation and Technology Committee the evidence is largely correlational, not causal, but they still raised real concerns about adolescent brain development and the activities…
The popular belief that smartphones and social media are structurally rewiring children's brains rests on "very little, if any" causal evidence, three UK neuroscientists told Parliament this month. Most of the studies cited in the cultural panic are correlational, and many have not been independently replicated.
That was the near-uniform answer that Professor Denis Mareschal, director of the Centre for Brain and Cognitive Development at Birkbeck, University of London; Professor Sarah-Jayne Blakemore of the University of Cambridge; and Dr Dusana Dorjee of the University of York gave when MPs on the House of Commons Science, Innovation and Technology Committee pressed them, repeatedly, for proof that the devices in every teenager's pocket are physically remaking young minds. The committee was testing the science behind a political claim that has powered school phone bans, parental anxiety, and a generation of advice books.
The Register's parliamentary correspondent Carly Page reported on 14 June 2026 that Mareschal was blunt when asked what causal research existed in the early years. "There is very little, if any, causal research in the early years. Almost everything is correlational," he said. Blakemore was equally cautious when MPs questioned her about the impact of social media on adolescents, telling the committee the same thing in different words.
The distinction matters because the political debate has often collapsed the difference between "we have not found a link" and "we have looked and found nothing." The scientists' position, narrowly stated, is closer to the first: the field has not produced the kind of controlled, longitudinal work that would let a parent or a policymaker say with confidence that the phone in a child's hand is doing something specific to the brain. Several oft-cited studies, the witnesses implied, would not survive serious replication scrutiny.
The witnesses were not endorsing the "phones are fine" framing either. Blakemore used her appearance to underline that adolescence is, biologically, a period of heightened sensitivity to social reward and still-developing self-control circuitry. The prefrontal cortex, the region that governs impulse and planning, is not finished until the mid-twenties. Anything that systematically turns up the volume on reward, comparison, or interruption during that window is worth studying carefully.
Dorjee took a different cut. He told MPs his concern is not so much what screens do to a child's brain as what they crowd out: unstructured conversation, free play, sport, and the multi-sensory, physical experience that toddlers and older children used to take for granted. A child staring at a tablet is, by definition, a child not doing one of those things.
Mareschal added a useful qualifier the headline debate often misses. Not every screen is the same. A video call with a grandparent and an algorithmic short-video feed are not remotely equivalent experiences, and treating them as one undifferentiated "screen time" category has muddied the research.
What the committee is being asked, in effect, is whether the existing body of work can justify coercive restrictions on children. By the standard the scientists described, the answer for now is no. The right response to a weak causal case is not to relax concern, but to demand better studies before turning restrictions into policy.
The committee's questions, and the witnesses' answers, will feed into a parliamentary report on screen time and child development expected later this year. Whether the politicians accept the scientists' epistemic standard, or reach for the correlational findings anyway, is the next thing to watch.