How does using mobiles and other wireless gadgets affect how children's brains work? That's the question a major new study is trying to find out.
Funded by the government and big mobile companies, it will look at 2,500 11- and 12-year-olds from September.
It'll look at how kids think, remember and how well they pay attention - and then repeat the tests in 2017.
Researchers say "very little" is known about the impact wireless tech has on how children's brains develop.
Dr Mireille Toledano from Imperial College London explains more about what the study wants to explore.