I would suspect that children who are given electronics at an early age–in my view, honestly, before age 12, which of course makes me a quasi-Luddite, but in any event before age 6 or so–tend to run around on playgrounds less, and to want to spend less time on them. They want to get back to their electronics.
This postulate could likely be tested. The meaning of all this, of course, could and should be debated endlessly, but in my view less spontaneous physical play makes kids stupider and duller. That iPad is not creating a little genius: it is creating a little Nazi.