I'm not sure it is so simple. As a point of counter anec-data I was always kind of concerned about this, and I even developed a slightly unhealthy habit with my phone when I sank into depression. In any case, we decided an iPad for our son might be helpful for education and we bought one for him/us when he was 1. He used it quite a lot and he learnt maths really early. As he has grown up - now 3, he only occasionally uses his iPad. To be honest, I find it quite strange that it hasn't turned out how we all would expect it to. I've been conscious to not put crappy advertising games on there, or anything with psychological hooks. But I honestly don't think it is the device that is the root of the problem.