My two boys, very close in age(4-5), play on my ipad, we've also learned quite a bit and been able to explore in ways that books nor the internet could show us (eyeballs, bugs, skeletons, all sorts of stuff kids ask). If I allow too much ipad time, one gets extremely agitated and distressed. while the other doesnt seem to be affected. So i guess what worries me is that I hope for the 1 in 2 boys who are going to devellop attention disorders or anxiety from it are monitored appropriately. the effects are very dangerous if not caught quickly.