I can't substantiate this claim in any way, but I think the game's genre also matters. I think that the kind of game impacts the child's neural development in different ways. A game like Call of Duty, which is entirely twitch shooting and instant gratification, is building a reward system in the child's mind for these kinds of activities. I honestly think that a game like Call of Duty impairs a child's mental development because it grounds them in base ventures. On the other hand, fighting games, strategy games, RPGs, etc. all reward tactical thought and patience. I think they offer a different kind of reward system, and thus they are much better for children to play.
As a kid, I played a lot of RPGs. Did they have violence? Absolutely. But I also had to figure out things like materia combinations, weigh Esper stat changes, and decide on what combo techs I wanted. Tactics games are even more intense in this area. Hell, I taught my little sister to read through RPGs. I learned a lot about critical thinking through these games, though. If chess is good for kids, then, aside from problems inherent to the media (TV viewing), I don't see why RPGs, fighting games, and strategy games would be bad. And I think chess is great for kids.
On the other hand, a game like Call of Duty is more like Hungry Hungry Hippos (thanks to my wife for that analogy). Would you want to raise your kids on Hungry Hungry Hippos?
