Influence of games psychologically

I have been looking into studies that examine the effect that games have on gamers psychologically. I am doing this to see whether games have can influence or change an individual. I have found some interesting studies linking violent action games with an increased mental ability for concentration, multi-tasking and decision making.

http://healthland.time.com/2011/12/02/how-playing-violent-video-games-may-change-the-brain/