Excerpt from an excellent post. Definitely worth a read:
“Marathon 2 is typical of the violent games used in research.
There is a possible problem with this design. The researchers concluded that the violent nature of Marathon 2 was to blame for the increase in aggressive thoughts and mood, but it might have been that the complex nature of the controls were too much for new players to feel like they could do what they wanted in the game. This could then lead to frustration and a slightly hostile mood. In research parlance, this difference in the control complexity between the games is known as a “confound” because it offers an alternative explanation for the results.
This is exactly the thought that Andrew Przybylski (pronounced “Shuh-Bill-Skee”) and his colleagues (pronounced “colleagues”) had, and it lead them to an interesting study that was just published in the Journal of Personality and Social Psychology.5 In that study, they wondered how much frustration over one’s inability to master game controls contributed to aggression, as opposed to the violent content of a game.”