Greg Tito said:
First off, blasting more sound at someone is hardly an accurate measure of aggression and probably speaks more to the sound design of the games played.
There was a study a while back that tried to determine whether violent television would cause violence. In this experiment they let subjects administer shocks to people, and the intensity of the shock given was to be the measurement for violent behaviour after said subject had watched either a violent or non-violent television program.
This experiment is very similar with the addition of measurement of brain activity. The only reason they won't shock people this time is because it's considered unethical. The study of psychology took a while to realise you can't just shock people for the sake of science. I bet GlaDOS would disagree, but hey.
The experiment isn't flawed in and of itself. administering loud noises to other people is like exposing them to pain, only less so than shocks. Now if they would've gauged the volume of some song or other sound that the subject would set after playing the game, that would surprise me.
That being said it's been well known that violent imagery makes people violent. It's also been known this effect does not last long after a person has stopped playing.
It's also been known that if you see something all the time, like gore, violent behaviour or anything else violence-related you will get used to that imagery. It's what desensitisation means. What it doesn't mean, however, is that you will also get desensitised to those same images out of their original context. I can look at people getting maimed, blown apart and tortured in video games all day long without flinching, even laugh at some times. But when I watch one of those tv programs that shows a real life surgery going on sopmetimes I get very uncomfortable.
So no, it's not a bad study. It's what people infer from the study that could be bad.