Earlier this week ARS Technica wrote an article about a new study which suggests violent video games may increase aggression without triggering any increase in anger:
The apparently contradictory results can be rationalized, and doing so may tell us something about why the whole topic is so confused.
To briefly recap the earlier study, researchers surveyed students about their general personalities and identified stable and unstable groups. They found that unstable personalities were affected by violent game content, such that those who were calm registered as being angrier after gaming and vice versa. Anger served as a proxy for aggressive behavior in this study, and only the momentary anger levels of the subjects was measured.
Contrast that with the newer study: here, anger was measured as a long-term personality trait, and actual measures of aggression were used to test for correlations among violent games, anger, and aggression. These subtle differences in experimental design mean that the two studies addressed questions that were almost unrelated, but identifying them requires reading the actual experimental design in the papers.
In the new paper, subjects played violent or nonviolent games, given three incomplete stories, and asked to provide 20 responses for how they would act if they were involved. The response of those playing violent games was more aggressive, but barely so: roughly nine out of the 60 responses were scored as aggressive, compared to about seven for those playing nonviolent games. These sorts of results are typical of the response caused by exposure to any violent media; the authors even note that a study that put people in a hot room registered a similar rise in aggression.