I'm running out of entertaining "violence" images for these research articles.
A recent study out of Université Pierre-Mendès-France, conducted with researchers from Ohio State University and the University of Hohenheim suggests that there may be a cumulative effect in aggression and the expectation of hostility among players of violent video games.
The researchers assigned 70 undergraduate students to play either violent video games (Condemned 2, Call of Duty 4, or The Club) or non-violent video games (S3K Superbike, Pure, or Dirt 2) for twenty minutes on three consecutive days. After each session, participants were asked to read the beginning of a story and then come up with twenty possible actions for the main character to take. Researchers then coded participants' responses, counting how many aggressive or violent actions were included. Subsequently, participants were told they would engage in a competitive task with an unseen other participant (there was no other participant); participants were told they could send the "other player" a noise blast through their headphones, and that they could choose how long and loud it would be.
The researchers found that those who played the violent video games gave more aggresive/violent actions for the story's main character, and gave the fake other participant a louder, longer blast of noise. Brad Bushman, one of the lead researchers, holds that:
People who have a steady diet of playing these violent games may come to see the world as a hostile and violent place...These results suggest there could be a cumulative effect.
And:
Playing video games could be compared to smoking cigarettes. A single cigarette won't cause lung cancer, but smoking over weeks or months or years greatly increases the risk. In the same way, repeated exposure to violent video games may have a cumulative effect on aggression.
Unfortunately, none of the reports linked above mentions the size of the effect, only that it is statistically significant. But a statistically-significant increase can be anywhere from a fraction of a percent, to a thousand-fold, or more. Data from the study's publication in the Journal of Experimental Social Science suggest the violent-video-game group was about twice as hostile and twice as aggressive on the study's measures as the non-violent-game group after three days. What happens after three days, however, is anybody's guess.
Interestingly, the results of this study contradict earlier research that suggests the degree of competitiveness a game, rather than the degree of violence, is responsible for the increase in aggression.

Video games have been taking lessons from psychology for quite some time; heavily-stimulating with quick rewards, they've been providing gamers' brains with bursts of dopamine since they first graced the primitive displays of yesteryear's mammoth computers. Ever since, the anxious parents of the world have been wondering what on Earth all of this overstimulation will do to the children - as though that were even remotely important compared to the steady stream of anxiety-inducing, self-esteem crushing stupidness from the adult world (you know, like resource wars, body shame, homophobia, classism, and so on). Meanwhile, saner other people spend more time wondering why oh why they spent so much time playing Angry Birds.
Well, game designer and psychologist Ariella Lehrer lays bare in interview with ABC what should already be apparent to students of psychology: Casual game designers are using the same operant conditioning techniques that casinos use to hook players.
Operant conditioning is one of the most fundamental mechanisms of learning; it describes how rewards and punishments can be used to shape animal behaviour. Give someone a treat for pressing a button, and they'll keep pressing the button; this is called "conditioning." Stop giving them the treat, and after a while they'll stop pushing the button; this is called "extinction." What Lehrer argues that casual game makers (herself included) are doing to hook gamers is using a different reward schedule, intermittent positive reinforcement. In this system, the reward for performing a behaviour is only sometimes reinforced, exactly like slot machines in a casino. Knowing that they might win, the player pushes the button more and more, and occasional wins entrench this behaviour.
One of the most worrisome aspects of intermittent positive reinforcement, especially in regards to gambling and compulsive behaviour, is that extinction is harder to induce than with any other form of reinforcement (except for extremely deeply-ingrained conditioning paradigms oriented around survival, such as taste aversion). This helps explain the "just one more try" effect many games, especially clever casual and puzzle games, instil in their players.
While it's not surprising that games are using this technique to hook players and keep them that way, what is illuminating is that at least one designer is admitting that they are purposely doing it to snare people within the first twenty minutes of play.
Scrutiny of the portrayal of gender and sexuality in video games has (thankfully) been growing in recent years. Headline-making controversy over tent-pole games like Tomb Raider, Metroid: Other M, and Dragon Age keeps popping up as both gamers and game makers (a bit of an arbitrary distinction, as most game makers are themselves gamers) awaken to issues of gender role stereotyping. It would be easy to posit that this would be a slow awakening as gaming is an industry run mainly by males from majority demographics - people who are rarely exposed to what it's like to live without their privileges - but this would ignore the complexity of the societal and financial forces (again, a false dichotomy as society and finance are inextricably intertwined) at work in the industry.
A new piece of research by Christopher Near of the University of Michigan, published recently in the journal Sex Roles, explores how some of those forces play out. In particular, the research examines the relationship between the portrayal of gender roles in box art and game sales themselves. Near posits that a focus on non-sexualized female characters (Princess Peach, for example) would be related to lower game sales, while box art focusing on men of any type would be related to higher sales; further, box art in which female characters are not the focus but are sexualized (Cortana, for example) would sell better. To quote the author:
In short, it is expected that "sex sells," but only when the sexualized women portrayed are also depicted as marginalized, consistent with a gender coding of the game that fits cultural stereotypes (Kimmel 2008). In this view, the success of Lara Croft was anomalous, as she was depicted as a central (albeit highly sexualized) female protagonist in the box art for Tomb Raider.
Follow along after the jump.