Theories of negative effects of video games tend to focus on players' modeling of behaviors observed in the game. These effects may be exacerbated due to the interactive nature of these games. The most well known theory of such effects is the General Aggression Model (GAM), which proposes that playing violent video games may create cognitive scripts of aggression which will be activated in incidents in which individuals think others are acting with hostility. Playing violent video games, thus, becomes an opportunity to rehearse acts of aggression, which then become more common in real life. The general aggression model suggests the simulated violence of video games may influence a player's thoughts, feelings and physical arousal, affecting individuals' interpretation of others' behavior and increasing their own aggressive behavior. Some scholars have criticized the general aggression model, arguing that the model wrongly assumes that aggression is primarily learned and that the brain does not distinguish reality from fiction. Some recent studies have explicitly claimed to find evidence against the GAM.
Some biological theories of aggression have specifically excluded video game and other media effects because the evidence for such effects is considered weak and the impact too distant. For example, the catalyst model of aggression comes from a diathesis-stress perspective, implying that aggression is due to a combination of genetic risk and environmental strain. The catalyst model suggests that stress, coupled with antisocial personality are salient factors leading to aggression. It does allow that proximal influences such as family or peers may alter aggressiveness but not media and games.
Research has focused on two elements of the effects of video games on players: the player's health measures and educational achievements as a function of game play amounts; the players' behavior or perceptions as a function of the game's violence levels; the context of the game play in terms of group dynamics; the game's structure which affects players' visual attention or three dimensional constructional skills; and the mechanics of the game which affects hand-eye coordination. Two other research methods that have been used are experimental (in a laboratory), where the different environmental factors can be controlled, and non-experimental, where those who participate in studies simply log their video gaming hours.
A common hypothesis is that playing violent video games increases aggression in young people. Various studies claim to support this hypothesis. Other studies find no link. Debate among scholars on both sides remains contentious, and there is argument about whether there is or is not consensus regarding the effects of violent video games on aggression.