Environmental Cues for Aggression

In 1967, Berkowitz & LePage published an article describing a set of experiments in which the mere presence of a handgun, placed benignly on a table in the corner of the laboratory, elicited increased aggression among research participants. This phenomenon has since become known simply as the weapons effect, and has been replicated numerous times. The theoretical basis for the weapons effect is that certain cues can become linked in memory with aggressive and violent behavior. The mere presence of these cues in the environment is often enough to bring aggressive thoughts and feelings to mind, which under the right circumstances can engender increased aggressive behavior in the perceiver. My colleagues and I have examined a number of such phenomena involving not only weapon cues but also other elicitors of aggression, including alcohol and violent media.

In a series of studies extending the original weapons effect paradigm, my colleagues and I have shown that the presence of weapon pictures or weapon names brings aggressive thoughts to mind (Anderson, Benjamin, & Bartholow, 1998). We have also shown that this process can depend upon individual differences in experience and associations with guns. For example, hunters, who tend to associate hunting guns with enjoyment, relaxation, and fun times with family and friends, do not show the weapons effect when presented with images of hunting guns, but do show the effect when presented with images of assault guns (Bartholow, Anderson, Carnagey, & Benjamin, 2005). These findings indicate that idiosyncratic differences in knowledge structures, based on different experiences, can determine the extent to which a given cue becomes associated with aggression (see Berkowitz, 1993).

In other research, my colleagues and I have investigated the effects of the mere presence of alcohol-related cues on hostile thoughts and aggressive actions (Bartholow & Heinz, 2006; Friedman, McCarthy, Bartholow, & Hicks, 2007; Pedersen, Bartholow, Vasquez, & Loersch, in preparation). We have found, for example, that passively viewing alcohol-related images causes research participants to interpret the ambiguous behaviors of a story character in a relatively hostile way, compared to participants who initially view other kinds of images. This effect is particularly pronounced among individuals who tend to associate drinking alcohol with increased aggression (i.e., aggression-related alcohol expectancies). We have also seen similar interactive effects when sub-optimally priming participants with alcohol-related words (vs. control words) and then giving them an opportunity to aggress against an experimenter.

A final paradigm in which my colleagues and I have investigated environmental cues to aggression is in the area of violent media (Bartholow & Anderson, 2002; Bartholow, Sestir, & Davis, 2005; Carnagey, Anderson, & Bartholow, 2007). It is widely accepted among many researchers that exposure to violent media (e.g., video games, movies, TV) causes an increase in aggressive behavior, at least temporarily. A former student and I (Sestir & Bartholow, in press) conducted a set of experiments designed to investigate (a) the temporal stability of the violent video game effect on aggression-related outcomes, and (b) whether nonviolent video games also produce changes in aggressive and prosocial thoughts and behavior. We found that participants who played a violent game were considerably more aggressive than participants who played a nonviolent game if aggression was measured within a few minutes after game play; after a 15-minuite delay, however, those who played a violent game showed a significant decrease in aggression, and those who played a nonviolent game showed a significant increase in aggression. These data indicate that nonviolent games – event those lacking explicitly prosocial themes or content – might have aggression-reducing effects in the short-term that oppose the aggression-enhancing effects of violent games.

We have also tested whether longer-term exposure to violent video games is associated with changes in brain activity related to desensitization to violence, which could then lead to increased aggression. In one study (Bartholow, Bushman, & Sestir, 2006) we found that subjects who reported playing a lot of violent video games showed a decrease in the amplitude of the P300 component of the ERP when viewing violent pictures, but not when viewing equally negative, nonviolent pictures, relative to subjects who reported relatively little exposure to violent video games. Moreover, this decrease in brain activity was associated with a significant increase in aggressive behavior during a later laboratory task. Recently, we completed a follow-up to this study in which we randomly assigned participants to play a violent or nonviolent video game prior to measuring their neural responses to violent and other negative pictures (Bartholow, Engelhardt, Bushman, & Kerr, in preparation). Data from this study indicate that the effect we reported in our previous work (Bartholow et al., 2006) is particularly pronounced following violent game play in the lab.