Video Game Violence and Desensitization

What are the cognitive effects of violence in video games? A new study by Carnagey, Anderson & Bushman shows that as little as 20 minutes of playing a violent video game reduces the physiological stress responses usually evoked by violence. In other words, violent video games appear to have a desensitizing effect. However, there are a few caveats to this story.

First, the methodology: the authors measured baseline heart rate (HR) and galvanic skin response (GSR) in 257 college students over the course of 5 minutes, and then had each play either a violent (Carmageddon, Duke Nukem, Mortal Kombat, or Future Cop) or non-violent (Glider Pro, 3D Pinball, 3D Munch Man, Tetra Madness) video game for another 20 minutes. Then they took another 5 minute HR and GSR measurement, and then showed each subject a 10 minute film of actual violence (including beatings, stabbings, and shootings) while continuing to measure HR and GSR. At the conclusion of the experiment every subject rated the video game they played on a variety of traits (e.g., frustrating, boring, fun, etc).

The data relevant to violence-densensitization showed relatively small, yet statistically significant, differences between violent and non-violent video game players (hereafter: VGPs). First, there were no significant differences between the violent VGPs and nonviolent VGPs in terms of heart rate or GSR, neither directly after playing the video game, nor as a function of change from baseline to immediately post-game. However, sometime after playing the video game and while watching the filmed violence, the following two things happened:
  • Violent VGPs showed no change in HR - and a decrease in GSR;
  • Non-violent VGPs showed a large increase in HR - and no change in GSR.

These results are important, and while I believe that violent video games probably do have a densensitizing effect, there are a couple of alternative explanations for these data.


If you spend 20 minutes committing (simulated) violence, another 10 minutes of merely watching violent events may be relatively unexciting (even if the violence is "real"). Therefore, maybe the violent VGPs were already at a relatively maximum state of arousal after playing the video games, and thus were more likely to show no change (or even a decrease) in arousal while watching filmed violence. Likewise, perhaps the non-violent VGPs were relatively uninterested in their games, and thus more likely to show a change in arousal when viewing something unusual, like actual violence.

In fact, there are some reasons to believe this alternative explanation might be partly true. Violent games were rated as being WAY more action-packed (F(1,252)=53.48, p<.0001) and more frustrating. Although the authors say that violent & nonviolent video games did not significantly differ in several other traits (including "arousing," "exciting," and "stimulating"), they use a surprisingly strict requirement for statistical significance here (they mysteriously set alpha at .08). There are also trends in the data suggesting that non-violent video game players had a higher baseline GSR.


Humans can get used to just about anything. From this perspective, these results are not surprising: if I show someone violence, and then show them more violence, they don't react as much as if I had first shown them a game of pinball. It would be far more compelling if violent video games were more "real-violence-desensitizing" than tennis video games are "real-tennis-desensitizing."

A simple control for this explanation would have been a delayed testing group (in which violent VGPs waited another 1, 6 or 12 hours before watching more violence), or even a distractor task in between the video game and the violent film. But because we don't have either type of control group, the effects here could simply be due to boredom rather than densensitization per se.


As it turns out, the non-violent group showed no significant GSR change between playing the video game and watching the violent film. In fact, there was no significant change in GSR in either group throughout the whole experiment (only a specific contrast turned up significant for this, and even that was a pretty small effect). In other words, one might argue that there is no clear GSR change evoked by their "violent" stimulus. So if there is no effect to begin with, how can one group possibly be desensitized?


Above, I reviewed three reasons for doubting that this study has demonstrated a desensitizing effect of violent video games. The question addressed by this research - do violent video games desensitize people to violence - is an important one, but this study alone does not unequivocally answer this question.

It's also important to consider the practical aspects of these studies. For example, if the data had gone exactly the opposite direction - in other words, if the violent film increased the HR and GSR of violent VGPs relative to non-violent VGPs - would the authors have suggested that video games are good for you? No. In fact, the study is framed in such a way that any difference from "normal" (i.e., the group playing non-violent video games) will likely be viewed as deviant.

And then there are yet other important questions that haven't even been asked. Is desensitization fundamentally different from any other kind of habituation? Is it any more dangerous or long lasting than the effects of viewing violence in Hollywood movies, or on the nightly news? And, most critically, does desensitization have a causal relationship with aggressive behavior?

Related Posts:
Review of Carnagey, Anderson, and Bushman (Terra Nova blog)
Video Games - Mental Exercise or Merely Brain Candy?
Mind Games: Humans, Dolphins and Computers
Intelligent Adaptive Toys
Review: Everything Bad Is Good For You


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