WEDNESDAY, Aug. 9, 2006 (HealthDay News) -- Playing violent video games, even for only 20 minutes, desensitizes people to real-world violence, new research contends.
"We found that the subjects who played violent video games for 20 minutes had lower physiologic responses when they watched videos of real-life violence," said Nicholas Carnagey, who conducted the research while a psychology instructor at Iowa State University in Ames.
He explained that these lowered physical responses meant the person felt less emotional upset when viewing real-life brutality.
Prior studies have reported a correlation between exposure to violent video games and desensitization to real violence. But Carnagey's team say theirs is the first to expose subjects to video games and then measure their physiologic reactions to real-life violence through heart rate and galvanic skin response, which evaluates perspiration.
As heart rate and perspiration increase, so does emotional arousal, said Carnagey, who is now a professor at Wake Forest University.
Released online ahead of print in the Journal of Experimental Social Psychology, the study included 257 college students (124 men and 133 women) who were tested before and after playing violent or non-violent video games for 20 minutes. Violent games included Carmageddon, Duke Nukem, Mortal Kombat and Future Cop. Non-violent games included Glider Pro, 3D Pinball, 3D Munch Man and Tetra Madness.
All of the participants had similar heart rates and other signs of arousal before exposure to real-life violence, which included videotaped shootings, prison fights and police confrontations.
"The only time we saw physiologic differences [among participants] was while they were watching real-life violence," Carnagey said.
The people who played violent video games for 20 minutes had lower galvanic skin responses (lower perspiration) and heart rates while watching the real-life footage. "A lot of other studies on exposure to violent video games indicated that we would find this [desensitization], but it surprised us that only 20 minutes of exposure was enough to show this effect," Carnagey said.
Translated to the real world, these signs of lower emotional upset may mean a person is more desensitized to violence. He or she may also be less able to identify violence and less likely to help victims of violence, Carnagey explained.
The findings could raise a red flag for parents.
Even though the study targeted college students, "there's no doubt that these results apply to younger children, and there's every reason to be concerned that the effects be may even greater in those under the age of 7 because these children don't distinguish very well between fantasy and reality," said pediatrician Dimitri A. Christakis, director of the Child Health Institute at the University of Washington, Seattle, and author of the book The Elephant in the Living Room: Make TV Work for Your Kids.
Researchers already know that exposure to violent media in many different forms leads to violence and aggression in the real world, but the mechanism for how this occurs is less well-known. The study suggests that desensitization -- defined by researchers as a reduction in emotion-related physical reaction to real violence -- may be a critical factor in that pathway.
The caution for parents is real, Christakis said. "Children are much more media-savvy at a much younger age than their parents were," he noted.
Many parents believe that violent games won't make their children more violent, but they might not be witnessing any increase in aggressive behaviors first-hand, he noted. The negative effects of video game exposure often infiltrate children's real-life games, Christakis said. "This increasing violence is mutually enhancing in a negative way," he warned, because "it reinforces violence in their own lives."
Much of the media children watch is laden with violence, Carnagey added. In G-rated movies and games, violence is often packaged in a "cute and friendly manner," the Iowa researcher noted.
And "as children grow older, they're exposed to ever more realistic and gory scenes," he said. "Parents might say, 'My child is not ready to see that yet,' but what does that comment mean? When would children be ready to see someone beheaded?"
This unintended desensitization from exposure to very violent media can have a real impact on children's development, according to the researchers.
"In real life, were not talking about a simple 20-minute exposure, were talking about exposure that's hours on end, day after day," Carnagey said. "Parents should be aware and active in their child's exposure to media. They should really think about what messages they're exposing their children to."
The study also raises some important questions for future research, including whether the effects of short-term exposure to violent games lingers, and what the cumulative effect might be of playing violent video games over days, weeks, and years.
For more on media violence and its effects on children, visit the American Academy of Pediatrics.