Repeated exposure to violent television programs and video games can make teenage boys behave more aggressively, according to a new study published online today in the journal Social Cognitive and Affective Neuroscience.
According to a press release, Dr. Jordan Grafman and colleagues at the National Institutes of Health’s (NIH) National Institute of Neurological Disorders and Stroke recruited 22 14- to 17-year-olds and showed each of them a series of violent clips.
The footage used was four-second segments from 60 different videos, each arranged in random order in three groups of 20 clips. The researchers note that the levels of violence in each scene was graded as either low, mild, or moderate, and none of the footage contained extreme acts of violence.
The subjects were asked to rate the level of each scene as either more or less aggressive as the previous clip, doing so by pressing a corresponding response button. During the survey, each of the teenagers were positioned in an MRI scanner, which collected data in regards to their brain functions during each of the videos.
Electrodes were also attached to the fingers of their non-dominant hand in order to gauge skin conductance responses, or SCR. According to the press release, SCR is used to measure sweat levels associated with emotional response to the external stimuli.
“Data from the SCR showed that the boys became more desensitized towards the videos the longer they watched them and also that they were more desensitized by the mildly and moderately violent videos, but not the ones that contained a low degree of violence,” the press release said, adding that the brain activation patterns of the teenagers “showed a similar effect.”
The researchers also noted that the greatest desensitization was uncovered in those young men who had the highest level of exposure to violent media in their day-to-day lives.
“The important new finding is that exposure to the most violent videos inhibits emotional reactions to similar aggressive videos over time and implies that normal adolescents will feel fewer emotions over time as they are exposed to similar videos,” Dr. Grafman said in a statement. “This finding is driven by reduced posterior brain activation and therefore the frontal lobe doesn’t react as it normally would.”
“The implications of this are many and include the idea that continued exposure to violent videos will make an adolescent less sensitive to violence, more accepting of violence, and more likely to commit aggressive acts since the emotional component associated with aggression is reduced and normally acts as a brake on aggressive behavior,” he added.
Only male subjects were recruited for the project, but Grafman and his colleagues point out that the “incidence rate of aggression” for girls in the 14 to 17 year old age group “is low and raises the questions of what brain mechanisms and autonomic differences are associated with this gender difference.”
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