Investigators, led by Vincent P. Mathews, M.D., professor of radiology, concluded that media violence exposure may be associated with alterations in brain function whether or not prior aggressive behavior is involved.
This study builds on earlier research that showed exposure to violent media affects the brains of youths with aggressive tendencies differently than the brains of non-aggressive youths. The preliminary results, released in December 2002, showed less brain activity in the frontal lobe of youths with an aggression disorder as they watched violent video games.
In the current study, functional magnetic resonance imaging (fMRI) was used to show activity in the brain when study participants performed a concentration test called a counting Stroop task.
Participants were shown a number that is repeated and they are to respond to the number of times they saw the number. For example, if participants are shown "222" the correct answer would be "three" because the number "2" is shown three times. Previous research has shown that Stroop tasks require participants to concentrate by using the part of the brain responsible for decision-making and self-control.
Two groups each of 14 boys and five girls were involved in the study. All the members of one group had a chronic pattern of violent behavior and had been diagnosed with disruptive behavior disorder (DBD). The second or control group had no history of behavior problems.
Members of both groups had been exposed to different amounts of violent media in their everyday lives over the past year. Fifty-eight percent of the DBD group was determined to have high exposure compared to 42 percent of the control group. Media violence exposure was defined as the average amount of time per week that the adolescents watched television or played video games depicting human injury.
The fMRI brain images revealed that members of the control group with high prior exposure showed less activity in the frontal cortex of the brain, an area linked to attention and self-control. All of the DBD group, even those without high violent media exposure, showed a similar pattern of frontal cortex activity. Less activity in the frontal cortex has been linked to poorer self control and attention problems.
In contrast to the DBD group and the control group with high media violence exposure, the members of the control group without high violent media exposure showed more frontal cortex activity.
"This observation is the first demonstration of differences in brain function being associated with media violence exposure," said Dr. Mathews. "We found that individuals in the control group with high media violence exposure showed a brain activation pattern similar to the pattern of the aggressive group."
William Kronenberger, Ph.D., associate professor in the Department of Psychiatry, who has collaborated with Dr. Mathews on these ongoing studies, cautioned that more research is needed before conclusions can be drawn that media violence exposure causes the brain activation differences.
He warned that any association between media violence exposure and brain functioning should be taken seriously while this additional research is conducted.
"We found high rates of exposure to violent television and video games in teens, but we are just beginning to explore the possible implications of this exposure for brain and behavioral development," said Dr. Kronenberger.
"There are myriad articles showing that exposure to violent TV especially causes individuals to be more aggressive. We are studying the neurological and self-control processes that underlie the aggressive behavior."
The research was funded by the Center for Successful Parenting.