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Friday, September 19, 2014

Do violent movies cause aggression? The answer may depend

The debate over whether violent movies contribute to real-world mayhem may have just developed a wrinkle: New research suggests they might enhance aggression only in those already prone to it.


Using PET scanners to peer into the brains of volunteers watching especially bloody movie scenes, researchers determined that the way a viewer’s brain circuitry responds to violent video depends upon whether the individual is aggressive by nature. The study was published Wednesday in PLOS One.

“Just as beauty is in the eye of the beholder, environmental stimuli are in the brain of the beholder,” said Nelly Alia-Klein, the study’s lead author and an associate professor at the Friedman Brain Institute and the Icahn School of Medicine at Mount Sinai Hospital in New York City.

To test the importance of personality, Alia-Klein and her colleagues rounded up 54 healthy men, some of whom had a history of getting into physical fights, while the others had no history of aggression. The researchers scanned the volunteers three times: doing nothing, watching emotionally charged video and viewing a violent movie.

“It wasn’t the whole [violent] movie,” Alia-Klein said, “just the violent scenes, one after another after another.” Along with the brain scans, the researchers monitored blood pressure and asked about the viewers’ moods every 15 minutes.

While the two groups of men responded similarly when watching the emotional video, their brain scans and blood pressure readings were strikingly different as they viewed the violent scenes. The non-aggressive men’s blood pressure rose and the orbitofrontal cortex, an area of the brain involved in impulse control and decision making, sparked brightly.

The aggressive men’s brains were much quieter and their blood pressures either stayed the same or in some cases dropped a little.


To Alia-Klein, the blood pressure readings meant that the aggressive men were not disturbed by the violent scenes they were viewing. And the lack of activity in the orbitofrontal cortex meant “they weren’t engaging the part of the brain that would say, ‘this is bad.’ It could be because this is congruent with their personalities, that it’s part of their ‘normal.’”

She speculates that the impact may be to enhance the aggression that is already there. “At the right time, when they become violent, they may act out some of the ideas they have seen,” Alia-Klein said. “The movies may offer them ways to kill or aggress.”

Dr. Marco Iacoboni, a brain researcher unaffiliated with the new study, said the findings make a lot of sense.

“This is a nice correlation between the aggression and blood pressure,” said Iacoboni, a professor in the Department of Psychiatry and Behavioral Sciences and director of the Transcranial Magnetic Stimulation Lab at the Ahmanson-Lovelace Brain Mapping Center at the David Geffen School of Medicine at UCLA. “When they see a violent movie their blood pressure doesn’t go up like the quiet guy’s does. It’s almost like they feel at home.”

And the calm orbitofrontal cortex may mean that these aggressive men aren’t able to rein themselves in when angry.

“So if you make me mad I control myself because I am able to do that,” Iacoboni said. “But someone else might be less able to control their emotions and that most likely would lead to aggression.”

The new study “takes an important step forward by documenting experimentally the important variability of our responses to violent media,” said Dr. Brian A. Primack, an associate professor of medicine and pediatrics and director of the Program for Research on Media and Health at the University of Pittsburgh. “It makes sense that different people who experience violent media — such as movies or video games — will respond differently to those stimuli.

“Some people are apparently inspired by or assisted in engaging in antisocial acts, while others may instead develop anxiety or fear responses, and still others may have very little change in mood or inclination.”

Courtesy: NBC News