Bullies enjoy inflicting pain on others

November 7th, 2008 - 5:23 pm ICT by IANS  

Washington, Nov 7 (IANS) Aggressive bullies actually enjoy inflicting pain on others, according to a new study of brain scans.Such scans showed that brain area associated with rewards was highlighted when the highly aggressive youth watched a video clip of someone inflicting pain on another person.

“This is the first time that fMRI scans have been used to study situations that could otherwise provoke empathy,” said Jean Decety, professor of psychology and psychiatry at Chicago University, who led the study.

“This work will help us better understand ways to work with juveniles inclined to aggression and violence,” he said. Benjamin Lahey, professor of psychiatry, co-authored the paper with graduates Kalina Michaslska and Yuko Akitsuki.

Researchers compared eight 16 to 18-year-old boys with aggressive conduct disorder to a control group of adolescent boys with no unusual signs of aggression, said a Chicago University release.

The boys with the conduct disorder had exhibited disruptive behavior such as starting a fight, using a weapon and stealing after confronting a victim.

The youth were tested with fMRI while looking at video clips in which people endured pain accidentally, such as when a heavy bowl was dropped on their hands, and intentionally, such as when a person stepped on another’s foot.

“The aggressive youth activated the neural circuits underpinning pain processing to the same extent, and in some cases, even more so than the control participants without conduct disorder,” Decety said.

“Aggressive adolescents showed a specific and very strong activation of the amygdala and ventral striatum (an area that responds to feeling rewarded) when watching pain inflicted on others, which suggested that they enjoyed watching pain,” he said.

Unlike the control group, the youth with conduct disorder did not activate the area of the brain involved in self-regulation (the medial prefrontal cortex and the temporoparietal junction).

The control group acted similarly to youth in a study released earlier this year, in which Decety and his colleagues used fMRI scans to show seven to 12-year-olds are naturally empathetic toward people in pain.

The scans showed that when the children saw animations of someone hurt accidentally, the same portion of the brain that registered pain when they are hurt also was highlighted upon seeing someone else hurt.

The results appeared in the current issue of Biological Psychology.

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