Bullies love to bully

Nov 9 2008

According to American scientists brain scans show that bullies enjoy their behaviour.

A new study by researchers at the University of Chicago has found that the brain scans of young, aggressive bullies suggest they may actually enjoy seeing others in pain.

The researchers from the University of Chicago used functional Magnetic Resonance Imaging (fMRI) scans of eight 16 to 18 year-old boys with aggressive conduct disorder and compared them to eight matched adolescents without conduct disorder.

The scans showed a disturbance in normal levels of empathy and increased activity in an area of the brain associated with rewards when the aggressive boys watched a video clip of someone inflicting pain on another person, but the control group did not have the same response.

Lead researcher Dr. Jean Decety, a professor in psychology and psychiatry at the University of Chicago, says this is the first time that fMRI scans have been used to study situations that could otherwise provoke empathy.

Earlier this year Decety and his colleagues found from fMRI scans on 7 to 12 year-olds showed that they are naturally empathetic toward people in pain but this latest research shows that this natural empathetic impulse may be disrupted in ways that increase aggression in some young people who are prone to bullying and other aggressive behaviours.

Dr. Decety says 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 suggests that they enjoyed watching pain.

Dr. Decety says the youths were shown video clips in which people suffered pain accidentally, such as when a heavy bowl unintentionally was dropped on their hands, and intentionally, such as when a person stepped on another's foot.

The researchers expected the test subjects to be emotionally cold to the events, but instead they registered a high level of arousal and they say their revelation warrants more research to determine whether the reactions indicated enjoyment at seeing others in pain.

Dr. Decety says the research will lead to a better understanding of how to deal with juveniles who are aggressive and violent and will also help identify strategies for dealing with young people who are at risk of growing up to be antisocial or even psychopathic.

Co-author Dr. Benjamin Lahey says the finding will lead to ways to help at risk youngsters self-regulate their emotions but he acknowledges past difficulties with the approach.

Dr. Lahey says a system of non-punitive punishments for aggressive behaviour and rewards for non-aggressive behaviour may be another approach.

The research is published in the current issue of the journal Biological Psychology and was supported by the National Science Foundation.