Teens who bully their peers tend to display a different pattern of brain activity in response to certain facial expressions, according to new research published in Social Cognitive and Affective Neuroscience. The findings shed light on the neurological underpinnings of bullying behaviors and could help lead to new interventions to combat bullying.

“Bullying is fairly common during adolescence, with about 25-50% of teenagers in the U.S. reporting that they have bullied or been a victim of bullying,” said study author Johnna R. Swartz, an assistant professor at the University of California, Davis.

“We also know that being a bully or victim of bullying is associated with poor mental health. I was interested in examining how measures of brain function relate to bullying or being a victim of bullying so we could better understand which factors may contribute to higher likelihood of these outcomes.”

Swartz and her colleagues were particularly interested in a brain region known as the amygdala, which plays a key role in emotional processing and responding to threats.

The researchers used functional magnetic resonance imaging to examine amygdala activity in 49 adolescents as they completed an emotional face matching task.

They found that adolescents who reported engaging in more relational bullying behaviors (such as purposefully excluding a peer or spreading rumors) tended to display higher amygdala activity in response to angry faces and lower amygdala activity in response to fearful faces.

“Higher amygdala activity to angry faces could suggest that these teens are more sensitive to signals of anger from other people, while lower amygdala activity to fearful faces could suggest that their brains are less responsive to signals of distress, which could lead to lower empathy when bullying victims,” Swartz told PsyPost.

“The higher amygdala activity to angry faces could also lead teens to perceive more hostility in their social interactions, whereas the lower amygdala activity to fearful faces could lead to lower empathy, and this combination seems to be associated with more bullying behavior. These results can help us to understand what may make some teens more likely to bully their peers.”

The researchers also found that lower amygdala activity in response to angry faces and lower amygdala activity in response to fearful faces were both associated with lower levels of victimization.

But the study — like all research — includes some limitations.

“A major caveat of this study is that the design was cross-sectional, meaning that amygdala activity and the measures of bullying behavior were collected at the same point in time. This means it is unclear whether these patterns of brain activity may have led to increased likelihood of bullying, or whether being a bully leads to these changes in brain activity,” Swartz said.

“Future research could use longitudinal designs with measures across several occasions to test whether these patterns of brain activity predict bullying behavior, or whether engaging in more bullying behavior predicts changes in these patterns of brain activity over time.”

“If longitudinal research confirms that these patterns of brain activity predict increases in bullying behavior over time, results from this study could have implications for new ways to reduce bullying behavior in the future,” Swartz explained.

“For example, the finding that higher amygdala activity to angry faces predicts more bullying behavior suggests that training teens’ attention away from angry faces or teaching teens to interpret ambiguous facial expressions in less hostile ways could be potential methods for reducing bullying.”

“The more we understand about how patterns of brain activity and the way we process social cues relates to bullying and victimization, the better we will be able to intervene to reduce bullying and victimization in teens,” Swartz added.

The study, “Amygdala activity to angry and fearful faces relates to bullying and victimization in adolescents“, was authored by Johnna R. Swartz, Angelica F. Carranza, and Annchen R. Knodt.