Bullies and their victims show different patterns of brain activity to emotional faces

An estimated one quarter to one half of adolescents will at some point either be a victim of bullying, or engage in it — or both. Whether you're on the receiving end, or dealing it out, there are all kinds of associated negative implications for mental health and well-being, including distress, depression and anxiety.

"This highlights an important need to understand the predictors of bullying and victimisation, in order to identify ways to reduce these experiences in adolescents," write the researchers behind a new study, published in Social Cognitive and Affective Neuroscience. And this research has revealed one such factor: both bullies and victims show differences in the brain's response to angry and fearful faces.

Johnna Swartz at the University of California, Davis and her colleagues studied 49 adolescents, aged 12 to 15 years old, who were recruited from the local community.

They first reported on their experiences of "relational bullying" (either as bully or victim) over the past 12 months. This is a form of non-physical bullying that involves damaging an individual's social standing and relationships. It might entail excluding a child from social activities — like a party or a group chatting at a lunch table — or spreading gossip or rumours about them. Next, the participants were shown a series of images of faces chosen to signal fear, anger or happiness while their brains were scanned using fMRI.

The team found clear relationships between patterns of activity in the amygdala (a region of the brain involved in detecting threats) and scores on the relational bullying questionnaire.

A combination of above-average amygdala activity to angry faces and low activity to fearful faces was associated with engaging in more bullying behaviour. Meanwhile, greater amygdala responsiveness to angry faces and/or higher responsiveness to fearful faces was linked to more experiences of being a victim of this type of bullying. The scans also suggested that increased activity in the rostral anterior cingulate cortex (rACC) in response to fearful faces was associated with less bullying behaviour.

"These results suggest that relational bullying and victimization are related to different patterns of neural activity to angry and fearful faces, which might help in understanding how patterns of social information processing predict these experiences," the researchers write.

Exactly how those patterns may play out is not yet clear, but the researchers make some suggestions.

When it comes to bullying behaviour, adolescents with a strong amygdala response to angry faces may be biased towards interpreting peers in ambiguous social situations as being hostile, they suggest. Low reactivity to fearful faces, meanwhile, may relate to a decreased ability to perceive or process someone else's distress, which could lead to reduced empathy or perspective-taking. This combination might then make an individual more prone to bullying.

Meanwhile, adolescents with stronger responses to either fearful or angry faces, or both, may be more likely to avoid their peers, leading to increased rejection and raising the chances of victimisation, the researchers suggest.

What about the rACC findings? This region is involved in integrating social and emotional information. So perhaps, Swartz and her team speculate, heightened activity in response to fearful faces could reflect further processing of someone else's distress, which may promote empathy, and reduce the likelihood of bullying.

The study does have several limitations. The sample size was relatively small. In fact, the results should be considered preliminary until they are replicated in a bigger sample, the researchers note. Also, as they didn't measure levels of empathy, for example, the proposed explanations for the patterns in the data will need to be investigated in future studies. Then there's the fact that this was a cross-sectional study. Perhaps differences in patterns of amygdala activity resulted from experiences of bullying or being bullied

More work is clearly needed to explore these questions. But given the scale of the problem, there's an urgent need for such work.

As the researchers themselves argue, "If these effects are replicated and extended to longitudinal research in the future, they will help to elucidate how biased patterns of social and emotional processing may increase risk for bullying and victimization in adolescents and could lead to more tailored intervention approaches."

Further reading

– Amygdala activity to angry and fearful faces relates to bullying and victimization in adolescents 

About the author

Emma Young (@EmmaELYoung) is a staff writer at BPS Research Digest