The Neuroscience of Revenge

The famous serial killer Ted Bundy murdered 30 young women across multiple states. His victims had several things in common but perhaps the most striking was their similarity in appearance: physically attractive, young, brunette, long-hair parted down the middle. After Bundy’s arrest, it became clear that these victims were also remarkably similar to a woman that Bundy dated as a young man. This woman eventually dumped Bundy, which proved emotionally disastrous for the future murderer. Did this experience of rejection push Bundy along his homicidal path?

Although the motives of murderers are not always clear, the role of rejection in motivating aggression is well-established. In laboratory experiments in which participants are led to feel rejected, these ostracized individuals administer more harm to their rejecters (and even innocent people) than their accepted counterparts. We know many of the psychological processes that motivate such rejection-related aggression, but the brain mechanisms that promote post-rejection revenge are less well understood.

To better understand how the brain regulates aggressive responses to rejection, we conducted and published a new functional brain imaging study on this topic. In this study, 60 healthy young adults arrived at our MRI research center. These participants laid down inside of an MRI scanner and played a computerized ball-tossing game. The focus of the game was to simply toss a ball back and forth with two other partners and to imagine that the game was occurring in real life. After playing the game for several minutes, their two partners stopped throwing them the ball and tossed it to each other repeatedly while the participant watched. This seemingly innocuous form of exclusion elicited strong feelings of rejection. Several of the participants in this study spoke to me after exiting the MRI scanner, saying things like, “Did you see what those jerks did to me in that ball-tossing game?”

After this rejection induction, we gave participants the opportunity to get back at their rejecters. Specifically, they could choose the volume with which to repeatedly blast one of their rejecters with a very uncomfortable sound. The higher the volume, the greater the revenge. Participants completed both the ball-tossing task and the noise blast task while we measured the extent to which the various regions of their brain were more or less active.

Source: David Chester

When we examined the data from the rejection portion of the study, we focused on activity in a specific part of the brain: the ventrolateral prefrontal cortex (VLPFC). The VLPFC serves to inhibit our feelings of pain and distress. Social rejection is truly painful, and the VLPFC helps us suppress this aversive experience.

We found that the more that participants recruited the VLPFC during rejection, the more revenge they inflicted upon their rejecters. This suggests that the more that our brain effortfully inhibits the pain of rejection, the more that we seek to harm others. But why? To find out, we then looked at what the brain was doing during the noise-blasting revenge portion of the study. We observed that during revenge, participants recruited the reward circuitry of the brain, replicating previous work showing that revenge is truly sweet. We added this finding to the others in what we call a ‘mediation model,’ observing a sequence of events in which recruiting the inhibitory VLPFC during rejection predicted more reward activity during revenge, which predicted more revenge-seeking noise blasts.

Source: David Chester

These findings suggest that the more that we seek to suppress the sting of rejection, the sweeter we find revenge. This may be because we have fatigued our brain’s inhibitory abilities during rejection, resulting in an unrestrained reward response during revenge. This interpretation was supported by another finding from this study, in which we observed that people who tend to be chronically aggressive showed a de-coupling between the brain’s reward circuit and the inhibitory VLPFC during revenge. Such unrestricted reward activity in the brain may reinforce such aggressive behaviors and explain why some people tend to be consistently violent across time and situations.

How does this help us make the world a less violent place? Well, it fits with some of our other research, which shows that attempting to suppress the sting of rejection is a bad strategy. This suppressive approach fatigues our inhibitory resources and leaves our unholiest desires unrestricted. Instead of trying to tamp down these painful feelings, we should find ways to engage with them in a more mindful way. Indeed, our biology informs our psychology and suggests clear ways to break the rejection-aggression link.