Acute stress shifts third party intervention from punishing the perpetrator to helping the victim

Being stressed by witnessing injustice may prime your brain toward altruism, according to a study published in the journal PLOS Biology by Huagen Wang of Beijing Normal University and colleagues.

Punishing others requires more cognitive effort than helping them. Research shows that when witnessing an act of injustice and under stress, people tend to behave unselfishly, preferring to help the victim rather than punish the perpetrator. This is consistent with theories suggesting that different brain networks govern intuitive, quick decisions and deliberate, slow decisions. However, until now it was unclear how exactly the bystander's brain makes decisions to help or punish in stressful situations.

To better understand the neural processes that govern third-party intervention in cases of injustice, Wang and colleagues recruited 52 participants to perform a simulated third-party intervention task in an fMRI (functional magnetic resonance imaging) scanner. Participants watched someone decide how to distribute a monetary reward between themselves and another character who had to passively accept the offer.

The participant then decided whether to take the money from the first character or give the money to the second. About half of the participants immersed their hands in ice water for three minutes right before starting the task to induce stress.

Acute stress influenced decision making in situations of extreme injustice, in which the participant watched as someone took most of the money that should have been shared with another person. The researchers observed greater activation in the dorsolateral prefrontal cortex (DLPFC)—a brain region typically associated with thought and decision making—when stressed participants chose to punish the offender. Computer modeling has shown that acute stress reduces punishment bias, making a person more likely to help a victim.

The authors say their results suggest that punishing others requires more thought, cognitive control, and calculation than helping the victim. These results are consistent with growing evidence that people under stress tend to act more cooperatively and generously, perhaps because they devote more of their cognitive resources to deciding to help the victim rather than punish the offender.

The authors add: “Acute stress shifts third-party intervention from punishing the perpetrator to helping the victim.”