Behavioral psychologists have known for quite some time that people are more likely to harm others when they're part of a group. A new study suggests that "mob mentality'" happens when we stop reflecting on our own personal moral standards.


People become more hostile when there's an 'us and them' scenario. Individuals in groups often exhibit behaviors that are contrary to their private moral standards. Studies have shown that, when people are in a group, they feel more anonymous, and that they're less likely to be caught. They also feel less accountable for a collective action.

But a new study by Mina Cikara and Rebecca Saxe offers a third factor: The suggestion that people in groups lose touch with their own morals and beliefs and become more likely to do things they would normally believe are wrong.


Anne Trafton from MIT New Office explains:

In a study that recently went online in the journal NeuroImage, the researchers measured brain activity in a part of the brain involved in thinking about oneself. They found that in some people, this activity was reduced when the subjects participated in a competition as part of a group, compared with when they competed as individuals. Those people were more likely to harm their competitors than people who did not exhibit this decreased brain activity. "This process alone does not account for intergroup conflict: Groups also promote anonymity, diminish personal responsibility, and encourage reframing harmful actions as 'necessary for the greater good.' Still, these results suggest that at least in some cases, explicitly reflecting on one's own personal moral standards may help to attenuate the influence of 'mob mentality,'" says Mina Cikara, a former MIT postdoc and lead author of the NeuroImage paper.

More at MIT News, including details about the experiment. Read the entire study: "Reduced self-referential neural response during intergroup competition predicts competitor harm."

Image: Hugo Jaeger—Time & Life Pictures/Getty Images .