In the mid-20th century, the Western academic community looked at the Holocaust with a mix of horror and disbelief. The question of how it all happened—and what it all means—dominated moral philosophy and the social sciences. New work began to center on the concept of diffused responsibility, the long-held and philosophically well-supported idea that a person’s sense of moral responsibility is weakened if they believe a moral burden is shared.
Social scientists began to look for empirical evidence of this phenomenon, with mixed success. The two most well-known examples of studies that were used to document the existence of diffused responsibility—the Milgram experiment and the Stanford Prison Experiment—were memorable as performance art, but too compromised to function very well as scientific experiments. Also illustrative of diffused responsibility was the heartbreaking story of the 1964 murder of Kitty Genovese, who was said to have been slowly killed within earshot of 38 witnesses (none of whom bothered to call the police); the real story is much more complicated than that, though if you’re looking for anecdotes illustrating public indifference towards human suffering the front page of your local newspaper will probably do just fine.
In an upcoming paper in NeuroImage, Carnegie-Mellon neuroscientist Mina Cikara takes a different tack by looking at how the brain handles the diffusion of moral responsibility that takes place in group competition settings. Her findings, though very small-scale and preliminary, are stunning:
“We tested [a] hypothesis in an fMRI experiment in which (i) participants performed a competitive task once alone and once with a group; (ii) spontaneous self-referential processing during competition was indexed unobtrusively by activation in an independently localized region of the medial prefrontal cortex (mPFC) associated with self-reference; and (iii) we assessed participants' willingness to harm competitors versus teammates. As predicted, participants who showed reduced mPFC activation in response to descriptions of their own moral behaviors while competing in a group were more willing to harm competitors. These results suggest that intergroup competition (above and beyond inter-personal competition) can reduce self-referential processing of moral information, enabling harmful behaviors towards members of a competitive group.”
This doesn’t prove the existence of diffusion of responsibility; for most of us, history and life experience are proof enough. But it does begin to provide neurological context for our behavior, and future studies may help us unpack our human tendency to behave badly when we believe we have each others’ support.