A crowded street outside in Boston
A crowded street in central Amsterdam. Surveillance footage showed that people on busy streets are more willing to intervene in a volatile incident. Margriet Faber/AP

A new study uses camera footage to track the frequency of bystander intervention in heated incidents in Amsterdam; Cape Town; and Lancaster, England.                            

It’s one of the most enduring urban myths of all: If you get in trouble, don’t count on anyone nearby to help. Research dating back to the late 1960s documents how the great majority of people who witness crimes or violent behavior refuse to intervene.

Psychologists dubbed this non-response as the “bystander effect”—a phenomenon which has been replicated in scores of subsequent psychological studies. The “bystander effect” holds that the reason people don’t intervene is because we look to one another. The presence of many bystanders diffuses our own sense of personal responsibility, leading people to essentially do nothing and wait for someone else to jump in.

Past studies have used police reports to estimate the effect, but results ranged from 11 percent to 74 percent of incidents being interventions. Now, widespread surveillance cameras allow for a new method to assess real-life human interactions. A new study published this year in the American Psychologist finds that this well-established bystander effect may largely be a myth. The study uses footage of more than 200 incidents from surveillance cameras in Amsterdam; Cape Town; and Lancaster, England.

Researchers watched footage and coded the nature of the conflict, the number of direct participants in it, and the number of bystanders. Bystanders were defined as intervening if they attempted a variety of acts, including pacifying gestures, calming touches, blocking contact between parties, consoling victims of aggression, providing practical help to a physical harmed victim, or holding, pushing, or pulling an aggressor away. Each event had an average of 16 bystanders and lasted slightly more than three minutes.

The study finds that in nine out of 10 incidents, at least one bystander intervened, with an average of 3.8 interveners. There was also no significant difference across the three countries and cities, even though they differ greatly in levels of crime and violence.

Instead of more bystanders creating an immobilizing “bystander effect,” the study actually found the more bystanders there were, the more likely it was that at least someone would intervene to help. This is a powerful corrective to the common perception of “stranger danger” and the “unknown other.” It suggests that people are willing to self-police to protect their communities and others. That’s in line with the research of urban criminologist Patrick Sharkey, who finds that stronger neighborhood organizations, not a higher quantity of policing, have fueled the Great Crime Decline.

But how does this study generate findings that are so at odds with such widely held norms? The researchers point out that the bystander effect was reinforced by research that took place in laboratory-like experiments, which put bystanders in situations that do not approximate real life. Surveillance footage shows not what people guess they’d do in an experimental setting, but what they actually do in the real world.

This high rate that bystanders intervene may seem somewhat surprising given the high personal risks they take. But, such a willingness to intervene is actually more in line with the “better angels of our nature.” Human beings are social animals and cooperative creatures: We empathize, forge bonds, and build communities. Instead of putting our heads down and looking away, we are much more likely to intervene when necessary, even at risk to ourselves—to deter bad behavior and protect others.  

CityLab editorial fellow Claire Tran contributed research and editorial assistance to this article.

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