For over half a century the field of social psychology has been dominated by the idea of the bystander effect. This phenomenon suggests when scenes of aggression or violence unfold in public spaces individuals not involved are unlikely to offer help or intervene, especially when more bystanders are present. A new study, analyzing the largest number of real-life incidents caught on CCTV ever examined, is challenging this long-held proposition, finding bystanders actually do intervene in the vast majority of violent incidents that unfold in public spaces.

The bystander effect, as a social psychology theory, was largely spawned after the infamous Kitty Genovese murder in 1964. The story tells of a young woman murdered one night on the street outside a large apartment building in New York City. It was reported that 38 people saw or heard the attack, and strikingly, not one of those witnesses went to her aid or even contacted the police.

Two social psychologists, John Darley and Bibb Latane, soon became interested in the story, and the duo subsequently embarked upon a series of experiments that formed the backbone of many well-known psychology theories. The bystander effect assumes when people inhabit public spaces they are more likely to keep to themselves and less inclined to intervene in situations of aggressions involving others. And a phenomenon called diffusion of responsibility suggests the more people around in an instance of interpersonal violence, the less likely it is any one person will step up to intervene.

While the bystander effect has been effectively replicated many times in laboratory experiments it is unclear whether this behavioral trend actually translates into real-world environments. Even the story of Kitty Genovese has turned apocryphal, with recent study revealing the event was significantly misreported. It turns out a lot fewer than 38 people witnessed the murder, and their inactivity was greatly overstated, with reports the police were actually clearly called at the time by witnesses.

Utilizing increasingly sophisticated and widespread CCTV video systems found in cities all over the world, an international team of researchers set out to investigate whether the bystander effect is as prominent a phenomenon as social psychologists would expect. Video data was examined from 219 aggressive public conflicts spanning three different cities (Amsterdam in The Netherlands, Lancaster in the United Kingdom, and Cape Town in South Africa).

The results were striking. In 91 per cent of situations a bystander, or multiple bystanders, intervened in the public conflict. The interventions were as forthright as a bystander physically getting in between the two aggressors, or more general kinds of gesturing to get an antagonist to calm down.

Contradicting the classic idea of the bystander effect even further, the research found a victim was more likely to receive help if a greater number of bystanders were around. Interestingly, the rates of intervention were the same across all three cities, with the researchers suggesting this behavioral trait is universal and transcends certain local cultural norms.

"According to conventional wisdom, non-involvement is the default response of bystanders during public emergencies," explains Richard Philpott, lead author on the new study. "Challenging this view, the current cross-national study of video data shows that intervention is the norm in actual aggressive conflicts. The fact that bystanders are much more active than we think is a positive and reassuring story for potential victims of violence and the public as a whole. We need to develop crime prevention efforts which build on the willingness of bystanders to intervene."

This research is not alone in suggesting bystanders are not as passive in public conflicts as previously assumed. A 2017 study, for example, examining hundreds of police case reports, revealed around 75 percent of all public assaults resulted in interventions at the time from at least one bystander.

The new study doesn't completely debunk the phenomenon of the bystander effect, but instead suggests a certain separation between the results of social psychology experiments conducted in laboratory environments, and real-world behaviors.

"According to conventional wisdom, there is an epidemic of bystander non-involvement during public emergencies," the researchers write in the conclusion to the new study. "Challenging this view, the current cross-national study of video data shows that intervention is the norm in actual aggressive conflicts, with more populated settings providing a greater likelihood that someone helps. This is reassuring for potential victims of violence, the public as a whole, and may inform crime preventive efforts to make use of the already very active bystanders."

The new study was published in the journal American Psychologist.

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