By studying the footage from an unidentified UK city’s CCTV cameras, psychologist Mark Levine is finding that a number of theories about crowd psychology previously taken as gospel may be incorrect, including the bystander effect (sometimes referred to as the Kitty Genovese effect) and the idea that crowds are inclined to be unruly and violent.
Dr Levine persuaded the authorities in one British city to allow him to look at their CCTV footage of alcohol-fuelled conflict in public places. […] He analysed 42 clips of incidents that operators in a control room had judged had the potential to turn violent, though only 30 of them actually did so. He recorded gestures he labelled either “escalating”, such as pointing and prodding, or “de-escalating”, such as conciliatory open-handedness. […]
Judging the fight to begin with the aggressor’s first pointing gesture towards his target, the researchers found that the first intervention usually involved a bystander trying to calm the protagonist down. Next, another would advise the target not to respond. If a third intervention reinforced crowd solidarity, sending the same peaceful message, then a violent outcome became unlikely. But if it did not—if the third bystander vocally took sides, say—then violence was much more likely.
via Mind Hacks