Does city life make us more or less likely to be a Good Samaritan when we observe someone in peril? When Raz Chan tackled the carjacker at Main and Broadway, he didn't pause to think. He heard a woman screaming, then an eerie silence fell over the normally busy corner, people frozen in the mid-afternoon sun. One of his students darted ahead and started hauling a scruffy young man back out of the open window of a black Subaru. And then, suddenly, Chan had the guy pinned to the ground. He'd never done anything like this. It's true he teaches Brazilian jiu-jitsu, self-defence, kickboxing, and other martial arts, and he's escorted a few unruly people out of classes. But now, all his training kicked in. He kept giving Dustin MacDonald, 24, instructions on what to do and not to do; he put him face down in a pain compliance hold that made it impossible to move without feeling like his arm would break. Chan didn't let himself get distracted by the crowd that gathered, but stayed focused until police and firefighters arrived. They thought it was amusing that anyone would try to commandeer a vehicle across from a martial-arts studio. It didn't seem funny to Chan: he knew that he and his students, who had just come out to get lunch at the end of a training session, had put themselves in danger. The Gracie Barra school is just up the hill from the Downtown Eastside; Chan's student, Matthew McKay, grabbed MacDonald without knowing where his hands were or whether he had a weapon or a needle. It could have gone very wrong. "When we got to statements after, our hands were starting to shake," says Chan, 45, as he sits back on the leather couch in the basement where the club functions, a few weeks after the incident. What really gives pause is what propelled Chan to act at all. And whether in the same situation it would move the rest of us as well. We like to imagine we could be heroic when the time comes. But an overwhelming body of research in psychology and sociology over the last half-century demonstrates that not everyone leaps into danger, even when that danger is relatively small. And a lot of the evidence suggests that the tendency to hang back is particularly high in cities. That's a warning for Vancouver. We're already home to demographic forces-our neighbourhoods' unusually high mix of ethnic, age, and economic groups; our history as a city built on perpetual waves of newcomers-that make it hard to connect and watch out for each other. Whether we welcome that reality or not, it does create social barriers seen less in small towns. Plus, we keep piling on density. Studies make it clear that the higher a neighbourhood's density, the less social control residents exert over negative events around them.   In March 1964, Kitty Genovese was stabbed to death in New York by a man who followed her home from a parking lot at 3 in the morning. At first, her death generated only small items in the local papers. But two weeks later, the New York Times reported that 38 people who lived in buildings around the scene of the murder saw her being stabbed, heard her screaming, yet did nothing. Much of the research about the role of neighbours and bystanders has sprung from this single incident; Genovese's death, which is routinely cited in psychology textbooks, became a symbol for the evils of big cities (in contrast to the then-booming suburbs, which were idealized). It became, as one set of British scholars wrote, "a kind of modern parable-the antonym of the Good Samaritan. Whereas the Good Samaritan parable venerates the individual who helps while others walk by, the story of the 38 witnesses in psychology tells of the malign influence of others to overwhelm the will of the individual." The murder generated a whole stream of research into what has been termed the "bystander effect"-the degree of likelihood that onlookers will take action if they think someone is ill or being attacked. Repeated experiments have shown that people who think they are the only witness to someone choking to death or being assaulted will intervene almost instantly. But if they believe others are witnessing the same thing, they respond more slowly-or may do nothing at all. That, combined with research on whether people are more likely to perform simple acts of helping in urban or rural settings, has convinced many that cities are cold, cruel places-a sentiment reinforced by the media. In the past couple of years, the bystander effect was mentioned when reporters wrote about people in New York who walked past the corpse of a homeless man for half a day, did nothing while a woman at Metrotown screamed that her purse had been stolen, and sat silent as an elderly man was robbed on the subway in Toronto. We imagine we could be heroic when the time comes. But research demonstrates that not everyone leaps into danger, even when that danger is relatively small. And the tendency to hang back is particularly high in cities Yet people in cities break that stereotype every day. "In neighbourhoods that are cohesive and connected, people know each other, feel ownership of their space, and know when something unusual is happening, and are more likely to act," says Kathy Coyne, who teaches in Capilano University's Community Leadership and Social Change program. Brent Granby has lived in one of Vancouver's densest neighbourhoods, the West End, most of his life, raising a family there. He's never had to try to stop a stabbing or a break-in or an assault. But he's part of an extended network of long-established residents who will speak up to help preserve social order in all the little ways. They have the sense that it's their territory, and they'll defend a certain standard of civility. "My experience is that, if someone on the bus is doing something inappropriate and one person steps up and does something, others will support that." That's even though intervening carries real dangers, especially in the Lower Mainland, with its unhoused populations of sick and desperate, and its proliferation of gangs. Rachel Davis was shot to death 10 years ago trying to break up a fight outside a Gastown nightclub. Robert Mackay (see "Action Figure," left) tried to stop a mob of rioters from smashing the windows at The Bay during the Stanley Cup riots and got a beating for his troubles. When two drivers started brawling outside the Aquatic Centre a few years ago, a bystander tried to intervene by putting up his hand. One driver punched him, then continued after the other. Yet Chan and his students jumped in to tackle the carjacker. Robert Mackay got some protection from two young men who braved the mob to help him. One of Chan's friends confronted a man who was harassing an elderly woman collecting bottles in an alley. Perpetual neighbourhood activist Eileen Mosca and her husband went out in front of their Commercial Drive-area house to stop a group of people from beating up a woman who'd just come out of a party they were all at. A cluster of bystanders took down a man last year who stabbed a woman in a 7-Eleven in the West End, holding him until police arrived. Passengers stopped a man from attacking people on the SkyTrain a couple of years ago. Vancouver police say they see dozens of actions like this every year.   Few people understand the subtler factors that prompt some to intervene, others to stand by. As critics of the Genovese parable have noted, sometimes the issue is not whether to act. "One of the challenges is to make sense of what's actually going on," says UBC business professor Karl Aquino, who studies moral decisions and bystander behaviour. "The initial hesitancy is often in just understanding the situation." Later accounts of the Genovese attack concluded that many people weren't witnesses at all. The two (not three, as first reported) attacks took place out of their line of vision. Even what they could see was confusing. She was kneeling and the man was kneeling. A neighbour yelled out of the window and the man went away. Genovese stood up and continued slowly down the street. (Her attacker came and stabbed her again in a stairwell out of view.) Someone did call the police, although people in that neighbourhood generally didn't bother-the area had a loud bar, and police had demonstrated they had little interest in the mayhem it was causing. Context matters as well. Dozens of bystander-effect experiments have shown that people are more likely to intervene if victims and witnesses share a social-identity group-if they're familiar in some way. Bystanders are also propelled to act by their own self-image. If they see themselves as helping, caring, moral people, they'll move into action. More recent studies show that people can also be coached to intervene when they see someone is being bullied, assaulted on a date, or beaten by a partner. If they get training on how to interpret what they're seeing and how to intervene without putting themselves in danger, they're more likely to step forward. "We can be influenced into action," says Aquino. And finally, a novel Canadian study about who is more likely to show bravery indicates there's a general attitude to life that prompts some to act. In most ways, they're pretty much like everyone else. But in one area of personality testing, they display a difference: they have an unusual belief that they have the power to transform bad events into good ones. It's happened in their lives already and they're optimistic it can happen again. "When they're faced with negative situations, they have learned to look at that negative and see an opportunity for something else," says Jeremy Frimer, a University of Winnipeg psychology professor who worked with UBC prof Larry Walker on his 10-year study of the phenomenon, outlined in a 2010 academic paper. Their silver-lining approach is the opposite of what a lot of people do-a way of thinking called contamination in the psychology world (and "whining" in the regular one), whereby something good happens, yet they transform it in their own minds into a negative. By contrast, "Heroes tended to take bad things and find something good in them." There's a general attitude to life that prompts some to act. In most ways, they're pretty much like everyone else. But in one area of personality testing, they display a difference Raz Chan fits into many of the predictive categories. Growing up, the soft-spoken man was one of the few Chinese kids in his neighbourhood. That made him an outsider. And his family struggled. His father, whose grandfather had immigrated to Canada to work on the railroad, had some big failures: he tried to run a restaurant and that flopped; the family didn't have money or a vacation for decades. But his father went on to start a sprout-growing business, and he now supplies half of Manitoba. A story of triumph over adversity. The once-skinny kid (six feet, 130 pounds) went on to become an accountant, a property manager, and then the world champion in Brazilian jiu-jitsu after taking the plunge into full-time martial-arts competitions and fitness training. Along the way, he moved to Vancouver, which manages to be both a big city and, as it was on that August day, a small town. After Chan's intervention made the news, his friend Julie called to tell him the strangest part of the whole thing for her: she knew the woman in the car. Julie connected Chan and the driver, who came down and talked about taking some self-defence classes. Getting to know each other helped him take yet another step away from the bad, toward the good, just as he'd done immediately after his unpremeditated tackle. "That night, I took a nice walk along the ocean to calm down." Now that he's processed the whole incident, would he still have done it? Oh yes. Hopefully, he can execute the tweaks the Abbey needs.