It was not a planned experiment. But two Stanley Cup riots in the same city 17 years apart are resulting in what is almost certain to become a landmark study of social media's role in mob behaviour, police tactics and public response.
Thousands of tweets, photos and videos from people on the street, as well as live television coverage, mean people were watching the 2011 riot unfold in real time - unlike 1994 when news reports trailed the event.
As well as changing how the public witnessed the riot, social media in 2011 became a tool and platform for those involved, whether that was in bragging of their exploits on Facebook or using texts to tell acquaintances where looting was under way.
In 1994, police obtained search warrants to compel television stations to turn over riot footage. In 2011, the Vancouver Police Department has set up a channel for people to upload photos and videos in the hopes of prosecuting those who trashed property and looted businesses.
Some of the ways in which social media played a role:
As fuel: Social media "exacerbates" the mob mentality that drives a riot, says Christopher Schneider, assistant professor of sociology at the University of British Columbia's Okanagan campus. And the social media habit of photographing and broadcasting one's activities and whereabouts gives another push. "The law-abiding citizens who normally would get out of Dodge are sticking around because I want to be part of the action, and I'm going to prove it, so I'm going to take a picture of myself beside this burning cop car."
As a way to fight back: Even as the smoke was clearing, Facebook groups were forming to identify people who had smashed and looted the city and to galvanize early morning clean-up crews that featured students, parents and their children and a group from the First United Church homeless shelter. On Twitter, the hash tag #thisismyvancouver became a rallying cry for messages that decried the riot's violence and vandalism.
As a tool for police: For police, online posts and the public's videos and photographs are expected to play a significant role in identifying and charging those directly involved in the mayhem. Police can be expected to come down hard on people who bragged of their involvement to discourage the link between social media and future mass gatherings, Prof. Schneider said.
The mob mentality phenomenon, which sees people in crowds act in ways they wouldn't typically act on their own, has a parallel in cyberspace.
"This idea of a lack of accountability has carried over into social media and cyberspace - where people are posting, 'Hey, I robbed a store," Prof. Schneider said. "Facebook is a society of 600 million people, and there's this idea that, 'Hey, nobody's going to pay attention to my silly posting' - but they are."
Social media may also have played a role in how police responded to Wednesday's riot, Prof. Schneider said, noting that police would have expected that every move they made would be caught on camera. Early police response may have been muted in part because of a positive experience in the 2010 Olympics as well as memories from 1994, when police were slammed for being too tough on protesters, he said.
In a blog post Thursday, Alexandra Samuel, director of the social and interactive media centre at Emily Carr University, warned of the dangers of "citizen surveillance," citing potential risks such as informants in authoritarian states tracking tweets or posts critical of government.
Editor's note: An earlier version of this story incorrectly quoted Professor Christopher Schneider as saying Facebook has six million users. The correct quote states Facebook has 600 million users. This version has been corrected.