Virtual worlds, real science: epidemiologists, social scientists flock to online world

Science News,  Oct 27, 2007  by Brian Vastag

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Skeletons paved the cobblestone streets. Thousands had succumbed to the blood plague quickly, but others lingered--only to infect everyone they met. No one was safe. Warriors, mages, and healers all fell. Word spread, urging everyone to flee, but still the plague ripped through the world, creating a holocaust.

A hulking, serpentine blood god, Hakkar the Soulflayer, had sparked the epidemic. Attacked in his dungeon, the monster unleashed his final defense--a curse called corrupted blood. The curse infected the attackers and quickly spread to their companions like an ultra-virulent airborne virus. As adventurers fled the dungeon, they carried the illness back to their towns. Soon the plague even crossed into animals. Within days, the World of Warcraft--a hugely popular online adventure game--was devastated.

Although the death of a character in the World of Warcraft is a mere annoyance--the character disappears for a minute or two and then rematerializes--the plague proved unstoppable. Eric Lofgren was playing the game during the virtual outbreak in September 2005. "It was a big deal," says Lofgren, who at the time was an epidemiology student at Tufts University in Boston. "Early on, it wasn't clear how it spread or what was going on. Players attempted to heal other players ... not knowing that they were taking damage and indeed spreading the plague. There was a lot of confusion. A lot of people abandoned [the game] until it got sorted out."

It took Blizzard Entertainment, the Irvine, Calif., company behind World of Warcraft, nearly a week to stop the virtual plague. At that time the online Tolkeinesque world of swords and sorcery boasted 4 million subscribers (it now has 9 million). To enrich the game, the company's programmers had created Hakkar and made the monster so strong that players would have to band together to kill it. The programmers placed Hakkar in a remote dungeon and expected his blood curse to remain localized there. But they hadn't accounted for human behavior.

Instead of staying in the cave, infected players teleported to the towns. Soon, their virtual pets became infected--and contagious. Both man and beast spread the disease to densely populated areas, where weaker characters who contracted it died instantly. Computer-controlled characters such as shopkeepers also became infected, but didn't die. Along with the pets, these characters acted as silent carriers, virtual Typhoid Marys.

It turns out that Lofgren's adviser at Tufts, Nina Fefferman, specializes in computer modeling of infectious diseases. When Lofgren told her about the virtual chaos, she called Blizzard. Enticed by parallels between the virtual and actual outbreaks, Fefferman asked the company to preserve the plague data. "Their initial reaction was confusion," she says. "They said, 'This is a bug, we're worried about fixing it, we're not worded about logging data for you.'"

Minus Blizzard's help, Fefferman and Lofgren still learned enough from observing the outbreak, reading accounts on game-related Web sites, and interviewing players to publish a paper in Lancet Infectious Diseases this August. In it, they outline the potential of garnering valuable lessons from virtual outbreaks.

With that publication, the pair joined a growing cohort of behavioral scientists who are mining virtual worlds for real data on human behavior.

REAL LESSONS Computer programs that model how infectious diseases spread aren't new. Government and university researchers have been developing them for decades. But, say Fefferman and her colleagues, studying the actions of the millions of real people invested in World of Warcraft and other online worlds could substantially boost the reality quotient of disease simulators.

"The [computer] models we have are incredibly good at figuring out what the disease will do once we know what the behavior of the person is," Fefferman says. But the models make broad assumptions about how people will behave, and "we're pretty bad at knowing what those assumptions should be."

Lofgren, now an epidemiology graduate student at the University of North Carolina, Chapel Hill, says that "it is extremely hard mathematically to model risk aversion, or panic, or altruistic behavior, or noncompliance with quarantines." World of Warcraft players exhibited all of these behaviors during the outbreak.

In March, Ran Balicer, an epidemiologist at the Ben-Gurion University of the Negev in Be'er-Sheva, Israel, published a paper in Epidemiology outlining two particularly striking parallels between Hakkar's curse and real epidemics. First, virtual teleporting is like air travel, spreading bugs across the world in a flash. Severe acute respiratory syndrome (SARS), for instance, originated in China, but quickly dispersed as infected patients traveled in airplanes. Second, animals often act as reservoirs of human disease. With avian influenza, some fowl, especially ducks, "catch the disease in a mild way and then they transmit it onward, much like the animals in the game did," Balicer says.