Facebook knows how to trick you into voting

President Obama speaks at a town hall meeting at Facebook headquarters.

President Obama speaks at a town hall meeting at Facebook headquarters. Pablo Martinez Monsivais/AP

Peer-pressure on the social network drove 340,000 people to the polls in 2010, a new study has found.

Contagion is a funny thing. Carly Rae Jepsen is catching (248 million YouTube views and counting), as are West Nile virus (1,993 cases as of last week) and iPhone 5 hysteria (larger screen! Built-in soft-serve dispenser!). Obamania proved infectious in 2008, but the 2012 strain is markedly less intense. Romneymania, for its part, has yet to sweep the land.

As it turns out, civic participation also exhibits viral qualities: In an article that appears this week inNature, political scientists at the University of California, San Diego, demonstrate that a single Facebook message during the 2010 midterm elections drove some 340,000 voters to the polls -- simply because their friends had voted, too.

James Fowler and his colleagues partnered with the social-media site to develop what he describes as perhaps the largest randomized, controlled trial ever performed: on Election Day, 2010, nearly every American user over the age of 18 who logged onto Facebook -- some 60 million people -- saw a message at the top of their News Feed encouraging them to go vote. A link was provided to their polling location, as were an "I Voted" button and prominent photos of six friends who'd already done so. But the researchers had worked out two control groups with Facebook, each 600,000 people large. One control group saw no civic message at all. The second was encouraged to vote, but without any of the social pressure markers -- no photos of friends, no reminder that "Jaime Settle, Jason Jones, and 18 others" had done their democratic duty.

When the researchers later compared state voter rolls with Facebook users who'd been targeted (a subset of all voters, 217 million of whom were eligible to vote that year), they found that civic participation was infectious among friends. Not only was Sara on Facebook more likely to go vote if she'd received social pressure through the site to do so, but Sara's friends and friends of Sara's friends were more likely to go vote, too. The subtle encouragement, or guilt, rippled across two degrees of Facebook separation.

Read more at The Atlantic.