You didn't know it at the time, but when you logged into Facebook on Election Day, you became a subject in a mass social experiment. You went about your day, clicked around Facebook, and you may have voted. Now your behavior is data that social scientists will scrutinize in the months ahead, asking one of the core questions of democracy: What makes people vote? If patterns from earlier research hold true, the experiment's designer James Fowler says that it is "absolutely plausible that Facebook drove a lot of the increase" in young-voter participation (thought to be up 1 percentage point from 2008 as a share of the electorate). It is, he continued, "even possible that Facebook is completely responsible."
Assuming you are over the age of 18 and were using a computer in the United States, you probably saw at the top of your Facebook page advising you that, surprise, it was Election Day. There was a link where you could find your polling place, a button that said either "I'm voting" or I'm a voter," and pictures of the faces of friends who had already declared they had voted, which also appeared in your News Feed. If you saw something like that, you were in good company: 96 percent of 18-and-older U.S. Facebook users got that treatment, assigned randomly, of course. Though it's not yet known how many people that is, in a similar experiment performed in 2010, the number was 60 million. Presumably it was even more on Tuesday, as Facebook has grown substantially in the past two years.
But here's the catch: Four percent of people didn't get the intervention. Two percent saw nothing -- no message, no button, no news stories. One percent saw the message but no stories of friends' voting behavior populated their feeds, and 1 percent saw only the social content but no message at the top. By splitting up the population into these experimental and control groups, researchers will be able to see if the messages had any effect on voting behavior when they begin matching the Facebook users to the voter rolls (whom a person votes for is private information, but whether they vote is public). If those who got the experimental treatment voted in greater numbers, as is expected, Fowler and his team will be able to have a pretty good sense of just how many votes in the 2012 election came directly as a result of Facebook.
They've done a very similar experiment before, and the results were significant. In a paper published earlier this year in Nature, Fowler and his colleagues announced that a Facebook message and behavior-sharing communication increased the probability that a person votes by slightly more than 2 percent. That may not seem like a huge effect, but when you have a huge population, as Facebook does, a small uptick in probability means substantial changes in voting behavior.
"Our results suggest," the team wrote, "that the Facebook social message increased turnout directly by about 60,000 voters and indirectly through social contagion by another 280,000 voters, for a total of 340,000 additional votes." This finding -- remarkable and novel as it may be -- is in concert with earlier research that has shown that voting is strongly influenced by social pressure, such as in this 2008 study which found that people were significantly more likely to vote if they received mailings promising to later report neighborhood-wide who had voted and who had stayed at home.
Although months of door knocking, phone calls, and other traditional campaign tactics surely bring more people to the polls, those measures are expensive and labor-intensive. Nothing seems to come even close a Facebook message's efficacy in increasing voter turnout. "When we were trying to get published," Fowler told me, "We had reviewers who said, 'These results are so small that they're meaningless,' and other reviewers who said, 'These results are implausibly large. There's no way this can be true.' " In a country where elections can turn on just a couple of hundred votes, it's not far-fetched to say that, down the road, Facebook's efforts to improve voter participation could swing an election, if they haven't already.
Now it must be said that of course Facebook is not trying to elect Democrats. Facebook has an admirable civic virtue and has long tried to increase democratic participation in a strictly nonpartisan way. "Facebook," Fowler said to me, "wants everyone to be more likely to vote. Facebook wants everyone to participate in the fact of democracy."