MELISSA BLOCK, HOST:
Every election season Republicans and Democrats tried to rally their base and to go after undecided voters. They're increasingly using the Internet in Get Out The Vote efforts.
NPR correspondent Shankar Vedantam, who reports on social science research, joins me now to talk about how Facebook could become a potent weapon in going after the biggest untapped voting bloc in the nation. Shankar, welcome.
SHANKAR VEDANTAM, BYLINE: Hi, Melissa.
BLOCK: Who are these mystery voters, this untapped voting bloc that we mentioned?
VEDANTAM: Well, I have long thought, Melissa, that the Americans who do not vote are the single most important political story in our country. So if they were to form their own party, not only would they be larger than the Democrats and larger than the Republicans, they would nearly be larger than the Republicans and the Democrats put together.
And if you go back and look at midterm elections, going back more than half a century, turnout is always been under 50 percent. In presidential elections, it hovers around 50 percent.
BLOCK: So is the puzzle how to get 50 percent actually to go to the polls? Is that what they're trying to figure out?
VEDANTAM: That is exactly right. But in many ways, if you flip the question on its head, the mystery actually is not so much why so many people don't vote, but why so many people do vote. I mean, just think about this. So you have half the country voting, but of those votes only about a fifth of the votes really count because they're the people who live in this swing states. You live in California or Texas or New York or Maryland, like I do, the truth is no one is really campaigning there because the outcome is pretty clear.
And political scientists have done a lot of experiments looking at how you can get nonvoters to vote. And I spoke with a political scientist whose name is James Fowler. He is at the University of California, San Diego. And he tells me that the experiments all points in one direction.
JAMES FOWLER: The most powerful engine for getting people to participate in politics is the social network.
VEDANTAM: In other words, if you want to get people to vote, you don't reach them through television advertisements. You reach them through their friends.
BLOCK: The social network, so this is where Facebook comes in; a way of doing exactly that - reaching you through your friends.
VEDANTAM: Exactly, so what Fowler did on Election Day in 2010 is he ran this massive experiment, where people logged into Facebook saw a button on top of their newsfeeds. And the button said: I Voted. And also, a subset of those people saw photographs of six of their friends who had clicked the I Voted button.
And what Fowler found was that people who saw photographs of their friends who had clicked the I Voted button, were significantly more likely themselves to click the button saying that they had voted.
BLOCK: When people click things on Facebook and all the time.
BLOCK: It doesn't mean they actually did, right? They might have clicked I Voted and who knows whether they did.
VEDANTAM: Well, that's true. So what Fowler also did was he ran the information that people gave to Facebook by state voting records. And he was able to track down the six million people whose information they provided to Facebook - first name, last name and date of birth - match their state voting records.
And looking only at the subset of people, he was a able to conclude that substantially more people who saw photographs of their friends who had voted, actually showed up to vote on Election Day, compared to people who hadn't seen those people photographs.
FOWLER: What we have shown here is that the online world and the real world affect one another. And in this case, we find that this message that started online, that spread online actually affected real world behavior. It got a third of a million people to the polls.
VEDANTAM: You know, Melissa, I've read the study. It was published in the journal Nature. And I'd have to say that Fowler is actually being very conservative about his results, because he's looking only at the six million people whom he could verify as voters. The actual message went out to 60 million people, so it's very likely that the actual effect, in terms of getting nonvoters to vote, was significantly larger than a third of a million.
BLOCK: And if I read the study right, Shankar, it's a small number percentage-wise. But multiplied over many millions of people, it adds up.
VEDANTAM: That's exactly right. And that's the power of Facebook, of course, because tens of millions of people are on Facebook everyday.
BLOCK: This was an experiment that was conducted during the 2010 congressional elections. What about now? Are the campaigns using this technique that we're talking about?
VEDANTAM: I mean, you have to imagine that they're doing so. So every time you get a message on Facebook from the Obama or Romney campaigns, or every time you get a tweet from them, saying please like this message or please retweet this, what they're doing is taking advantage of the fact that when you amplify a message from the campaign, it's much more effective than the campaign sending out messages directly.
I mean, it's gotten to the point that, you know, a lot of people think that Obama and Romney are spamming them.
BLOCK: Shankar, thanks so much.
VEDANTAM: Thanks, Melissa.
BLOCK: That's NPR's Shankar Vedantam, who covers interesting social science research. You can follow him on Twitter @hiddenbrain. And while you're at it, you can follow this program @npratc. Transcript provided by NPR, Copyright National Public Radio.