Facebook just revealed some interesting figures about who responded to its reminder to vote this recent presidential election day. Combined with evidence that a similar widget sent an extra 340,000 voters to the polls in 2010, the new figures suggest that Facebook’s decision to implement the feature directly boosted president Obama’s vote tally.

The reminder offered up a button labeled “I’m a voter”, and showed the names and faces of friends that had already clicked it. In a new blog post, Facebook data scientist Eytan Bakshy, tells us about the people most likely to have clicked that button on November 6, and it seems clear that more of them would have voted for Barack Obama than Mitt Romney.

Although many more will have seen the “I’m a voter” button, nine million people clicked it. Twice as many women as men did so, while exit polls tell us that overall Obama led with female voters. Meanwhile, almost 20 percent of people who stated their political affiliation as “Barack Obama”, “Democratic” or “Very liberal” clicked Facebook’s “I’m a voter” button, while only about 15 percent of those identifying as “Republican” or “Independent” did so.

Many of those people would have voted anyway. However, we know that the “I voted” reminder that shows a person which of their friends also clicked can turn out votes that would otherwise not be cast.

Research published in the prestigious journal Science in September told us that in 2010 a version of the voting reminder similar to that used this month drove an additional 340,000 voters to polls nationwide. James Fowler, a political scientist at the University of California, San Diego, led the study, which involved matching public voter records with Facebook’s data (see “How Facebook Drove Voters to the Polls”).

So, if the same effect was at work this time around, Facebook’s get out the vote reminder would clearly have boosted the number of votes cast for Obama. That’s something my colleague David Talbot suggested could happen in advance of the election (see “Facebook’s Plans Could Affect the Election”).