Those GOTV Facebook messages campaigns want you to send to your friends? They actually help increase turnout, according to a new study in the journal Nature.

A randomized, controlled study of approximately 61 million Facebook users found political mobilization messages, posted during the 2010 U.S. Congressional races, encouraged voting, information-seeking and self-expression. Those effects extended to friends and friends-of-friends, among those who received the messages.

The informational message contained a link to the nearest polling place, while the social message also included photos of the user’s friends who already reported voting. Users could indicate they voted by pressing the “I Voted” button in the center of the message. A tally of reported voters was kept at the top, right corner of the message.    

Overall, the messages resulted in 340,000 additional voters, according to the research.  

“The effect of social transmission on real-world voting was greater than the direct effect of the messages themselves, and nearly all the transmission occurred between ‘close friends’ who were more likely to have a face-to-face relationship,” reported Nature. “These results suggest that strong ties are instrumental for spreading both online and real-world behavior in human social networks.”  

Of the Facebook users tested, 98 percent received social messages on their News Feeds and half of the remainder informational messages. The control group was kept to a mere 600,000 users because Facebook wanted all users participating in the election.