Some Maine voters are receiving mailers  that advocate not for a candidate, but for voting.

With over $10.4 million spent on political advertisements telling Mainers who to vote for, who not to vote for and who can’t win, one would think voters are so bludgeoned that some will decide to stay home. This is a bad outcome for political parties, particularly Maine Democrats, who have been pumping up their voter mobilization in an effort to match, or overtake, Republicans in the midterm election.

So after a bunch of mailers and television advertisements designed to evoke dread and anger, groups want to make sure that certain voters actually vote. And how are they doing it?

By using that old social desirability trick.

Check out the mailer above. It doesn’t endorse or oppose a specific candidate. It advocates for voting — “Be a voter,” it says. It does so by comparing the recipient’s voting participation to their neighbors. In this case, the voter is an active voter, but I’ve seen a few of these in which the recipient isn’t as active as their neighbors. The idea is to trigger some sense of guilt or an innate need to keep pace with your neighbors. Political campaigns have been using this method for some time. So have some utility companies, which in some states send ratepayers bills that compare their electricity usage to their neighbors, an effort designed to get consumers to conserve energy.

So how does America Votes, a D.C.-based group that partners with progressive organizations, know the above recipient’s voter history? Voter information is confidential. However, Maine and other states allow political organizations and those that conduct voter mobilization efforts to access the Central Voter Registration database. The database has detailed information about your party registration, where you live, whether you voted in a primary or general election and how often. In other words, these groups know if you’ve voted or even if you’ve already requested and returned an absentee ballot.