WASHINGTON (AP) — Those people who won't stop tweeting or posting their political viewpoints online may sometimes be annoying -- but a new survey suggests that they are in the minority.

In a report released today, the Pew Research Center finds that most people who regularly use social media sites are actually less likely than others to share their opinions, even offline.

The survey asked adults about the case of leaker Edward Snowden -- and it found that people who are on Facebook and Twitter were more likely to clam up on whether widespread government surveillance is a good thing.

The study, which was done in conjunction with Rutgers University in New Jersey, challenges the view of social media as a vehicle for debate. It suggests that sites like Facebook and Twitter might actually encourage self-censorship.

The researchers call it the "spiral of silence" phenomenon. They say unless people know that their audience agrees, they are likely to shy away from discussing anything controversial.

In other words, most of us are more comfortable with ice-bucket challenges than political banter.