Why are we so nasty to each other online, asks Elizabeth Bernstein in the Wall Street Journal. Whether on Facebook, Twitter, message boards or websites, we say things to each other that we would never say face to face. Shouldn’t we know better by now?

Anonymity is a powerful force. Hiding behind a fake screen name makes us feel invincible, as well as invisible. Never mind that, on many websites, we’re not as anonymous as we think—and we’re not anonymous at all on Facebook. Even when we reveal our real identities, we still misbehave.

According to soon-to-be-published research from professors at Columbia University and the University of Pittsburgh, browsing Facebook lowers our self control. The effect is most pronounced with people whose Facebook networks were made up of close friends, the researchers say.