Moreover, Facebook friends can react more directly to vitriolic posts, either by calling the poster out or simply unfriending him or her, she says. In May, the site strengthened policies to stamp out hate speech.
"With Facebook, there's more accountability," says Vigil. "Most people's Facebook accounts have multiple pictures of them, they've got connections to 'these are my friends.' There's a lot less of the anonymity, so there's a little less of the disinhibition that occurs."
Twitter also creates more distance, adds Lesley Withers, a communications professor at Central Michigan University.
"It's asynchronous -- you're not chatting real-time with another person -- so there's less of a sense that the other people out there are real," she says. A phone call or even some kinds of online dialogue establishes a connection that you're dealing with actual human beings.
But on Twitter, that connection isn't there, so "that allows us to go off in ways that we wouldn't choose to do if we had to look at another person's face when we did it."
Twitter's brief screeds seldom have consequences, though that may be changing. The site recently created a "report abuse" button and the media -- which is often to blame for highlighting anger -- is paying more attention to bullying on the site.
But the idea of consequences is hard for Twitter users to understand, observes Withers.
"I think people don't think about the long-term ramifications," she says. "When I talk with students about how they use social media and say that a lot of employers will look to see what kinds of things you're posting on Facebook or Twitter, I'm surprised by the number of people who say, 'Any employer that would stalk me that way online, I wouldn't want to work for them anyway.'"
There are signs that a growing number of Twitter users don't like the venom in their midst. After the nastiness with Miss America, a number of people responded with positive tweets congratulating her. Some even reprimanded the angry tweeters -- and received apologies.
"I am so sorry. I didn't think before I tweeted what I did. I absolutely did not mean to hurt or offend anyone. Again I am SO very sorry!!!" tweeted @JAyres15.
Withers points out that the system has much to overcome.
"People use Twitter to get reactions out of others," she says. "It's like a popularity contest: If you can put something out there that's quick and inflammatory and it gets retweeted a ton, that's your feedback -- that's how you know that it was an interesting or effective tweet. And people don't seem to be as concerned if the response is positive or negative."
And what works? Let's all scream it at the top of our lungs: Anger.
"Anger is an empowering emotion. You can post something angry and it can make other people feel something. It allows us an opportunity to be dramatic," says Withers. "And a lot of people really like drama."