A 2013 study, from Beihang University in Beijing, of Weibo, a Twitter-like site, found that anger is the emotion that spreads the most easily over social media. Joy came in a distant second. The main difference, said Ryan Martin, a psychology professor at the University of Wisconsin, Green Bay, who studies anger, is that although we tend to share the happiness only of people we are close to, we are willing to join in the rage of strangers. As the study suggests, outrage is lavishly rewarded on social media, whether through supportive comments, retweets or Facebook likes. People prone to Internet outrage are looking for validation, Professor Martin said. “They want to hear that others share it,” he said, “because they feel they’re vindicated and a little less lonely and isolated in their belief.”…

Yet outrage carries a different flavor from pure anger; it suggests an affront to one’s value system as opposed to seething, Hulk-like fury. So whereas a venomous insult from an anonymous commenter simply seeks to tear down another person or institution, an outraged Twitter post from an identified account calls attention to the user’s own probity. By throwing 140-character stones from our Google Glass houses, we preserve our belief (or delusion) that we are morally superior to those who have offended us.

The emotion plays well on social media because of its brevity and conviction, too. A 700-word Facebook post accounting for all sides of a contentious issue is unlikely to garner as many readers and endorsements as a one-sentence quip blaring heightened feelings.