Internet Trolls Are Narcissists, Psychopaths, and Sadists

In this month's issue of Personality and Individual Differences, a study was published that confirms what we all suspected: internet trolls are horrible people. 
Let's start by getting our definitions straight. An internet troll is someone who comes into a discussion and posts comments designed to upset or disrupt the conversation. Often, it seems like there is no real purpose behind their comments except to upset everyone else involved. Trolls will lie, exaggerate, and offend to get a response. 
What kind of person would do this?
Canadian researchers decided to find out. They conducted two internet studies with over 1,200 people. They gave personality tests to each subject along with a survey about their internet commenting behavior. They were looking for evidence that linked trolling with the Dark Tetrad of personality: narcissism, Machiavellianism, psychopathy, and sadistic personality.


[Edit to add: these are technical terms with formalized surveys to measure them. You can find lots more information about their formal definitions online]
They found that Dark Tetrad scores were highest among people who said trolling was their favorite internet activity. To get an idea of how much more prevalent these traits were among internet trolls, check out this figure from the paper:

 Look at how low the scores are for everyone except the internet trolls! Their scores for all four terrible personality traits soar on the chart. The relationship between this Dark Tetrad and trolling is so significant, that the authors write the following in their paper:
"... the associations between sadism and GAIT (Global Assessment of Internet Trolling) scores were so strong that it might be said that online trolls are prototypical everyday sadists." [emphasis added]
Trolls truly enjoy making you feel bad. To quote the authors once more (because this is a truly quotable article):
"Both trolls and sadists feel sadistic glee at the distress of others. Sadists just want to have fun ... and the Internet is their playground!"
So next time you encounter a troll online, remember a few things. (1) These trolls are some truly messed up people and (2) it is your suffering that brings them pleasure, so the best thing you can do is ignore them.