Study: trolls are sadistic psychopaths

Lori Dorn of Laughing Squid says: "According to a new study conducted by the University of Manitoba Psychology Department, Internet trolls generally manifest signs of sadism, psychopathy, narcissism, and Machiavellianism, a group of personality disorders known as the Dark Tetrad."

Maggie posted about this last week, but here is a link to the research paper:
Trolls just want to have fun (PDF)