What makes people publicly shame others on social media?

The list of sources is 1.Social Media Impacts Behavior Norms (PDF attached) by Roberta Liggett & Stephanie Ueberall 2.The Psychology of Stranger Shaming by Aaron Balick http://www.aaronbalick.com/blog/the-psychology-of-stranger-shaming/ 3.The online disinhibition effect by John Suler https://www.academia.edu/3658367/The_online_disinhibition_effect

Topic is also closely related to a story with Justine Sacco. It is called ”How One Stupid Tweet Blew Up Justine Sacco’s Life” By JON RONSON (attached) I would like it to be mentioned as an example wherever it fits the best, perhaps in the introduction.