According to Sigmund Freud, a defense mechanism in which frightening or socially unacceptable emotions are transformed into their opposite behaviors.
Example: A young man who fears he might be gay joins a conservative church and becomes very involved with anti-homosexuality activism.
Grinnell, R. (2008). Reaction Formation. Psych Central. Retrieved on July 31, 2015, from http://psychcentral.com/encyclopedia/2008/reaction-formation/