A type of defense mechanism whereby unacceptable, anxiety-causing emotions or impulses are masked by an exaggerated version of the opposite emotions or impulses.
This mechanism can be very confusing for a loved one because the person in question may treat their child/spouse horribly (get in fights with them all the time, yell) to try and hide the fact that they deeply love them. Since the emotions (either hate or love) cause worry or intimidation some peoples’ minds choose not to address them at all.
Example: A professor who goes out of her way to be friendly with a certain colleague actually harbors an intense dislike for her fellow academic.
Fournier, G. (2010). Reaction Formation. Psych Central. Retrieved on August 2, 2015, from http://psychcentral.com/encyclopedia/2009/reaction-formation-2/