Which defense mechanism involves faking a belief opposite to the true belief?

The correct choice identifies reaction formation as the defense mechanism that involves adopting beliefs or behaviors that are opposite to one's true feelings or beliefs. This psychological strategy often serves to protect an individual from anxiety stemming from unacceptable thoughts or feelings. For instance, a person who harbors feelings of hostility toward someone may instead display exaggerated kindness and friendliness toward that person.

This mechanism is significant because it enables individuals to cope with their internal conflicts and emotional disturbances without consciously acknowledging them. By exhibiting behaviors or sentiments that are contrary to their true beliefs, individuals can avoid facing the discomfort associated with those emotions. Reaction formation can be observed frequently in social interactions, where individuals may act in ways that seem contradictory to their inner feelings, reflecting a complex inner psychological landscape.

The other choices represent different defense mechanisms, which do not fit the description provided in the question. Understanding reaction formation can help those studying psychology to identify and interpret behaviors in both themselves and others accurately.