Freud’s Defense Mechanisms

Freud defined defense mechanism as a technique that the ego uses to protect itself from anxiety and threats which give rise to anxiety. Anxiety is a negative emotional state which arises due to conflict between the id and superego.

Repression: one blocks threatening thoughts and memories which are then repressed down into the unconscious. Freudians view depression as a result of excessive repression.
Identification: when one incorporates characteristics of a drive object into one’s own ego.
Displacement: when one displaces redirects drive energy from one object to a substitute object.
Rationalization: one makes an excuse for behavior and thoughts which are either threatening or unacceptable.
Projection: one tries to protect themselves from threat by projecting their own traits to other people.

Exaggerated use of defense mechanisms results in Neuroses (anxiety driven patterns of abnormal behavior from over control of instincts)

Sources:
Glassman, William E., and Marilyn Hadad. Approaches to Psychology. 4th ed. New York: Open Univesity Press, 2004.
Dalal, Neeraj. "Personality Theories: Chapter 2." IB Psychology. Mac. 7 Apr 2008 >.

mage:

http://www.bu.edu/mih/images/Freud.jpg