Psychological repression, or simply repression, is the psychological act of excluding desires and impulses (wishes, fantasies or feelings) from one's consciousness and attempting to hold or subdue them in the subconscious. Since the popularization of Sigmund Freud's work in psychoanalysis, repression is popularly known to be a common defense mechanism.
Repression is considered unconscious and can often be detrimental. It may be contrasted with suppression, which is entirely conscious and thus can be managed. Because repression is unconscious, it manifests itself through a symptom or series of symptoms, sometimes called the "return of the repressed." A repressed sexual desire, for example, might re-surface in the form of a nervous cough or a slip of the tongue. In this way, although the subject is not conscious of the desire and so cannot speak it out loud, the subject's body can still articulate the forbidden desire through the symptom.
A person can suppress the impulse to "choke the life out of some idiot who desperately needs it" for higher reasons, such as sociability, or more mundane reasons, like keeping a job - especially if it's a co-worker or boss being considered for the assault. The desire remains conscious, but is thwarted by the exercise of willpower due to a rational decision to avoid the action.
In spite of the popularity and wide use of this concept in psychoanalysis and popular literature, this proposition of "motivated forgetting," where the motivation is (1) unconscious and (2) aversive, the process of repression has never been demonstrated in controlled research. It is often claimed that traumatic events are "repressed," yet it appears that it is more likely, not less, that the occurrence of these events is remembered, if in a distorted manner. One problem from an objective research point of view is that a "memory" is usually defined as what someone says or does, that can measured and recorded, since we have no way to verify the existence and/or accuracy of a memory except by the correspondence of what someone clearly expresses with some other representation of past events (written records, photographs; reports of others, etc).
Normal repression is sometimes considered to have two stages, which are progressively involved in the creation of the individual's sense of "self" and "other", of "good" and "bad", and of the aspects of personality called "ego" and "superego".
In the Primary Repression phase, the infant learns that some aspects of reality are pleasant, and others are unpleasant, and that some are controllable, and others not. In order to define the "self", the infant must repress the natural assumption that all things are equal. Primary Repression then is the process of determining what is self, what is other, what is good and what is bad. Once done, the child can now distinguish between desires, fears, self, and mother/other.
Secondary Repression begins once the child realizes that acting on some desires may bring anxiety. For example, the child who desires the mother's breast may be denied and feel threatened with punishment, perhaps by the father. This anxiety leads to repression of the desire for the mother's breast. The threat of punishment related to this form of anxiety, when internalized becomes the "superego", which intercedes against the desires of the "ego" without the need for any identifiable external threat.
Abnormal repression, or complex neurotic behavior involving repression and the superego, occur when repression develops, or continues to develop due to the internalized feelings of anxiety, in ways leading to behavior that is illogical, self-destructive, or anti-social.
A psychotherapist may try to reduce this behavior by revealing and re-introducing the repressed aspects of the patient's mental process to his conscious awareness, and then teaching the patient how to reduce any anxieties felt in relation to these feelings and impulses.