“Defense Mechanisms” are certain ways in which we think or behave that serve to protect or “defend” our egos/identities from emotional pain or suffering. People often use defense mechanisms to distance themselves from gaining a full awareness of their own unpleasant thoughts, feelings, and behaviors.

The more primitive a defense mechanism, the less effective it works for a person over the long-term. However, more primitive defense mechanisms are usually very effective short-term, and hence are favored by many people and children especially (when such primitive defense mechanisms are first learned). Adults who don’t learn better ways of coping with stress or traumatic events in their lives will often resort to such primitive defense mechanisms as well.

Most defense mechanisms are fairly unconscious – that means most of us don’t realize we’re using them in the moment. Some types of psychotherapy can help a person become aware of what defense mechanisms they are using, how effective they are, and how to use less primitive and more effective mechanisms in the future.

Vaillant's categorization of the 4 levels of defense mechanisms:

Level 1 - Pathological
Defense mechanisms on this level, when predominating, almost always are severely pathological. These four defenses, in conjunction, permit one to effectively rearrange external experiences to eliminate the need to cope with reality. The pathological users of these mechanisms frequently appear irrational or insane to others. These are the "psychotic" defenses, common in overt psychosis. However, they are found in dreams and throughout childhood as well.
They include:

• Delusional Projection: Grossly frank delusions about external reality, usually of a persecutory nature.
• Denial: Refusal to accept external reality because it is too threatening; arguing against an anxiety-provoking stimulus by stating it doesn't exist; resolution of emotional conflict and reduction of anxiety by refusing to perceive or consciously acknowledge the more unpleasant aspects of external reality.
• Distortion: A gross reshaping of external reality to meet internal needs.
• Splitting: A primitive defense. Negative and positive impulses are split off and unintegrated. Fundamental example: An individual views other people as either innately good or innately evil, rather than a whole continuous being.
• Extreme projection: The blatant denial of a moral or psychological deficiency, which is perceived as a deficiency in another individual or group.

Level 2 - Immature
These mechanisms are often present in adults and more commonly present in adolescents. These mechanisms lessen distress and anxiety provoked by threatening people or by uncomfortable reality. People who excessively use such defenses are seen as socially undesirable in that they are immature, difficult to deal with and seriously out of touch with reality. These are the so-called "immature" defenses and overuse almost always leads to serious problems in a person's ability to cope effectively. These defenses are often seen in severe depression and personality disorders. In adolescence, the occurrence of all of these defenses is normal.
They include:

• Acting out: Direct expression of an unconscious wish or impulse in action, without conscious awareness of the emotion that drives that expressive behavior.
• Fantasy: Tendency to retreat into fantasy in order to resolve inner and outer conflicts.
• Idealization: Unconsciously choosing to perceive another individual as having more positive qualities than he or she may actually have.
• Passive aggression: Aggression towards others expressed indirectly or passively such as using procrastination.
• Projection: Projection is a primitive form of paranoia. Projection also reduces anxiety by allowing the expression of the undesirable impulses or desires without becoming consciously aware of them; attributing one's own unacknowledged unacceptable/unwanted thoughts and emotions to another; includes severe prejudice, severe jealousy, hypervigilance to external danger, and "injustice collecting". It is shifting one's unacceptable thoughts, feelings and impulses within oneself onto someone else, such that those same thoughts, feelings, beliefs and motivations are perceived as being possessed by the other.
• Projective identification: The object of projection invokes in that person precisely the thoughts, feelings or behaviors projected.
• Somatization: The transformation of negative feelings towards others into negative feelings toward self, pain, illness, and anxiety.

Level 3 - Neurotic
These mechanisms are considered neurotic, but fairly common in adults. Such defenses have short-term advantages in coping, but can often cause long-term problems in relationships, work and in enjoying life when used as one's primary style of coping with the world.
They include:

• Displacement: Defense mechanism that shifts sexual or aggressive impulses to a more acceptable or less threatening target; redirecting emotion to a safer outlet; separation of emotion from its real object and redirection of the intense emotion toward someone or something that is less offensive or threatening in order to avoid dealing directly with what is frightening or threatening. For example, a mother may yell at her child because she is angry with her husband.
• Dissociation: Temporary drastic modification of one's personal identity or character to avoid emotional distress; separation or postponement of a feeling that normally would accompany a situation or thought.
• Hypochondriasis: An excessive preoccupation or worry about having a serious illness.
• Intellectualization: A form of isolation; concentrating on the intellectual components of a situation so as to distance oneself from the associated anxiety-provoking emotions; separation of emotion from ideas; thinking about wishes in formal, affectively bland terms and not acting on them; avoiding unacceptable emotions by focusing on the intellectual aspects (e.g. isolation, rationalization, ritual, undoing, compensation, magical thinking).
• Isolation: Separation of feelings from ideas and events, for example, describing a murder with graphic details with no emotional response.
• Rationalization (making excuses): Where a person convinces him or herself that no wrong was done and that all is or was all right through faulty and false reasoning. An indicator of this defense mechanism can be seen socially as the formulation of convenient excuses - making excuses.
• Reaction formation: Converting unconscious wishes or impulses that are perceived to be dangerous into their opposites; behavior that is completely the opposite of what one really wants or feels; taking the opposite belief because the true belief causes anxiety. This defense can work effectively for coping in the short term, but will eventually break down.
• Regression: Temporary reversion of the ego to an earlier stage of development rather than handling unacceptable impulses in a more adult way.
• Repression: The process of attempting to repel desires towards pleasurable instincts, caused by a threat of suffering if the desire is satisfied; the desire is moved to the unconscious in the attempt to prevent it from entering consciousness; seemingly unexplainable naivety, memory lapse or lack of awareness of one's own situation and condition; the emotion is conscious, but the idea behind it is absent.
• Undoing: A person tries to 'undo' an unhealthy, destructive or otherwise threatening thought by engaging in contrary behavior.

Level 4 - Mature
These are commonly found among emotionally healthy adults and are considered mature, even though many have their origins in an immature stage of development. They have been adapted through the years in order to optimize success in life and relationships. The use of these defenses enhances pleasure and feelings of control. These defenses help us integrate conflicting emotions and thoughts, while still remaining effective. Those who use these mechanisms are usually considered virtuous.
They include:

• Altruism: Constructive service to others that brings pleasure and personal satisfaction.
• Anticipation: Realistic planning for future discomfort.
• Humor: Overt expression of ideas and feelings (especially those that are unpleasant to focus on or too terrible to talk about) that gives pleasure to others. The thoughts retain a portion of their innate distress, but they are "skirted round" by witticism.
• Identification: The unconscious modeling of one's self upon another person's character and behavior.
• Introjection: Identifying with some idea or object so deeply that it becomes a part of that person.
• Sublimation: Transformation of negative emotions or instincts into positive actions, behavior, or emotion.
• Thought suppression: The conscious process of pushing thoughts into the preconscious; the conscious decision to delay paying attention to an emotion or need in order to cope with the present reality; making it possible to later access uncomfortable or distressing emotions while accepting them.