In Freudian psychoanalytic theory, defense mechanisms (or defense mechanisms) are psychological strategies brought into play by the unconscious mind to manipulate, deny, or distort reality (through processes including, but not limited to, Repression, Identification, or Rationalization), and to maintain a socially acceptable self-image or self-schema. Healthy persons normally use different defences throughout life. An ego defense mechanism becomes pathological only when its persistent use leads to maladaptive behavior such that the physical and/or mental health of the individual is adversely affected. The purpose of ego defence mechanisms is to protect the mind/self/ego from anxiety and/or social sanctions and/or to provide a refuge from a situation with which one cannot currently cope.
Defence mechanisms are more accurately referred to as ego defence mechanisms, and can thus be categorized as occurring when the id impulses are in conflict with each other, when the id impulses conflict with super-ego values and beliefs, and when an external threat is posed to the ego.
The term "defence mechanism" is often thought[who?] to refer to a definitive singular term for personality traits which arise due to loss or traumatic experiences, but more accurately refers to several types of reactions which were identified during and after Sigmund Freud's daughter Anna's time.