5.01 Ego Defenses Psychiatry review for the USMLE Step 1 Exam Defense mechanisms protect the unconscious part of our personality from anxiety caused by unacceptable thoughts or feelings. Ego defenses are categorized into three groups: mature, neurotic, and immature. Immature defense mechanisms include projection, regression, denial, acting out, and splitting. Projection involves attributing objectionable thoughts or emotions to others. Regression is behaving in an age-inappropriate way to avoid tension associated with the current phase of development. Denial is not accepting or believing something to protect one's ego. Acting out involves giving in to socially inappropriate impulses to avoid anxiety. Splitting is viewing people as either all good or all bad, without considering the middle ground. Neurotic defense mechanisms include intellectualization, isolation of affect, displacement, rationalization, reaction formation, and repression. Intellectualization is overanalyzing situations or focusing on irrelevant details to avoid negative feelings. Isolation of affect is unconsciously limiting the experience of emotions associated with a stressful event. Displacement involves shifting emotions from one thing to another, which is deemed more acceptable. Rationalization is justifying one's behavior or negative feelings through rational explanations. Reaction formation is unconsciously acting opposite to an unacceptable impulse. Repression involves preventing thoughts or feelings from entering consciousness to avoid negative emotions. Mature defense mechanisms include humor, altruism, suppression, and sublimation. Humor is used to relieve anxiety and negative thoughts. Altruism involves performing beneficial acts for others to experience pleasure and relieve anxiety. Suppression is consciously blocking undesirable ideas, thoughts, or impulses. Sublimation is transforming anxiety or emotions into socially valued pursuits. Sublimation involves channeling negative emotions into productive and socially desirable actions.