Psychoanalytic theory posits that an individual unable to integrate difficult feelings mobilizes specific defenses to overcome these feelings, which the individual perceives to be unbearable. The defense that effects (brings about) this process is called splitting. Splitting is the tendency to view events or people as either all bad or all good. When viewing people as all good, the individual is said to be using the defense mechanism idealization: a mental mechanism in which the person attributes exaggeratedly positive qualities to the self or others. When viewing people as all bad, the individual employs devaluation: attributing exaggeratedly negative qualities to the self or others.

In child development, idealization and devaluation are quite normal. During the childhood development stage, individuals become capable of perceiving others as complex structures, containing both good and bad components. If the development stage is interrupted (by early childhood trauma, for example), these defense mechanisms may persist into adulthood.