Freud believed that the primary areas of instinctual gratification, the erogenous zones, moved across childhood in predictable stages. His theory of the psychosexual stages included the oral, anal, phallic, and genital stages. Each psychosexual stage had specific psychological characteristics to it. For example, the anal stage was characterized by stinginess, concern with money, and/or wish for control. If the child was either undergratified or overgratified in any stage, the child could fixate at that stage, becoming, in effect, psychologically stuck.

Neurotic symptoms would reflect the person’s characteristic psychosexual stage. For example, obsessions and compulsions reflected regression to the anal stage. While Freud’s instinctual theory has been much criticized, the notion that developmental problems at any point in childhood can hinder later development and result in adult psychopathology must be seen as one of Freud’s greatest contributions.