The oral stage in psychology is the term used by Sigmund Freud to describe the development during the first eighteen months of life, in which an infant's pleasure centers are in the mouth. This is the first of Freud's psychosexual stages.
If a child was not fed enough or was fed too much (over-protected), this may later create an oral fixation in that adult. It is believed that fixation in the oral stage can cause one of two things. If the child was treated well, fed lots, he will be orally dependent, and therefore selfish and wanton because he is used to getting what he wants. He might learn to manipulate others to fulfill his needs rather than maturing to independence. The overly indulged child may resist growing up and try to return to that state of dependency through crying, acting helpless, demanding satisfaction, and being "needy."
This is the infant's first relationship with its mother; it is a nutritive one. The length of this stage depends on the society. In some societies it is common for a child to be nursed by its mother for several years, whereas this stage is much shorter in other societies. Suckling and eating, however, compose the earliest memories for infants in every society. This stage, especially in some tribal societies, holds special importance because they consider the stomach to be the seat of emotions. These societies are commonly found in the Southwest Pacific and Africa.
Powdermaker, Hortense. "An Anthropological Approach to the Problems of Obesity".