Harry Stack Sullivan was an American psychiatrist in the 1930s and 1940s. His work incorporated much of Sigmund Freud's research and beliefs. Sullivan believed that a child's experiences determine his adult personality. He also held the belief that a person's personality continues to develop into late adolescence and adulthood. Much of his theory focused on the stages of adolescence instead of early childhood. Sullivan lists six stages of development: Infancy, Childhood, Juvenile, Preadolescence, Early Adolescence and Late Adolescence.
Birth to Age 8
Sullivan's stages of development did not focus primarily on the early years. He believed that, in infancy (birth to age 1), the child learns to depend on caregivers to meet his needs. As the child moves into the Childhood stage (ages 1 to 5), he begins to develop speech and communication skills. He also learns to delay immediate gratification of needs and desires. The Juvenile stage (ages 6 to 8) focuses on social relationships. During this period, the child needs playmates and healthy socialisation.
Ages 9 to 12
Sullivan referred to the years from ages 9 to 12 as the Preadolescence stage. In these important, but brief, years, the child is learning to form close relationships with his peers. Sullivan believed the ability to have successful same-sex relationships in these years will later help the child feel worthy and likable. Without these successful relationships, the child will have difficulty later establishing intimate relationships during late adolescence and adulthood.
Ages 13 to 17
After Preadolescence, the child moves into Early Adolescence. During these years, the child is learning to be independent. He is also forming relationships with friends of the opposite sex. When puberty begins, this need for friendship will change into a need for sexual expression. The child's self-worth will often come from his sexual attractiveness and acceptance by friends of the opposite sex. There is some discrepancy on where Early Adolescence ends, but it is commonly between the ages of 15 and 17.
Ages 18 to 22
Sullivan describes the years from ages 18 to 22 as Late Adolescence. If the Early Adolescence stage ends before age 17, then Late Adolescence will begin sooner than 18 years. It is during these years that the need for friendship and sexual expression combine. The young adult is looking for a long-term relationship. Parental control versus self-expression is a source of conflict at this point.