Sigmund Freud proposed a systematic theory of human development that focused on unconscious conflicts and emotional issues that form personality. Adapting a metaphor of thermodynamics to show how unconsciousness processes dynamically interact to help people adapt to the environment and cope with conflict, Freud proposed that personality develops from a person's struggle to meet needs in a world that frustrates needs attainment.

Freud theorized that there are three distinct and interacting parts in the personality: the id, the superego, and the ego. Freud believed that humans are motivated by the basic drives, which are either adaptive or maladaptive based on how the id, ego, and superego develop and interact (Freud, 1923; M. W. Watson, 2002). Freud shocked the Victorian world by asserting the core element of development is achieving sexual maturity, and that all aspects of development connect to sexual development (Goldhaber, 2000). Freud proposed a psychosexual developmental sequence to show how the pleasure-seeking energy of the id centers on different erogenous zones during different stages of life, which included oral, anal, phallic, latent, and genital (Freud, 1920).

Perspectives on Freud

Wade and Tavris (2008) pointed out that many scholars consider Freud's ideas to be "nonsense", with little support from research. However, Freud's ideas still influence culture and the field of human development. Freud was one of the first to define the concept of developmental stages, which became a key feature of the organismic theories that followed (Goldhaber, 2000). Freud also introduced important concepts like the unconscious influence on behavior, the importance of previous events and relationships on the present, how defense mechanisms and conflicting desires influence mental processing and the existence of sexual desire as a motivator (M. W. Watson, 2002).

Neo-Freudian theorists attempted to align psychodynamic theory with empirical work. For example, Erik Erikson (1993) shifted from sex as a primary motivator to social and environmental influences on development and identified stages of adult development beyond adolescence. Erikson proposed eight stages through which humans experience psychological crisis as they develop from infancy to old age, including basic trust versus basic mistrust, autonomy versus shame, initiative versus guilt, industry versus inferiority, identity versus role confusion, intimacy versus isolation, generativity versus stagnation, and ego integrity versus despair (1993).

In short, though flawed, Freud introduced provocative ideas that encouraged tinkering from other theorists (Wade & Tavris, 2008), laying the foundation through which some organismic theorists would build, and others would raze.

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