Final answer:
Sigmund Freud continued to work on and promote his psychoanalytic theory in 1918, focusing on the unconscious mind's impact on behavior and the significance of early childhood experiences in shaping personality.
Step-by-step explanation:
In 1918, Sigmund Freud continued to develop his psychoanalytic theory, which became one of the most influential concepts in the history of psychology. Freud's work on psychoanalysis involved the 'talking cure' with patients, where he focused on the unconscious mind as a repository of suppressed feelings and urges. His theory suggested that accessing these unconscious elements was crucial for alleviating psychological distress and for understanding the root causes of certain symptoms such as hysteria and neurosis.
Freud's hypothesis that unconscious forces, primarily sexual in nature, were responsible for the neurotic symptoms observed in his patients was groundbreaking. The psychosexual development theory, controversial as it is, was a significant part of his work, claiming that early childhood experiences play a pivotal role in shaping an individual's personality. This theory and his methods, while debated and often criticized, laid the groundwork for modern clinical psychology and influenced subsequent researchers and theorists.