Final answer:
Erik Erikson added to psychology by proposing the psychosocial theory of development, which includes eight stages extending from birth to death and emphasizes social influences on personality development over the entire lifespan.
Step-by-step explanation:
Erik Erikson significantly contributed to the field of psychology by expanding on Sigmund Freud's theories and proposing a comprehensive theory of personality development that extends across the human lifespan. Erikson's theory, known as the psychosocial theory of development, includes eight stages of development, from birth to death. Unlike Freud, who emphasized psychosexual stages and the influence of biological drives, Erikson highlighted the influence of social relationships and experiences, suggesting that personality is shaped by the ongoing interplay between individual needs and societal expectations, and that it continues to evolve throughout a person's life.