Final answer:
James Marcia's research supports Erikson's theory on identity development, focusing on the social aspects of personality development throughout an individual's lifespan and expanding on the stage of identity versus role confusion.
Step-by-step explanation:
The research that supports Erikson's theory on identity development is most closely associated with James Marcia. James Marcia expanded upon Erikson's understanding of identity development within the psychosocial developmental stages. Marcia's work specifically examines Erikson's stage of identity versus role confusion and adds different identity statuses to assess the process of identity development in adolescents and young adults.
Erikson's theory holds that personality development takes place throughout the lifespan and emphasizes the social nature of our development, contrasting Sigmund Freud's view that personality is shaped only in childhood. Erikson proposed that at each stage of development, there is a psychosocial task that we must master to feel a sense of competence. James Marcia's research built on this theory, staying true to the social focus but adding empirical evaluation to the process of identity formation.