Final answer:
Erikson's theory of psychosocial development and Kohlberg's theory of moral development are two major developmental theories that relate to psychological and sociological aspects of self-development.
Step-by-step explanation:
Erik Erikson's theory of psychosocial development is a major developmental theory that relates to both psychological and sociological aspects of self-development. According to Erikson, individuals go through eight stages of psychosocial development throughout their lives. Each stage involves a specific task or crisis that must be resolved in order to successfully progress to the next stage. For example, during the stage of adolescence, the major task is to establish a sense of identity, which involves exploring different roles and values.
Lawrence Kohlberg's theory of moral development is another relevant theory that combines psychological and sociological perspectives. Kohlberg proposed six stages of moral development, which involve the progression from a focus on external consequences to an internalized set of principles. For instance, in the preconventional stage, individuals make moral decisions based on avoiding punishment or seeking rewards, while in the postconventional stage, they develop their own ethical principles and act according to their conscience.