Adult development encompasses the changes that occur in biological and psychological domains of human life from the end of adolescence until the end of one's life. These changes may be gradual or rapid and can reflect positive, negative, or no change from previous levels of functioning. Changes occur at the cellular level and are partially explained by biological theories of adult development. If an adult is 'stuck' in a predominantly kinesthetic, auditory or visual mode of representation, this is a case of arrested development - he is at the concrete operational level of development, or maybe lower. At the primary school level, the education of children is .
Erick Erickson’s (, ) theory of psychosocial development, in which he argues that development is primarily a result of social interactions, has three stages that occur during adult development (intimacy vs. isolation, generativity vs. stagnation, and integrity vs. despair). Adult development theory, the longer version In our society, we freely talk about the maturation and mental development of young people, from infants to toddlers to young children to pre-teens to young adults. We all see and accept that their brains grow and evolve.
In fact, research suggests that adult cognitive development is a complex, ever-changing process that may be even more active than cognitive development in infancy and early childhood (Fischer, Yan, & Stewart, ). Becoming an ‘adult’ means transitioning to higher stages of development. It means developing an independent sense of self and gaining the traits associated with wisdom and social maturity.