James E. Marcia
James E. Marcia is a clinical and developmental psychologist. Marcia is best known for his research and writings on adolescent psychosocial development and lifespan identity development. His theory of identity achievement posits that there are two distinct parts in the achievement of adolescent identity: a time of choosing or crisis and a commitment (a decision of which choice to pursue). Crisis was defined as a time of upheaval where old values or choices are being reexamined and new alternatives are being explored.