Erik Erikson is a theorist who believed that every stage of life has an associated developmental task to accomplish for optimal development to occur. According to Erikson, the task of adolescence is identity formation vs. identity diffusion.
Identity formation involves forming who you will be going forward based on positive reinforcement during adolescence—who one is, where one is headed in life, and what one believes in. People who achieve identity formation clearly understand their personal needs, values, and life goals.
Erikson believed identity formation is the key developmental task of adolescence and sets the stage for meeting the next life challenge: achieving intimate, secure relationships with others. In other words, we need to know who we are before we can reveal our true selves to others in the context of close, binding relationships.
Some adolescents may fail to develop a clear sense of identity formation, creating identity diffusion. This is when negative reinforcement causes an individual to not have a firm grasp of self in relation to the world. They remain in a state of role diffusion, a confused and drifting state in which they lack direction in life.