Erik Erikson (1902 - 1994) was a developmental psychologist and psychoanalyst, best known for formulating the Psychosocial Stages of Development which outlined personality development from birth to old age. He also coined the term Identity Crisis which describes when a person loses their sense of self.
However, Erikson is most remembered for the stages of development, so let's explore those in more detail. Each of the eight stages is marked by a conflict which must be successfully resolved in order to attain a favorable outcome, which he called "virtues."
The first stage of development (from birth to 18 months) is Trust vs. Mistrust. At this stage, the child learns to trust that the world is a safe place and that he can rely on his caregivers to provide for his needs, or to mistrust the world because his needs are not met. Successful resolution brings about the virtue of Hope.
The second stage (18 months to 3 years) is Autonomy vs. Shame. As the child learns to walk and begins to explore his environment, he learns autonomy as he develops more control over his bodily functions and his surroundings, or shame and doubt over his ability. If successfully resolved, the child develops the virtue of Will.
The third stage (3 to 5 years) is Initiative vs. Guilt. He learns initiative as he begins to do things for himself, or guilt over making his own choices. Successful resolution brings about the virtue of Purpose.
The fourth stage (6 to 12 years) is the conflict of Industry vs. Inferiority. As the child goes to school, he begins to compare himself with others and develops a sense of industry as he accomplishes new things, or a feeling of inferiority if he considers himself inadequate as compared to others. If successfully resolved, the child learns the virtue of Competence.
The fifth stage (12 to 18 years) corresponds to adolescence, when the child struggles between Identity vs. Role Confusion. The adolescent tries to develop his own sense of identity, but may experience role confusion as he tries to reconcile his own desires with that of others around him. Successful resolution enables the virtue of Fidelity.
The sixth stage (18 to 35 years) corresponds to young adulthood. The significant conflict that must be dealt with during this period is Intimacy vs. Isolation as the individual attempts to settle down and start a family. If successfully resolved, he learns Love.
The seventh stage (35 to 55 or 65) is that of the conflict between Generativity vs. Stagnation. This corresponds to the midlife crisis, when the adult assess his contributions to society, or becomes self-absorbed and stagnates. Successful resolution brings about the virtue of Care.
The last stage (65 onwards) is the conflict of Integrity vs. Despair, corresponding to late adulthood, when individuals look back at their accomplishments in life. If successfully resolved, the individual gains Wisdom.
Erikson's theory has contributed significantly to teaching and child-rearing practices, while providing psychotherapists with a roadmap as to what could be the significant conflict that needs to be resolved by the patient.