While the notion of human development can be traced back almost a century to the work of Arnold van Gennep, Jose Ortega y Gasser, and Carl Jung, it gained prominence and a stable theoretical base with the work of Swiss psychologist Jean Piaget (1896-1980) and German-born psychoanalyst Erik Erikson (1902-1994). Piaget (Inhelder and Piaget 1958) identified four specific sets of cognitive competencies that must be acquired in a sequential manner as children mature and become thoughtful and successful adults, and one must successfully achieve the cognitive com¬petencies associated with one stage of the Piagetian model before proceeding to the next stage.

A few years later, Erikson (1985) described eight stages of life, from infancy through old age. Unlike Piaget, Erikson assumed that one moves on to the next stage of development in life, regardless of one’s level of success in the previous stage or stages. In the Piagetian model, unsuccessful development results in a person’s being stuck at a specific stage of life. Conversely, in the Eriksonian model, one carries developmental failures forward in life, making success in each of the subsequent stages more difficult as the continuous accumulation of failures becomes more damaging and difficult to overcome.

Eriksonian Models of Adult Development

The first four of Erikson’s developmental stages address the issues of infancy and childhood. The last four stages address the issues of adulthood. The fifth stage concerns primarily the formation of identity as an adult, and the building of a sense of continuity in life roles and goals, while the sixth stage focuses on the capacity to establish an intimate relationship and the formation of a loving relationship with another person. Generativity is central to the seventh stage, with midlife adults concerned with guidance of the next generation. The eighth and final stage concerns primarily the integrity of one’s life experiences and the acceptance of one’s own distinctive life cycle (Erikson 1982).

Nature of the life cycle

The basic Eriksonian model has undergone two major extensions and modifications over the past three decades (Gilligan 1982; Levinson 1996; Levinson et al. 1978). Like Erikson, Levinson addresses the life cycle, but his studies of the life cycle in men (Levinson et al. 1978) and women (1996) focus on the last three Eriksonian stages, specifically on the seventh stage. Within the seventh stage, Levinson concentrates on the transitions associated with the early 40s, expanding on Erikson’s model by identifying both structure-building periods and structure-changing or transitional periods within specific life-cycle eras. The crises and stress associated with transitional periods are normal aspects of the developmental process and are to be differentiated from adaptive crises, which occur when a major traumatic event occurs in one’s life (such as combat, illness, or abuse).