ABSTRACT
Development is frequently described as progressing through a series of “levels of organization” or “stages of development.” The concept of levels of organizations has been used extensively in the preceding portions of this work. A level of organization is a qualitatively distinct form of organization in an ordered series of such forms. A stage of development, on the other hand, is one interval in a temporally ordered series of intervals during which either: (1) There is little internal change in a structure with regard to some particular function; or (2) one form of organization dominates the others with respect to some particular function, or both. The levels-by-stages model is thus primarily concerned with the relationship between the formal ordering of structures and their temporal order. This model provides the basis for the developmental theories of Freud, Piaget, Erikson, Sullivan, Kohlberg, Loevinger, and many others. It is also implicit in the concepts of precocity, retardation, and regression.
