Developmental change and the multidimensional cognitive system

The cognitive system is a multidimensional, hierarchically-structured arrangement of cognitive dimensions functionally organized into three subsystems: perceiving, conceptualizing, and symbolizing. Ontogenetic change in these subsystems is described using theoretical concepts from both multivariate developmental psychology and systems theory. Both quantitative and qualitative changes in cognitive dimensions are discussed, including a synthesis of relevant empirical research. The Gompertz equation is used to describe the general form of quantitative change throughout the life-span. The pattern oo quantitative development involves growth, stability, and decline. The pattern of qualitative development, or shifts in structural organization, also invloves three periods: divergence, parallelism, and paraller-convergence. Thus, the overall quantitative-qualitative synthesis reveals a three-phase sequence of cognitive development: divergent growth (childhood- adolescence), parallel stability (adulthood), and parallel-convergent decline (old age).