On Structure and Process in Lifespan Cognitive Development

For the most part, researchers in cognitive development investigate the emergence of cognitive abilities from birth until about ten or twelve years old, and researchers in cognitive aging confine their inquiries to adults beyond the age of about sixty years. In both cases, although more so in cognitive aging, comparisons are also made with the performance of high-functioning young adults, usually university undergraduates, from whom deviations in performance are measured. The related notions of plasticity, adaptation, and compensation are central to understanding lifespan changes in cognitive processing. The pattern of development and decline of cognitive abilities depends on the observation perspective one takes and the size of the lens through which one peers. These differences are illustrated by describing the evidence from three perspectives that progressively narrow the lens and sharpen the focus: context and performance, differentiation-dedifferentiation, and representation and control. In each case, this chapter considers whether there is evidence for developmental growth and decline; and if so, whether the rise and fall are symmetrical and whether the patterns of change can be traced to the same underlying mechanisms.