The Life-Span Perspective in
Paul B. Baltes
Hayne W. Reese
Max Planck Institute for Human Development Education
West Virginia University
We define the goals of developmental psychology as the description, explanation, and modification of intraindividual change in behavior across the life span, as well as the interindividual differences in such change (Baltes, Reese, & Nesselroade, 1977). The basic assumption is that life-long changes in the behavior of individuals are not random and that many of these changes can be understood in terms of principles of development. This definition also emphasizes that the life-span development of different individuals is similar in some respects and different in others. Thus, we need to understand not only how individuals develop alike, but also how differences in life-span development come about, and how and why individuality occurs in development.
This chapter presents a life-span perspective on psychological development. A life-span perspective is one based on the belief that the changes (growth, development, aging) shown by people from the time of their conception, throughout their lives, and until the time of their death are usefully conceptualized as developmental. Life-span developmental psychologists take one or both of the following two approaches to their subject matter: They focus on a category of behavior (e.g., memory, intelligence, or personality) and study it in terms of the life-long processes of constancy and change, or, they work on the holistic delineation of age periods (e.g., infancy, childhood, adolescence, adulthood, or old age), and the interconnections among these periods. These two approaches,