Abstract
Differentiation-dedifferentiation as a theoretical construct in lifespan developmental research
has most often been used to describe increasingly similar versus dissimilar between-person
differences in the changes of multiple intellectual abilities. Based on data from the Interdis-
ciplinary Longitudinal Study of Adult Development (ILSE) we argue that differentiation-
dedifferentiation may be used as a general guiding principle in developmental research. We
demonstrate how the principle can be extended towards generally describing multiple traits
between persons that include intellectual abilities and personality, towards describing within-
person longitudinal development, and towards describing micro- and macrodevelopmental
changes within- and between-persons aligning goal-related activities in a way that supports
leading individually meaningful lifes.
Zimprich, D