Exploration of Developmental Variables by Manipulation and Simulation of Age Differences in Behavior

It is argued that developmental research should be oriented towards the explication of age changes by the manipulation of variables hypothesized to be associated with age. A number of strategies are discussed which permit short-term manipulation (simulation) of ontogenic change (age functions) in laboratory or controlled settings. These strategies are explored regarding their power in isolating the major variables whose effects are age (or time)-related and in providing information about the key developmental antecedents of age differences as they exist in natura. Although it was argued that such simulation strategies can supply suggestive evidence on key developmental variables, a number of caveats are added, primarily regarding the question of isomorphy between simulated and biotic developmental change. The consideration of these strategies, however, also focuses attention on the inherently descriptive nature of research designs which involve the use of age as an independent variable, further clarifies the role of chronological age in developmental theories, and highlights the potential importance of variables whose effects are manifested over time (or are age-related) but are not directly apparent when conventional cross-sectional or longitudinal methods of data collection are used.