Mechanisms in the explanation of developmental change

Despite extensive use of the term mechanism in developmental psychology, and in theories of cognitive development in particular, scant attention has been given to specification of what the concept entails. The principal aim of this paper, by focusing on its implicit assumptions, has been to detail at least one view of how mechanism should be conceptualized. As with any general concept, the illustrations of its use in selected developmental theories point to differences in the ways aspects of the concept are treated. They suggest, too, why consensus in arriving at a unified concept of mechanism has been and will continue to be difficult. Nevertheless, the following conclusions can be drawn from the foregoing conceptual analysis and the analysis of selected applications. In the explanation of the operation of a mechanism, one must assume a temporal (asymmetrical) relation of either a single set or a series of initial conditions to an event, condition, or structure denoted as an effect. The relation of the antecedent to the consequent event(s) is describable by some theory of causal explanation. Implicit in any description of mechanism, then, is a theory of causal explanation. However, a strict account of causal relations, in which necessary and sufficient conditions of causal explanation are met, is not possible in any of the sciences. In addition, adequate reference to mechanisms requires the specification of structures, whether material or immaterial, and their constituent parts, with the parts related to each other in a systematic way. Such systems of structural components are operated upon by some process or set of processes that produces particular effects. Hence, mechanism and process are not interchangeable terms, nor does mechanism underlie process. Instead, in a mechanism, structure and process are complements of each other. Among the specific models of development mechanisms examined, all provide varying notions of process, but only some are directly concerned with the specification of structure. To the extent that they omit structures they are limited in their accounts of the mechanisms they are purported to describe and explain. Neuroscience accounts of developmental change most directly confront structure-function relations. In being closely allied to biological theories, they forthrightly acknowledge structural and functional forms of causal explanation. Dynamic system theories, in contrast, in emphasizing the dynamics of change, appear to place their primary, if not sole emphasis on the functional aspects of development. Nevertheless, implicit in their accounts are references to structure, often couched in the language of organization.(ABSTRACT TRUNCATED AT 400 WORDS)