DEVELOPMENTAL TRANSITIONS - SO WHATS NEW

Structural approaches to development, such as Piaget's stage theory, h ave proved to be problematic in dealing with developmental transitions . More promising in this respect are models of qualitative change that address macroscopical phase shifts in non-linear dynamical systems th at arise from quantitative changes at the microscopical level. In this introductory paper, we attempt to clarify the meanings of some of the core terms used in these models so as to set the scene for the subseq uent contributions. We stress the relevance of recent advances in cata strophe theory for detecting developmental transitions and suggest tha t the concept of self-organization as formulated in irreversible therm odynamics provides a framework for explaining them. As yet, there is a lack of convincing evidence that transitions of interest to developme ntal psychologists comply with principles of self-organization that ha ve become well established for time-evolving systems in other discipli nes such as chemistry and biology. Demonstrations of self-organization in psychologically relevant simulation models are a first step in att aining such evidence. In this special issue, we concentrate primarily on a common approach to the detection of transitions across a number o f domains of development. However, in doing so illustrations are given of the ways in which the hypothesis of self-organization can be used to account for the mechanisms of developmental transitions.