HIERARCHICAL COMPLEXITY OF TASKS SHOWS THE EXISTENCE OF DEVELOPMENTALSTAGES

The major purpose of this paper is to introduce the notion of the orde r of hierarchical complexity of tasks. Order of hierarchical complexit y is a way of conceptualizing information in terms of the power requir ed to complete a task or solve a problem. It is orthogonal to the noti on of information coded as bits in traditional information theory. Bec ause every task (whether experimental or everyday) that individuals en gage in has an order of hierarchical complexity associated with it, th is notion of hierarchical complexity has broad implications both withi n developmental psychology and beyond it in such fields as information science. Within developmental psychology, traditional stage theory ha s been criticized for not showing that stages exist as anything more t han ad hoc descriptions of sequential changes in human behavior (Kohlb erg & Armon, 1984; Gibbs, 1977, 1979; Broughton, 1984). To address thi s issue, Commons and Richards (1984a,b) argued that a successful devel opmental theory should address two conceptually different issues: (1) the hierarchical complexity of the task to be solved and (2) the psych ology, sociology, and anthropology of such task performance and how th at performance develops. The notion of the hierarchical complexity of tasks, introduced here, formalizes the key notions implicit in most st age theories, presenting them as axioms and theorems. The hierarchical complexity of tasks has itself been grounded in mathematical models ( Coombs, Dawes, & Tversky, 1970) and information science (Lindsay & Nor man, 1977). The resultant definition of stage is that it is the highes t order of hierarchical complexity on which there is successful task p erformance. In addition to providing an analytic solution to the issue of what are developmental stages, the theory of hierarchical complexi ty presented here allows for the possibility within science of scaling the complexity in a form more akin to intelligence, (C) 1998 Academic Press.