Hierarchical Complexity of Tasks Shows the Existence of Developmental Stages

The major purpose of this paper is to introduce the notion of the order of hierarchical complexity of tasks. Order of hierarchical complexity is a way of conceptualizing information in terms of the power required to complete a task or solve a problem. It is orthogonal to the notion of information coded as bits in traditional information theory. Because every task (whether experimental or everyday) that individuals engage in has an order of hierarchical complexity associated with it, this notion of hierarchical complexity has broad implications both within developmental psychology and beyond it in such fields as information science. Within developmental psychology, traditional stage theory has been criticized for not showing that stages exist as anything more thanad hocdescriptions of sequential changes in human behavior (Kohlberg & Armon, 1984; Gibbs, 1977, 1979; Broughton, 1984). To address this issue, Commons and Richards (1984a,b) argued that a successful developmental theory should address two conceptually different issues: (1) the hierarchical complexity of the task to be solved and (2) the psychology, sociology, and anthropology of such task performance and how that performance develops. The notion of the hierarchical complexity of tasks, introduced here, formalizes the key notions implicit in most stage 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 & Norman, 1977). The resultant definition of stage is that it is the highest order of hierarchical complexity on which there is successful task performance. In addition to providing an analytic solution to the issue of what are developmental stages, the theory of hierarchical complexity presented here allows for the possibility within science of scaling the complexity in a form more akin to intelligence.