Abstract

In cognitive psychology there appears to be a creative tension between models that use connections of a network, and models that use rules for symbol manipulation. The idea of a connectionist network goes back to McCulloch & Pitts [1943] and Hebb [1949], and finds recent revival in the `parallel distributed processing' (PDP) models that have been extensively examined in the last few years (see e.g. Rumelhart et al. [1986]). In the intervening years, however, the predominant explanations of psychology have been in terms of rules for the manipulation of symbolic structures (e.g. since Newell & Simon [1963]). Because of the tension between these different approaches (see e.g. Fodor & Pylyshyn [1988]), there is great interest in the formulation of `hybrid systems' which combine connectionist components with traditional symbolic processing. I attempt below to outline the general architecture of such a hybrid system.