This book presents new research on cognitive science which is most simply defined as the scientific study either of mind or of intelligence. It is an interdisciplinary study drawing from relevant fields including psychology, philosophy, neuroscience, linguistics, anthropology, computer science, biology, and physics. There are several approaches to the study of cognitive science. These approaches may be classified broadly as symbolic, connectionist, and dynamic systems. Symbolic holds that cognition can be explained using operations on symbols, by means of explicit computational theories and models of mental (but not brain) processes analogous to the workings of a digital computer. Connectionist (subsymbolic) holds that cognition can only be modelled and explained by using artificial neural networks on the level of physical brain properties.Hybrid systems hold that cognition is best modelled using both connectionist and symbolic models, and possibly other computational techniques. ''Dynamic Systems'' hold that cognition can be explained by means of a continuous dynamical system in which all the elements are interrelated, like the Watt Governor. The essential questions of cognitive science seem to be: what is intelligence? and how is it possible to model it computationally?