With the increasing use of interactive computer systems, it is becoming ever more important to provide friendly and efficient interfaces to the user. This book is intended to provide an introduction to design techniques for human/computer interaction, recognizing that the user interface is a vital aspect of the design of the whole system. It includes an overview of relevent theory and experimental evidence from cognitive psychology and the human sciences. The book is written from the engineer's point of view, concentrating in particular on the specification and analysis of interactive systems. There is detailed coverage of hardware and software techniques for dialogue design and case studies are used to illustrate practical implementation.