The aim of this book is to bring together and try to inter­ relate some of the concepts and relevant knowledge from the varfous disciplines concerned with this area of research and application, including especially the human sciences, computer sciences and engineering. The focus throughout is up0n the human rather than upon the computer issues in Man-Computer Interaction (MCI). The book is based upon the papers presented by invited speakers at an Advanced Study Institute held at Mati, Attica, Greece 5-18 September 1976, which was sponsored by the NATO Advanced Study Institutes Programme. These papers were not intended to be ency­ clopaedic or to yield a 'state of the art' volume. But as revised here they do represent well the scope and breadth of MCI ('man' is used throughout generically for men, women, humans, people). The material in this book is as timely today as when presen­ ted in lectures; it is not out of date. Indeed in many respects it is more timely, because the computer industry is now recognising the need to heed the users. Computer designers are becoming receptive to the importance of the human factors aspects. Recognition of the user's needs has been stimulated by the work, elsewhere as well as here, of the contributors to this book.