It has been both a pleasure and an honor to edit this book. The pleasure has been in interacting with the gifted authors who wrote the chapters for this volume and the honor has been in knowing that the book is dedicated to a great man and a brilliant psychologist-Daniel E. Berlyne. All the contributors to this book have been touched, at some time, by Dan Berlyne and his ideas. Whether as his teachers, his colleages, his peers, his students, or his friends and arguing partners, we have all felt his presence and been improved by it. The list of contributors to this volume is large and could have been much larger, for a number of people, in fact, contacted me for the oppor tunity to contribute when they heard about the purpose of this book. It is also an international list, for Dan Berlyne's contacts were international. The diversity in content and style is also intentional. The authors were invited to contribute an original paper in the field in which they are presently engaged, whether theoretical or a report of empirical work, and to indicate the contribution that Dan Berlyne had made to their work. As the reader will note, contributions range from personal and contact in a laboratory to ideas that elicit controversy, argument, and intensive re search. Daniel Ellis Berlyne was born in Selford, England, a suburb of Man chester,in 1924, and died in Toronto, Canada, on November 2, 1976.