As this book took form, its contents furnished the material for a graduate course at the University of Rhode Island. Toward the end of that course, the class reviewed the literature on display characteristics and design. The universal criticism voiced in those reviews was that there was lots of hardware information but no criteria upon which one could base a sound design. Though one could learn all about the size and brightness of various displays, one could not form any judgment about how ef­ fectively the display transferred information to an observer. As I reviewed our nearly completed text, an announcement crossed my desk stating that one of the professional societies in a seminar was to consider if one should not attempt to formulate a theory concerning information transfer from displays to an observer. That was the first title chosen for our book, before our publisher told us that "that was a paragraph, not a title. " The group of contributors to this book have labored long in the conviction that there was a real need to develop and present a consolidated theory based upon the work of a number of pioneers, including Barnes and Czerny, de Vries, Rose, Coltman and Anderson, Schade, Johnson, van Meeteren, and others, who established the various parts of a substantial theoretical and experimental back­ ground that seemed ripe for consolidation.