ABSTRACT
Th e usability of systems is determined by interface functionality and presentation. Much research in human factors has concentrated primarily on presentation-the surface aspects of the interface. Today, interface presentation and interaction have greatly improved to the extent that navigating the interface is much easier. Understanding complex system functionality from a presentation is diffi cult, and functionality alone has a dominant impact on usability. Th is problem is termed the human factors of functionality. It complements the study of mental models-how users adapt to and understand system functionality (Kieras, 1990; Rouse, Salas, & Cannon-Bowers, 1992). Th is chapter describes a user-centered architecture that adapts to users rather than requiring users to adapt to it. Its structure and conceptual organization diff er radically from traditional automation.
