ABSTRACT
This chapter addresses the issues of applying psychology to system design. It proceeds by enumerating the principal aspects of the application framework—the human-computer system, performance models, and design functions—and by showing how far we have progressed and where needs exist for future research. The chapter describes Roberts's methodology for evaluating text editors, her empirical results, and how these extend the results so far reported. It focuses on two performance variables—functionality and learning. Performance can only be assessed relative to the set of tasks that must be done. The central feature of the applied psychology is the packaging of psychological knowledge into performance models that can predict the performance of the human-computer system from specifications of its structure. The models have been validated in a variety of human-computer systems, which has also produced a useful database of empirical performance data.
