ABSTRACT
This chapter outlines the information-processing analysis of text-editing. It describes the behavior of the user of a computer text-editing system by a cognitive theory composed of a small number of goals, operators, methods, and selection rules. The chapter explores models composed of these elements that give a reasonable quantitative account of the behaviour. It focuses on repeating the analyses with different goals, operators, methods, and selection rules for the methods (GOMS) models. For error-free behavior, a GOMS model provides a complete dynamic description of behavior, measured at the level of goals, methods, and operators. The use of the stack-discipline GOMS model should be taken as an approximation especially appropriate for skilled cognitive behavior and preferred here because of its greater simplicity. The general technique is to observe a user in a close laboratory analogue of the task he commonly performs, to describe his behavior using a GOMS model, and to evaluate in various ways the adequacy of the description.
