HOW USERS REPEAT THEIR ACTIONS ON COMPUTERS: PRINCIPLES FOR DESIGN OF HISTORY MECHANISMS

Abstract

Several striking characteristics of how often people repeat their actions on interactive systems are abstracted from usage data gleaned from many users of different classes over a period of months. Reformulated as empirically-based general principles, these provide design guidelines for history mechanisms specifically and modern user interfaces generally. Particular attention is paid to the repetition of command lines, and to the probability distribution of the next line given a sequential "history list" of previous ones. Several ways are examined of conditioning this distribution to enhance predictive power. A brief case study of actual use of a widely-used history system is also included.