Principles of mixed-initiative user interfaces

Recent debate has centered on the relative promise of focusing user-interface research on developing new metaphors and tools that enhance users ’ abilities to directly manipulate objects versus directing effort toward developing interface agents that provide automation. In this paper, we review principles that show promise for allowing engineers to enhance human-computer interaction through an elegant coupling of automated services with direct manipulation. Key ideas will be highlighted in terms of the Lookout system for scheduling and meeting management.