INVESTIGATING THE GRANULARITY OF THE UNDO FUNCTION IN HUMAN-COMPUTER INTERFACES

This paper presents three experiments on the granularity of the undo f unction in user-computer interfaces. The first two identify and analys e user expectations about the grain of undo in a word processing task and in a graphics task. The third one is more specific and tests how u sers expect different categories of actions to be undone in a graphics task. The results show that there are major individual differences in undo strategies, that action categories must be taken into account wh en defining undo granularity, and that users expect almost all kinds o f actions to be undoable.