Interpretation and visualization of user history in a spatial hypertext system

We describe a new history mechanism based on experiences with the use of recorded interaction history in the Visual Knowledge Builder (VKB). Problems with the use of history in prior systems include difficulty in locating activity of interest in large tasks, the problem of history records being at a system activity level rather than a human activity level, and difficulty in supporting navigation and comprehension in the branching histories used to represent alternative directions. To support comprehension of the history, we describe automatic history clustering to group low-level system events into a more human-level representation of activity and the extraction of information for summarizing these groups of events. To further support navigation and comprehension of history, the mechanism includes multiple visualization techniques to match diverse uses of history. The new history mechanism is integrated into VKB 3.