How to do Undo

Michael Jason Smith, PhD Student

Dept of CSSE, University of Canterbury

Fri Dec 17 15:10:00 NZDT 2004 in Room 031, MSCS

Abstract

Undo is a common feature of many text-editors, word-processors, drawing programs and the like. It allows errors to be easily corrected and thereby encourages system exploration. However, despite the prevalence of Undo there has been no study which implementation of Undo is the best.

I present the results of a study I conducted into four error- recovery methods, including Undo, to determine which allowed the user to recover from errors in a text-editor and drawing program in the shortest time. I found that Undo did not allow participants to correct simple errors in the shortest time when using a text-editor, but similar errors in the drawing program were corrected in the shortest time using Undo. For more complex errors, a tree-based error-recovery method, similar to that provided by versioning systems, allowed participants to recover from errors in the shortest time in both the text-editor and drawing program.