When Undo is No Help at All
I remember when Photoshop only had one level of undo. You had to take great care with every action, or you would be starting over. Today, nearly infinite levels of undo and redo are standard fare. Why would anyone complain about having an undo feature.
There’s a particularly poorly designed piece of software used for media presentation in worship services called MediaShout. The UI defies all logic, and I could cite any number of perfect examples of how not to design an application. My wife ran into one today. After importing and formatting over sixty slides, she hit the wrong undo button. What’s that, you say? There are multiple undo buttons? Indeed. She meant to hit the one that undid the last edit she made on the current slide. Instead, she hit one that is for actions taken at a higher level of the application’s cognitive model. In this case, it undid the action in which she had added the container into which she had imported the slides. When she pressed the redo button, it recreated the container, but all of the imported slides and the formatting she had done to them were lost. She had to start over.
The application’s cognitive model doesn’t match the user’s. The user doesn’t perceive two distinct levels of activity with separate sequences of events that should be controlled by separate, yet identical buttons. Ironically, the undo button creates the exact situation it is intended to avoid.
