Designed for Use, 2nd Edition

Sticky Modes

This is my alarm clock. To change the time the when the alarm goes off, I have to push the topmost button. This puts the clock into its “change alarm time” mode. In that mode, the topmost button now changes the hour of the alarm. So, if I can’t push this button again to exit the mode, how do I exit the mode?

It is often not obvious to the user how to resolve an active mode, and this causes usability problems. Another example of this is the Insert key on PC keyboards. Once the user has activated the overtype mode by hitting the Insert key (perhaps by accident), it is entirely unclear and nonobvious how to go back to the “normal” ...