Thursday, April 12, 2007

Usability and Mode Errors

Modal errors in application UIs ...

"What’s a mode error or a modal error? In usability speak, that’s when the user confuses the mode they’re currently in, causing a wrong or ineffective action. For example, when I click on a contact’s note on my Windows Mobile OS (which has a very low overall usability), and I open up the keyboard to enter a note with my stylus pen, I can’t – I’m in read-only mode (indicated by the lack of a blinking text cursor inside the note field). Only after I hit “edit” at the bottom will I switch to edit mode to be able to enter something. I committed a “mode error.”

Here are some more examples of mode errors:

• You hit “paste” but didn’t focus the input field, so nothing will be pasted.

• You hit Ctrl+Z on Windows (the “undo” short-cut) but the application doesn’t keep a history, and thus doesn’t support undo’s.

• You want to paint some pixels on a photo but you selected the “lasso” tool; the mode was indicated by a different cursor, but you didn’t notice.

• You sub-consciously “think” Ctrl+Z when you make an error writing with a pen on paper (hands up, who had this happen to them?).

As application developer, you know your interface needs optimization if users commit too many modal errors! For example, your mode indicator may be too subtle (e.g. the title bar of your application’s window turns from light gray to dark gray when it’s activated, a color change that’s easily missed). Or you’re introducing unnecessary modes: the “enter something into field 1” mode which uses different short-cuts from the “enter something into field 2” mode, even when field 1 and 2 seem to be related! (This is often a problem with Flash applications on the web, as they only emulate the OS modes up to a point, but don’t get things – like short-cuts or scroll behavior – completely right.)"    (Continued via WebProNews)    [Usability Resources]


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