Training Users: "Yes" and "No"

 If there are three things that must be nailed in your software's use model, these are it:
-Consistency
-Consistency
-Consistency
 
 If your use model is dead on, it will feel intuitive to users. They will know how to accomplish a task with little or no intervention from you.
 If your model isn't dead on, you wind up training your users to do things. They have to read your dialogs and make a decision, then act. As time goes on, they stop reading the dialogs. They don't have to think about it anymore.
 
 Take, for example, a file-tree-browsing tool that always displays a right-facing triangle to indicate a selection can be expanded. You can reuse that graphic elsewhere and users automatically know what it does. "I click here, I see more stuff under that selection." You want to avoid reusing the graphics in different contexts if there is different meaning.

 The same goes for dialog boxes.

  I recently loaded the "del.icio.us bookmarks" add-on for Firefox. Most of the yes/no dialogs in this OS in that web browser have the "yes" selection on the left. This tool's "no" selection is on the left. I wanted to add my bookmark to del.icio.us, but I quickly clicked the left box without reading the full dialog. Their software didn't do what I wanted, but that's what I've been trained to do.
 In the grand scheme of things that's no big deal. I can quickly recover from my "mistake" by manually uploading that bookmark to del.icio.us.

 Such was not the case the other day, however, when using my Palm Treo's calendar. I've edited my calendar any number of times. I've been trained to know that "yes" edits only one item in a set of recurring items. "No" edits the entire series of items. If I want to shift my schedule around for one day, I hit "yes." Easy enough.

 

  As you can clearly see, it's important to click "Yes" if you want to edit just one thing.

  My Friday class was canceled. I wanted to delete that one recurring item from my calendar for this week only. Easy enough, right? Click "delete", then click "Yes" to just delete one thing. But, wait...

   Well, you guessed it...I deleted the entire series. I clicked "yes" as I had been trained to do by the "edit" dialog. Deletion is an action so akin to editing that the buttons should behave similarly. Ah, well...maybe in the next version!

  When designing your interfaces and software behaviors, take care that affirmative and negative choices, or choices that result in similar behaviors, are always represented in the same way. Doing otherwise is a disservice to your users.