Why Consistency is Critical

"There is often a tendency to do clever things with user interface elements -- frequently, with the best intentions -- that cause problems. For example, some sites execute an action when a user selects an option button (or radio button). This behavior can be very confusing if it is unexpected. Saving a single click at the expense of consistent behavior is probably not a good strategy.

The most basic requirement for consistency in UI elements is to apply them as they are originally defined. For example:

- Option buttons (radio buttons) only for mutually-exclusive items, so that the user can choose only one option
- Check boxes if the user can choose one or more options
- Avoid applying unnecessary graphical treatment that can confuse the user, making them user of the type of UI element they are using. Option buttons should be round, check - - boxes square. Editable fields should have white backgrounds; non-editable fields should be grey.

As an example, consider the Google 'advanced search' page, which contains text fields, push-buttons, drop-downs, option buttons, links and various other elements, all of which are clearly discernible for what they are."