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Right-Justified Navigation Menus Impede Scannability
Written by Jakob Nielsen   
Sunday, 27 April 2008

We know from eyetracking studies that users tend to rapidly move their eyes down the left-hand side of lists. People read the rest of a list item only if something catches their eyes in these left-most one or two words.

The menu design guidelines are thus clear, at least for vertical menus:

  • Left-justify the menu, so that the user's eyes can move in a straight line and don't have to re-acquire the beginning of each new line.
  • Start each menu item with the one or two most information-carrying words.
  • Avoid using the same few words to start list items, because doing so makes them harder to scan.
Aligning a navigation menu with the right margin might look cool, but the resulting ragged left margin severely reduces the speed with which users can scan the menu and select their preferred options.

(Of course, the left-alignment guideline is for languages that read left-to-right. For languages that read in the opposite direction, the guideline is reversed: you should right-justify the menu. In either case, the point is to make it easier for users to scan down the side on which they start reading.)

Take a look at the following screenshots. I picked university sites for this illustration, but right-aligned navigation disease is found on business sites as well.

Read the full article at http://www.useit.com/alertbox/navigation-menu-alignment.html