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Navigate on the right?
The jury is still out.

(SIGCHI Bulletin May/Jun 2002)

In a recent HFI newsletter, Bob Bailey presented a case for moving web site navigation to the right-hand side of the page. The evidence he cited was a study by Kellener, Barnes and Lingard on the effects of scroll bar orientation plus his own unpublished research on behalf of the National Cancer Institute.

The KB & L paper examined the relationship between item justification and vertical scroll bar placement within list boxes. They found both user performance and preference data supported scroll bar orientation consistent with item justification. That is, for left-justified items, users performed better and preferred a scroll bar on the left side. Similar results were found for right-justified items and scroll bars on the right side of the list box. However, these results are not very surprising given the very limited nature of the tests. They really act just as a confirmation of Fitt’s Law: that the time to acquire a target is a function of its distance and size. Users simply had to move the mouse from the scroll bar at the right or left side to the nearest point of the item to be selected.

Now maybe I am being a little fussy, but I personally would not be happy to extrapolate the KB & L results to web sites. It’s not that I don’t trust Fitt’s Law, but I am not certain that users spend most of their time moving between the scroll bar and the navigation fields with a mouse. Scroll bars are extremely fiddly widgets to operate on a regular basis and I for one use them only as a last resort, preferring the keyboard for most of my vertical scrolling operations. This is an effect that was overlooked in the KB & L study, since participants were instructed to use the mouse. It may be that Bailey’s own study was a little more open minded in this respect, but as the results are not publicly available, it is hard to say.

Before we start moving navigation controls to the opposite side from their expected location, let’s consider a few points:

  • Users may be scrolling with the keyboard.
  • Users may be scrolling with mouse wheels.
  • Users may not be moving between scroll bars and navigation fields as often as expected.
  • The window origin is usually in the top left, meaning that right edge varies in location according to width (although the relative distance to a right scroll bar would be fixed).

There is also Fitt’s Law to consider. We can improve task performance not only by moving the target closer, but by also making it larger. In fact size has the advantage over distance if we are not sure which targets users are moving between.

So my own view is that we need more data before we can know whether right navigation is going to be a real improvement. To collect this data, we should allow users to work as normal and set them realistic tasks, with navigation being varied in both location and size.

In the meantime, give users the largest navigation targets you can without making them scroll too much.

The Author

William Hudson is principal consultant for Syntagm Ltd, based near Oxford in the UK. His experience ranges from firmware to desktop applications, but he started by writing interactive software in the early 1970's. For the past ten years his focus has been user interface design, object-oriented design and HCI.

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© 2001-2005 ACM. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in SIGCHI Bulletin, {Volume 34, May-June 2002} http://doi.acm.org/10.1145/506320.506327

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