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When Links Change: How Additions and Deletions of Single Navigation Links Affect User Performance

Lauren F.V. Scharff and Philip Kortum

Journal of Usability Studies, Volume 5, Issue 1, Nov 2009, pp. 8 - 20

Article Contents


Discussion

Web sites must occasionally make navigation changes, and it is important to understand the impact of such changes on the user.

The data presented here show that, even after a single prior visit to a site, users’ performance in searching for target information can be hindered by the loss of a single important link. Somewhat surprisingly, this performance decrement is evident even after an extended period of time after the user first used the site. This means that Web designers need to take extra caution when altering the navigation structures for pages, even when the users of those pages might be defined as occasional users. Our study indicates that users maintain some knowledge of site and link structure for at least three weeks, even if the users only visited the site a single time before. Web designers need to insure that the links that are removed are those that traffic statistics support as being no longer important.

In reviewing the site diagrams, it is clear that when users are looking for their lost link, they do so by navigating progressively wider using the remaining navigation links, rather than performing a narrower search closer to the page where they believed the link to be. They also tend to be less able to find the information on the second visit, giving up before they can reacquire the information. This has implications for providing alternate pathways to critical information and insuring that these alternate pathways remain if the top level link must be deleted.

Happily, the converse is also true; the addition of a single link can enhance performance if the link is germane to the task at hand, even if the user had established a navigation path to the target information on a previous visit. This means that if an analysis of site traffic indicates that a page needs to have a top-level navigation link, there is a good chance that even previous users (about half) will find, see, and use the added link. Even users who don’t find the added link will still exhibit improvements in their performance, reinforcing the fact that secondary paths to information should not be deleted simply because a top-level navigation link has been added.

There are several potential limitations of the study that may have impacted the results. First, the study used college students as participants, and these students were in general quite Web literate. It is possible that users with less Web experience might have different performance on this kind of information searching task. Second, the design of the study itself might have had an impact on users’ performance. Because the information search task was an isolated task completed in a single session, the task might have been more memorable than if the task had been performed as part of a series of Web tasks. Certainly in the no delay task, the lack of intervening stimuli would allow maximum access to the participants’ previous memories of the page. It is likely that the delay task was less affected by this design, because the participants would have likely had significant Web use in the intervening interval.

 

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