Develop System Menus and Navigation Schemes 349

Step 4: Develop System Menus and Navigation Schemes 349

link may transport the user to another location within a page, to a new site page, or to another Web site. Originally, due to the nature of technology at the time hypertext was employed in computer systems, links only consisted of textual or binary files. Utilization of hypertext on the Web allowed links to be created using images as well as text, so the term hypermedia was coined to reflect this expanded nature.

In addition to being the critical component in Web navigation, links give the user an idea of what a Web site, document, or page is all about. The wording of a textual link should enable a person to predict what lies submerged below, or what will happen if it is activated. Descriptive links let the user determine whether a link should be followed or not. This is a complex cost-benefit calculation that the user makes many times in a Web interaction session.

Providing an extensive collection of link navigation tools will focus the user on the Web site itself and its content, drawing attention away from the general-purpose browser links. Making these tools consistent and predictable will help the user create an understandable mental model of the site and its organization. To begin, several gen- eral link guidelines are

All navigation elements must —— Make sense in the absence of site context.

—— Be continually available. —— Be obvious and distinctive. —— Be consistent in appearance, function, and ordering. —— Possess a textual label or description. —— Offer multiple navigation paths.

Sensible. All navigation controls, in the absence of site context, must make sense to

the user. The user may have “lost” the context, or the page or Web site may have been entered from almost anywhere.

Available. All navigational controls must be easy to access. If they are not readily available, the full advantages of hypermedia may not be achieved.

Obvious and distinctive.

A navigation link or control must look like a navigation

control. Its appearance to the user must immediately suggest that it is an entity to

be clicked or otherwise selected. This is accomplished through a control’s appear- ance as well as its location. Non-obvious link or control choices lead to aimless and tedious page clicking and ultimately confusion and frustration. Conversely, do not make any other screen element look like a navigation tool if it is not one.

The obviousness of a link is called its affordance. A control with high affor- dance will be quickly identified as a control. Bailey (2000) in a study compared the link affordances of the homepages for two large Web sites. Each page con- tained 29 links. The link affordance rate for one site was 97 percent (participants, on the average, identified 28.2 page links). The rate for the other site was only 76 percent (the average link identification rate being 21.9 per page). This difference was statistically significant. Because of the non-obviousness of one-quarter of the poorer site’s links, its users would have spent longer times searching for links, and would probably not have even discovered some links. Techniques to create

350 Part 2: The User Interface Design Process

link. Guidelines enabling the various controls to achieve distinctiveness are described in the following control-specific sections.

Consistent. Like all elements of the interface, navigation links, toolbars, and com- mand buttons must be consistent in appearance and behavior. Textual. All navigation must have a textual label or description. Navigation using textual descriptions is much preferable to graphical-only navigation because the purpose and function of graphic images are often unclear. They also take longer to download. Textual links are also necessary for users who do not have graphics, or who have chosen not to display graphics.

Provide multiple navigation paths. Offer multiple paths or ways to move around the Web. Provide structural components such as site maps, a table of contents, and indexes to go directly to a point of interest, provide content links to move around nonsequentially, and provide command buttons, such as Next and Previous, to move sequentially.