21. User-centered design of hypertext/hpermedia for education

Cliff McKnight

Loughborough University of Technology

Andrew Dillon

Indiana University

John Richardson

Loughborough University of Technology

21.1 What is hypertext; what is hypermedia?

The prefix hyper usually means "more than," so we may begin by asking what is it that hypertext has that makes it more than text (see 24.6.1). The simple answer to tbis is that as well as text, hypertext has "links." The text is usually organized into chunks, units, or "nodes," as they have come to be known, and the links form connections between certain nodes.

There are no "rules" about how big a node should be or what it should contain. Similarly there are no rules governing what gets linked to what. Hence, there can be many different kinds of hypertext in the same way that there are many different kinds of text. Furthermore, hypertext allows the concept of "document" to be extended since, logically, entire documents can be treated as nodes and linked together to form a single hypertext.

The concept of links between units of information has a history almost as old as writing itself. Think of a footnote marker in a text: It links the main text with the footnote text, although in this case the marker is a static linkthe reader must make the movement between text and footnote. In hypertext, the links are active: Selecting the link moves the reader to the linked text in some way. It is this dynamic aspect of presentation that is the principal difference between text and hypertext. An alternative term for hypertext which never gained the same currency was interactive documentation (Brown, 1986), and a recent paper used the term responsive text (Hillinger, 1990). ,.

If hypertext isn't a new idea, why has it recently become so popular? In fact, hypertext has been an idea waiting for technology to catch up with it. In order to implement active links, it is necessary to use a dynamic display medium such as a computer screen. Hence, in the 1960s in the research laboratories, several groups started using large mainframe computers in order to explore the potential of hypertext. Advances in computer technology have led to the development of the minicomputer and the microcomputer, making considerable computer power available to the individual user: the personal computer with so-called "user friendly" interfaces. On such computers, "popular" hypertext becomes feasible.

Hypermedia is presented as a further development of hypertext. As computers have moved from being able to present little more than uppercase text to being able to present information in a variety of communication media sound, graphics, videoso it is possible to link these media together using hypertext techniques, hence the term hypermedia. However, in the same way that a book can contain text, drawings, tables, photographs, or even pop-up models, so the distinction between hypertext and hypermedia is somewhat arbitrary. We will use either term to refer to a set of nodes of information that are dynamically linked.

By way of example, consider how information relating to the European Union (EU) could be presented. At the top level, the reader could be presented with a map of Europe and then be able to select various aspects of the EU or any particular member state for more information (see Fig. 21.1). This may take the form of a more detailed map showing the major cities that, when selected, showed some information about the city. Alternatively, the reader may be offered other information about the country, such as the currency, culture, audioclips of common words in the language such as please and thankyou, and so forth (see Figure 21-2). The city maps could offer sites of interest such as museums, local transport details, entertainment sites such as theaters, or even restaurants and pubs; they could include videoclips of the major tourist sites, on the beach or at the disco. Now the tourist "brochures" can feature live action and be interactive in a way that the present printed chapter cannot.

Figure 21-1. The top level of the Euro-Base hypertext, a wealth of information at the click of a button.

Figure 21-2. See and hear the sights of Europe.