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Authoring and Design for the WWW


User-centred design

Designing what?

The aspects of Web sites about which design decisions can be taken include the... In a well-designed site, all these aspects will be considered with the user's perspective in mind.

The scope of user-centred design

The design of computer systems which are effective and congenial for users is a huge discipline in its own right. SIGCHI, the Special Interest Group for Computer-Human Interaction (see Web Resources, p110), has become the largest interest group of the Association for Computing Machinery, reflecting a shift in attitude across the whole computing industry towards making products for people rather than expecting people to adapt their behaviour to products.

In this handbook we can do no more than introduce some of the key concepts of user-centred design and show how they can be applied to design for the Web. If we have emphasised the role of the user rather than the publisher in relation to all Web materials, this is not because the objectives and needs of the publisher are not important, but because these objectives can themselves best be served by aiming for a user who is stimulated and rewarded.

Constraints and the freedom to get things wrong

In the early days of the Web, only some aspects of site design were subject to any sort of design decisions. While the overall structure of linked pages, the language style and voice, and the information structure within pages were all definable, many aspects of the visual style and the user's interaction were effectively controlled by the limitations of HTML and the decisions made in advance in the design of browser packages. This meant that, to a certain extent, authors and publishers could apply their general knowledge of effective communication to the new medium.

Now the Web is becoming a richer mixture of media, and the range of possible interactions is greatly increased by developments in browsers and the provision of component technologies through the use of plug-ins.

For those wishing to take advantage of this richness, there are obligations to produce sites which are genuinely effective and enjoyable for users. The more possibilities there are, the more scope there is for making an unusable, cacophonous site. It is likely that specialist expertise in interaction design will be needed.

Some core principles of user-centred design

User-centred design has been summarised crudely as ensuring that 1 the user can figure out what to do, and 2 the user can tell what is going on. These simple aims are not always as easy to achieve as they might seem.

Weaknesses of design tend to arise in the following areas

Affordances are those aspects of a design which make it self-explanatory. For example, a poorly designed photocopier will not show where the blank paper should be inserted or how exactly it should be placed in the machine. In a Web document, one can find hypertext triggers which look like ordinary text or graphics, or conversely, text and graphics which are not active, but which appear to be!

Mappings are the visible relationships between parts of a system, or between the system and the user. Among systems with poor object-to- object mappings, a classic example is the cooker-top which has a set of heat rings arranged in a square but a set of controls for them arranged in a straight line. Labels then become essential to clarify the relationship between the controls and the objects. A Web example of poor mapping is a graphical map of a site which shows the various pages in some particular spatial configuration, but where this spatial model is subverted by the use of arrows pointing in various incompatible directions within the individual pages.

Feedback is the means by which we know, for example, that a car engine is running because we can hear it (incidental feedback) or that a steam-boiler is in a dangerous condition because a whistle is blowing (constructed feedback). In computer systems, almost all feedback must be constructed by the system designers.

The provision of feedback has not hitherto been a problem in the design of Web pages, since for simple HTML documents most of the necessary feedback has been provided in the design of the browsers. For example, in Netscape:

Such feedback is taken care of by the design of the browser, but when Web publishers incorporate other forms of interaction in their pages, for example as Shockwave components, then it is the responsibility of the designer to provide similar forms of feedback.


If a control panel is provided as a navigation device, then users must know:
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