DESIGN INTO PRODUCTION

Computer screens are not paper

Some characteristics of the screen include:

• landscape format, usually 4 units wide by 3 units high, rather than the upright A4 format generally used for paper
• poor resolution, typically 72 dots per inch, compared with between 300 dots per inch (office laser-printer) and 1200 dots per inch (professional litho) on paper
• weightless documents (there is no possibility of judging size, importance, reading time required, by weighing in the hand)
• details of typography and layout are not wholly under the control of the originator, so the reader cannot interpret the character of the document by (for example) associating Times with authority or Futura with modernity.
• the user has no prior knowledge of the likely structure of the document. It is not necessarily familiar like a book with an index, since hypertext links may take on almost any shape of structure their originator chooses
• hypertextual link-points intrude into the content

Designing for the screen

• Extended blocks of prose are inimical to screen-reading, since they require the user to scroll the text window. This is significantly slower than the movement of the eye in scanning an equivalent text on paper. Users must partially remove their attention from the text itself in order to attend to the mechanics of scrolling.
• Headlines tend to need repeating, because a main heading has disappeared off the top of the screen by the time the end-user gets to the paragraph to which it refers. We are probably unaware of the extent to which we use peripheral vision when reading paper, to remind ourselves of the context of the current item.
• If there are generic facilities for the user to, say, return to a contents screen, then this needs to be provided in a visible and convenient way on every screen, since at any moment, the user will not otherwise know where to look in order to find such a facility.
• Unlike documents for paper, it is often desirable to provide only the minimum necessary white space' between an item and the ones above and below it. The empty space which on paper provides a rest for the eye and mind, on screen simply increases the cognitive load on users by forcing them to hold text in their heads while the white space scrolls past. However, there is no need to fill the screen gratuitously screen-space is free. If all that is needed is a small set of links to other screens, for example, then generous use of white space around them is recommended.
• Interactive documents bring with them new notions of authorial good behaviour. Some authors of electronic texts are surprisingly casual about some issues. For example, it would be unusual in a paper document for there to be a chapter name in the Contents without there being a corresponding chapter, but many interactive documents have links' which link to nothing, or to a message saying Nothing developed here yet. Sorry.' This is the down-side of the loss of a sense of finiteness and closure associated with paper-based texts.
• When a Web site is conceived or designed on behalf of someone else, a number of issues arise which differ from those for traditional paper documents. For example:
  • clients cannot brief the designer so well, because they have seen few examples on which to base their specification
  • because of constant changes in the technologies used, what is possible changes during the life of the project
  • the site must be robust across different browsers and platforms
  • delivery varies from good when network traffic is low to appalling when it is high
  • differentials in costs are quite different from those for paper (see Cost differentials)

Graphics     Multimedia      Virtual Environments      Visualisation      Contents