According to the regular Georgia Tech surveys (GVU, 1998), about 8% of Web users have a disability, and nearly half of them are blind or visually impaired. Creating Web documents and sites that are accessible to the visually impaired student should therefore be an important objective for all departments in higher education institutions that rely on Web-based information.
An increasing amount of student information is derived from Web sites. There are numerous virtual field courses on the Internet, and many departments of geography have their own Web server which stores information that is used to brief students on fieldwork and fieldcourses. With this in mind, it is important to review the effectiveness of this online resource for the visually impaired student. (See the Computer Applications document for a complementary discussion of the visual interface of modern desktop software.)
The Web is almost entirely a visual experience. Not only do students have to navigate their way around the Web using a graphical user interface (GUI), but the Web pages they encounter are likely to contain graphical images, and are laid out in ways that make design sense — i.e. visual design sense — to those who created them. Where a document consists largely of text, readability issues come rapidly into play (Nielson, 2000); where a document includes graphics, accessibility issues become more significant, though even poorly designed text can prove troublesome for visually impaired students.
According to the RNIB,
"an accessible Web site is one that can be accessed by everyone" (RNIB, 2001). Accessibility is the degree to which a Web document or Web site can be successfully 'read' by a person with some kind of impairment. In this guide, accessibility refers to the success with which a blind or visually impaired student can use a Web site or document, and accessible design is the skill of creating a Web site or document that ensures accessibility for blind or visually impaired students.
What, then, can be done to ensure that Web documents created for, or recommended to, visually impaired students are fully accessible to them? Perhaps the first principle to acknowledge is that reading from screen can be visually uncomfortable or stressful for many people, not just for those with a recognised visual impairment. Here are some general usage rules for visually impaired students that will help them minimise eye discomfort (Williams, 1998):
Here are some general design rules that can help to ensure that the visually impaired student will be able to read from the screen:
It should be noted that many of these guidelines will make it easier for everyone to read Web documents from screen.
Visual impairments provide specific challenges to Web designers, over and beyond those relating to users with normal sight. The following notes summarise some of the best practice advocated on the Web itself.
Perhaps the simplest approach when designing Web pages for students with poor visual acuity is to use a large font size for all text. An example of a Web site that does this is the National Library for the Bind site at: www.nlbuk.org/navigator.html. A more flexible approach is to allow the user to change text fonts, text colours font sizes and background colours to suit their visual capability. Here are some useful examples:
Even if Web designers do not provide this kind of flexibility (and few do), students can readily change the default font size on their browser to improve the readability of the documents they are reading. Here is how it is done in the two most commonly used browsers:
In each case, the new setting overrides that of the document itself, and stays in force until it is changed again.
Another design tip is to avoid using multiple frames, as these reduce the amount of space available for enlarged text. If frames are unavoidable, then they should be arranged horizontally across the screen, to reduce the need for horizontal scrolling should the text size be increased.
Most blind computer users rely on 'screen reading' software, which extracts the text in a Web document so it can be spoken by a speech synthesiser or passed to a braille display. (See the Assistive Technology document for details.) For these to work effectively, it is important to ensure that all components in the Web document are represented with suitable text. For example, image descriptions should be provided using the 'alt=' tag, and links to other documents should be provided in text form if image links are adopted. Splitting up a document into vertical columns can be problematic for less sophisticated screen readers, which read from left to right across the document.
Colour blindness, or more generally colour deficiency, is common amongst males (affecting 8% of the population), but less common amongst females (affecting only 0.5% of the population) (Hess, 2000). Although there are several forms of colour deficiency, each involving a weakness in sensitivity to a particular colour (e.g. protanopia, protanomalia, deuteranopia and tritanopia), few affect more than a small fraction of the male population. The most common condition is deuteranomalia, a weakness in green sensitivity, which affects 4.9% of the male population.
There are both general and specific ways of designing Web documents to ensure that readers with colour deficiencies will not be disadvantaged (Lowney, 1998; Arditi, 1999):
For detailed guidance on the technical issues behind the design of 'safe' Web colours for those with colour-deficient vision, see the discussion and tools at Christine Rigden's BT site (Rigden, 2000).
For their part, users should ensure that the colour contrast is set relatively high on their computer monitor. (Microsoft Windows also provides the ability to switch to a High Contrast setting from the Control Panel.)
Because of the growing importance of the Web as an information dissemination medium, several individuals and organisations have attempted to put together sets of guidelines for the design of accessible Web documents and sites. The premier organisation that defines appropriate accessibility standards for Web sites is the World Wide Web Consortium (W3C), which has for many years been running a Web Accessibility Initiative (WAI). This has published the Web Content Accessibility Guidelines (WCAG), which are based on expert international contributions. (An extremely useful summary checklist is available from the W3C, and another from the Iowa Department for the Blind at http://www.blind.state.ia.us/access/tips.htm.)
In the UK, the Royal National Institute for the Blind (RNIB) provides its own guidelines for accessible Web design (http://www.rnib.org.uk/digital/hints.htm), and in the USA the National Federation of the Blind outlines eight principles for designing accessible Web pages (http://www.nfb.org/tech/webacc.htm). The Director of Technology at the National Federation of the Blind has also produced a similar set of guidelines and suggestions for making Web sites accessible to VI users (Chong, 2000).
Several commercial software developers have instigated broad initiatives aimed at making modern desktop software more accessible to the blind or visually impaired, including:
A number of organisations and individuals offer Web document testing facilities on the Internet, to see how well they conform to accessibility guidelines. One example is Bobby, which is a free service to members of CAST (Center for Applied Special Technology) which helps identify and repair significant barriers to access by individuals with disabilities. Web documents may be submitted to Bobby for vetting, or the software may be downloaded to a user's PC for testing entire Web sites. Sites that pass the tests may display a 'Bobby approved' icon. A somewhat broader test is provided by HTML checking services (there are free ones on the Web at: http://validator.w3.org/, and www.htmlhelp.com/links/validators.htm), which will identify non-standard HTML that may cause problems for screen readers.
As a class exercise, identify and evaluate the accessibility of a selection of virtual fieldcourse sites on the Web. (Some examples are listed in Shepherd, 1999.) If they fail to match up to the standards and principles and standards reviewed above, consider contacting the site authors with a view to improving them.
Page updated 14 December 2001
GDN pages maintained by Phil Gravestock
© Geography Discipline Network/authors, 2001
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