UNIVERSAL
USABILITY IN PRACTICE UNIVERSAL
USABILITY IN PRACTICE
Introduction | Recommendations | Guidelines | Examples | Future | Resources | References
Kanta Jiwnani
Department
of Computer Science
University of Maryland
College Park, MD 20742 USA.
April 2001
Think Like: People who are disabled should be treated
the same as everybody else
If we work together by talking sharing resources and
teaching
we can break the
barriers
that disabled people face
and make things better
Written using Mayer-Johnson Symbols. [1]
This is an attitude that we as creators and citizens of this Web world need to adopt and follow.
Interface designers face a new challenge today, a challenge that when solved, will not only enable them to stretch the boundaries of the technical world but also open up the World Wide Web to cognitively disabled users. This population is both underserved and frequently misunderstood. With the advances of medical science, users who might never have left the hospital before are living independent, productive lives. As part of this goal, the Internet must be as accessible to them as other common elements of society. The Americans with Disabilities Act, mandates that employers must reasonably accommodate the disabilities of employees, and all public facilities should be accessible to individuals with disabilities.
The goal of this paper is to serve as a guideline for web-designers to understand and anticipate what problems people with cognitive and language impairment face when dealing with information, and how to successfully compensate for those problems on the World Wide Web. The rest of the paper is organized as follows. Section one describes the various types and causes of cognitive/language disabilities. Section two outlines the general recommendations for designing universally accessible websites. Section three gives more specific guidelines. Section four lists examples of successful websites. Section five offers some conclusions and suggestions for future work. Section six and seven provide with a list of useful resources.
To be able to do justice to this issue, we first need to define the problem and assess its magnitude. There is a wide variation of cognitive impairments that could be categorized as Memory, Perception, Problem-solving, and Conceptualizing disabilities. Memory disabilities include difficulty obtaining, recognizing, and retrieving information from short-term storage, as well as long-term and remote memory. Perception disabilities include difficulty digesting, attending to, and discriminating between sensory information. Difficulties in problem solving include recognizing the problem, identifying, choosing, and implementing solutions, and evaluation of outcome. Conceptual disabilities include difficulties with sequencing, generalizing previously learned information, categorizing, cause and effect, abstract concepts, as well as skill development and comprehension. Language impairments can cause functional disabilities of the latter, as well as of expression of written and/or spoken language.
Some
commonly known types and causes of cognitive/language impairment [2] are:
Mental
Retardation.
A person with an IQ below 70 (average IQ
is 100) having difficulty functioning independently is considered to be mentally
retarded. An estimated 1%
of Americans (2.4 million) are mentally retarded. For most, the cause is
unknown, although infections, Down's Syndrome, premature birth, birth trauma, or
lack of oxygen may all cause retardation.
Language
and Learning Disabilities
refers to a wide range of disorders manifested by
significant difficulties in listening, speaking, reading, writing, reasoning,
and calculating/integrating perceptual/cognitive information. They are presumed to be due to central nervous system dysfunction. It is estimated
that over 43% of children in special education programs in the U.S. (1.9
million) have some type of language and learning disability.
Head
Injury and Stroke.
Head injuries and stroke usually result in physical impairments,
cognitive impairments or both. There are approximately 400,000 to 600,000 people
with head injuries and approximately 2 million people who have suffered a
stroke.
Alzheimer's
Disease
is a degenerative disease that leads to progressive intellectual decline,
confusion and disorientation. 5% of Americans over 65 have Alzheimer's; 20% of
those above 80 have it.
Dementia
is a brain disease that results in the progressive loss of mental
functions, often beginning with memory, learning, attention and judgment
deficits. The underlying cause is obstruction of blood flow to the brain. Some
kinds of dementia are curable, while others are not. 5% of the population over
65 has severe dementia, with 10% having mild or moderate impairment. 30% of
those over 85 are affected.
A
person who is cognitively disabled may have:
Below average general intellectual functioning. The person often has difficulty with problem solving, reasoning skills, and understanding and using language.
Significant
delays in functioning. The person has difficulty with reading, math and writing
skills.
Deficiencies
in adaptive behavior or ability to interact with others, and in meeting the
demands and expectations of the environment.
Individuals with cognitive impairments may be prevented from accessing Web materials by insensitively designed pages . Adaptive browsers and assistive technology devices may themselves create barriers, as many are incapable of displaying common HTML features such as tables, frames and lists [3]. With the increasing use of these features to control layout, even more websites are becoming inaccessible to these users. To overcome these difficulties, we can help them by providing compensating interventions enabling augmented user access, or by changing the way the information is rendered through built-in browser options or Web page design enabling direct user access. These users may benefit from strategies that appeal to their learning strengths. This paper addresses the problems faced by these users and provides guidelines, general as well as specific, for the web-designers to make their websites universally accessible.
After defining the target population, we as web designers need to evaluate the needs of the cognitively disabled people not viewing them as handicapped or plain retarded, but as special people with special needs. What we need to understand here is that some of the basic functions of memory, thought process, speech which ordinary people use as swift reflexes, pose great problems for cognitively disabled people and we can help them by making this effort a little easier. So while we can just use the mouse as a multifunctional tool, with different functions of the right and left buttons, without even giving it a second thought, the brains of these disabled people may fail to differentiate the left from the right, or may not even register in their memory.
We need to use our knowledge and our expertise to enrich their lives by opening the windows of the world for them through the WWW. Evaluation of the improved designs may be difficult as the evaluations usually tend to be objective, but they are necessary not only for feedback and further improvement, but also, as an encouragement for web designers to continuously evolve better aids. It is necessary to design websites in ways that minimize the skills and abilities required to navigate them.
Difficulties commonly encountered by the cognitively disabled
Cognitively
disabled users may face difficulties while entering input or viewing the display
[4]. They may be unable to use the mouse or other traditional
input device with the same ease as other users. Also, complex
screen layouts (e.g., multiple window layouts) may confuse them. They have a
short attention span and are easily distracted when they review a screen
display. Thus it will be a good idea to have new or
urgent information highlighted.
Auditory output might seem confusing to them, or be difficult for them to understand. For websites with audio output, the presence of too much background noise may prevent them from effectively hearing information delivered auditorially. In addition, they might miss, auditory information that is short, rapid, not repeated, or not repeatable. The audio information may be too complex or sophisticated.
They also have difficulty with
sequential operations. They may not recall all the steps in the sequence, hence may get
confused or jumble the steps. The layout, labeling, or method of operating controls and other
input mechanisms of products can be confusing or unclear to these people. They
may encounter difficulties when they confront complex, cluttered control
layouts, with many, and/or a variety of types of controls like: difficulty
selecting from large sets; trouble remembering sequences; confusion with dual
controls; difficulty if required to rely solely on textual labels (especially if
abbreviations are used), and difficulty associating labels and controls; trouble
with timed responses which involve text. It is necessary to provide external
memory aids such as lists for these users.
The following conventions may be adapted to make the website more accessible:
Introduction to the website
Website designers should provide a plain language description of the website, the purpose of the site, and what can be done or learned here [5]. The introduction need not be extensive but it should be plain and straightforward so that a user will know what the website is about. Also, they should try to identify the pre-knowledge necessary for a user of the site and indicate the same either via an introduction page or a link to the external website that provides the beginner-level introduction to the subject. This will help the users to know what the website is about in a glance and allow them to read the basics if required. A site map should also be provided on the home page so the user can go the desired information directly.
Language and definitions
Provide definitions for unusual terms used [5]. There are some times when designers will need to define terms that may not be known to the average person. Define the term when it first appears. Add an extra sentence explicitly explaining what it means. This can be done naturally without interrupting the flow of the text. Another approach would be to provide a glossary of specialized terms and link the terms directly to the glossary using HTML anchors. Correct use of HTML markup features can expand the meaning of uncertain terms. Specifically, the ABBR and ACRONYM elements of HTML were designed for this kind of purpose and the TITLE element can also be used to provide a form of meta-information or "tool tip" depending on the browser used.
Navigation
There should be a simple way to backtrack or start over while navigating the website to reduce anxiety over failure in using it [5]. Similarly to provide confirmation to users, any activation of a control or change of state should have an accompanying auditory indication. The auditory output must be simple enough to draw attention of the user. Auditory output is explained in more detail in the next section. The website should have a uniform look across all levels to minimize cognitive load. Cognitively disabled have difficulty recollecting spellings of words so a spell-checker should be provided.
Use of graphics
The mainstay of information on the Internet is graphics which differentiates it from other methods of instruction, making it more accessible, and user-friendly. This is one aspect that can be suitably exploited to aid people with cognitive disadvantages. These users have difficulty reading and understanding complex textual prose. It is necessary to minimize the cognitive load while surfing the website. Use of graphics can enhance understanding [5]. The same information may be conveyed clearly and concisely. The Web is an information medium and the key is for information to be as multi-modal as possible - a term meaning simply "in different modes". The more ways to convey your content, the easier it becomes to communicate to others.
Graphics should be used whenever appropriate as long as those graphics help convey information. Graphics should give a sense, of what a page is all about at a glance. One should use easily understandable graphics. Also, use graphics for navigation whenever possible. Getting around a site is essential for using a site - it is a part of the minimal functionality that a web author needs to supply to users. Ensure the accessibility of the icons used. Understandability for one group of users should not come at the expense of accessibility for another, so appropriate labels and alternative content for graphics must be provided. Providing alternative content is necessary to solve problems such as accessibility for non-visual users and faster download times.
Care should be taken as not to overuse graphics. The information overload will increase with complex graphics. Avoid animated graphics and the use of overly large file sizes. Use animations and dynamic displays with care. They may help to illustrate concepts, but they may also change too quickly to be grasped. Consider providing adjustable speed, or let the user control the motion. For example, someone with a developmental disability may have found interesting web sites to visit, but have trouble returning to favorite sites by attempting to read a list of text options, like "Bookmarks." The necessity to read might be a barrier. In this situation, a helper might construct for the person a graphics-based interface that would allow the person to select options from a menu of pictures. Only use what's necessary to convey your meaning but don't be afraid to use graphics if it is necessary.
Cognitively disabled users frequently use third-party assistive technologies or a browser with built-in adaptive features to access the Web. Assistive technologies can be either software or hardware and are designed to compensate for individual impairments such as those used to convert text to speech, or those that provide alternatives for using a mouse to navigate Web pages. They are not all equally effective in accurately presenting Web document layout, however, and some simply do not handle many commonly used tags. This section summarizes the set of guidelines the designers should follow to help cognitively disabled users to access their websites with the same ease as any other users. These guidelines [4] [6] [9] [12] [15] can be categorized as those regarding input and display of information.
Input
1. For input, allow entry of a short code for a longer sequence. Simplify required sequences, limiting the number of steps. Cue required sequences of action. Display and vocalize a series of steps to accomplish a task. Where practical, limit the number of choices the user must make.
2.Use of multiple selection techniques for different users with different needs. Use direct selection techniques (i.e., selection techniques which require only a single, simple, non-time dependent movement to select) whenever possible. For example, for data entry, provide with a list of entries.
3.Provide an easy (as well as prominent and clear) exit that returns the user to the original starting point from any point in the sequence.
4.Standardize within the website by using same shape/color/icon/label for same function and action. Provide easy ways out of any situation. Incorporate pre-measuring methods whenever a quantifiable amount is required.
5.Commands and features should remain consistent from screen to screen.
6.Shorten menus.
7. Use pictographic or ideographic symbol system that helps such users to construct complex sentences, answer and ask questions.
Output
1.Use clear, uncluttered screens. Use simple screen layouts that provide the user with the option of viewing only one thing at a time. Simplify language. Provide adjustable display image size.
2. Design graphics and animation that contribute to, rather than distract. Accompany words with pictures or icons. Place textual description adjacent to the appropriate image.
3. Combined use of pictures and audio Prompts for navigation.
4. Use frequent audio feedback, both for error correction and positive reinforcers. Make the information available in audio format. Auditory information should be able to be presented on the visual display. Provide a volume adjustment (ideally, one with a visual volume indicator) through which the sound will be intelligible across the volume range. Make audio output or adjustable volume range as loud as practical. Present auditory information continuously or periodically until the desired message is confirmed and/or acted upon (spoken messages could automatically repeat or a mechanism could allow the user to ask that they be repeated). Provide auditory information (including, speech output, auditory cues and warnings) in visual, and tactile, form also. Before audio presentation, provide sounds or words that make the user attend. Keep auditory presentations brief. Include an audio-repeat function or button.
5. Use multisensory presentation of feedback information. Ensure that all messages and alerts remain on screen until they are dismissed.
6. Ensure compatibility with screen readers and screen magnification programs. These devices can ease access for users with cognitive impairments. Aural cascading style sheets (ACSS) now allow Web authors and users to specify aural properties (voice-family, speech-rate, pauses, pitches, volumes, sound effects, and speech properties) to represent these features.
7. Avoid applications whose text appears when the mouse cursor touches some point on the screen and then disappears when the cursor moves away from that point.
8. Use high contrast between text (or graphics) and background.
9. Present letters and other symbols on visual output in as large a display as possible. Ensure that there is spacing between letters of a words and lines, and distance between messages sufficient to enable users to discriminate. Make letters and other symbols on visual output as simple as possible (use sans serif typefaces for non-text lettering, e.g., labels, or dials).
10. Highlight key information. Arrange most important information at the beginning of written (but not spoken) text.
11. Present material in as many redundant forms as practical/ possible, or provide as many display options as possible.
12.Provide prompts to inform users about the source(s) of problems and lead them to actions to be taken to solve them. Use of "Error Minimization" features, such as removing buttons from the screen at times when use is inappropriate, should be done.
4. Examples of successful websites
This Web Access Symbol, produced by the CPB/WGBH National Center for Accessible Media (NCAM), indicates that this site contains accessibility features to accommodate the needs of users with disabilities. The power of the Web is in its universality. Access by everyone regardless of disability is an essential aspect." - Tim Berners-Lee, Director of W3C, creator of The World Wide Web. Examples of successful websites are listed below.
ADA
Technical Assistance Program
This website provides a special link to view the website with no frames.
In designing these pages, the ADA Program Assistance Coordinator has used guidelines from the Trace Research and Development Center's Unified Web Site Accessibility Guidelines [9] and the World Wide Web Consortium's Web Accessibility Initiative (WAI) [11].
All of the ADA-TA pages are Bobby compliant.
Additionally, all the ADA-TA pages have been checked for HTML 4.0 compliance using the World Wide Web Consortium's free HTML Validator Service.
Selecting the "D" next to the image at the top of each page will take
you to a description of the images used on that page.
All
things Web
This
website is designed with the viewpoint “Always
and in everything, remember your reader”. This site contains a text
index and a site map. ATW pages have been tested to ensure Double-A conformance
with the W3C's Web Content Accessibility Guidelines. ATW makes judicious use of
Cascading Style Sheets. All of the content pages in ATW have been validated
using the "transitional" HTML 4.0 DTD from the W3C. All the images in All
Things Web have been carefully selected and optimized to conserve
bandwidth, and to minimize download time. ATW is created and maintained using
the following suite of tools and services:
Editors:
WebWriter/2 and a now defunct version of Webber
HTML
preprocessing: Orb allows seamless embedding of metadata into individual
pages (which is exactly where it belongs).
HTML
validation: W3C's canonical HTML Validator
Graphics
optimization: LView Pro (Version 1b)
Links are checked monthly, courtesy of LinkAlarm
Artwire
Online Communication for the Arts. Arts Wire is a program of the New York Foundation for the Arts. They provide a link for the disabled users. Arts Wire makes every effort to assure that its Web content is accessible or usable by everyone. This includes people with text-based browsers, people with slow (modem) connections, people without Audio/Visual capabilities, people with helper applications missing, and people with disabilities. They provide
descriptions of graphics
an alternative text version
other universal access design principles as identified in the
Accessible HTML Guidelines posted at the Trace Center [9].
Brejcha
Personal and Disability Resource Site.
Designed
by a disabled who has put in lots of effort to make his website to be accessible
by all. For individuals needing larger text for more comfortable reading, he has
a large text page on screen magnifying hardware and software (including freeware
and shareware).
http://www.netreach.net/~abrejcha/welcome.htm
National Center to Improve Practice
(NCIP) In
Special Education Through Technology, Media and Materials.
NCIP has attempted to make this web site accessible for all users by following a wide range of emerging guidelines and recommendations for accessibility. Some of the design strategies they have used to make the information in this site accessible are listed.
Include textual links within web pages (e.g. next page, previous page) as well as a standard set of navigational buttons with accessible text
maintain a standard page layout throughout our site, enabling all users to navigate more easily
Provide alternate text and/or image tags for all images, pictures, and graphical bullets. These tags are visible if your browser supports the alt-text function
Avoid use of columns, tables, and image maps
Provide alternate versions of forms
Provide a transcript of all video clips
http://www2.edc.org/NCIP/Default.htm
The challenges that lie ahead of interface designers and practitioners working for cognitively disabled users are surmountable only if they combine their resources and experience. What differentiates cognitively disabled from other disabled users is that the exact problem and its extent is often not defined, unlike for other users such as visually impaired users. So evaluation of new innovations is necessary in order to judge the long-term benefits and applications of improved designs. This paper has presented some rudimentary guidelines for improvement in designing for the cognitively disabled. Technical know-how, legalities, and accessibility are primary hurdles that have been cleared by most designers. Now, web designers need to cement the loose ends and resist the temptations of too much simplification, for example using too many graphics that do not serve a purpose but end up adding to the confusion a cognitively disabled user faces.
Web designers need to specialize the products for the cognitively disabled according to their needs. For instance, a disabled user who uses a special device/program for daily scheduling so that he does not miss out on any of his routine tasks and can be independent, may need the schedule to be flexible in certain circumstances, for example when he is running late, so that he still completes all his tasks.
Users with memory problems may need reiteration of important points while visiting web pages, and also every link should be able to provide a detailed menu for using the page and revisiting the pages already seen. The information available on the web pages for the cognitively disabled is often extensive, which might be of no use to users with attention deficit disorders or short memory spans. For them, the information needs to be made more specific and in short capsules, made more interesting with the help of animated graphics, and use of numerical points wherever possible, so that the user can refer back to points of interest without having to go through the entire section again.
Practitioners
have to work in conjunction with interface designers. This will foster a healthy
two-way relationship where the practitioner with his knowledge of the cognitive
disorders and the difficulties faced by the cognitively handicapped users can
guide the designer to design more effectively, and he can benefit those in his
care by teaching the disabled users how to navigate the specially designed pages
with ease. Practitioners can also follow-up on the usability and accessibility
of web pages designed for the cognitively disabled users as they are in constant
contact with the users under their care. Practitioners can then help to lay down
specific guidelines for web designers allowing constant improvisation and
innovation.
To be able to strike the right balance, evaluation of the already existing technology is needed, by judging it's acceptance by the schools and institutions that cater to the these special users. A wide variety of assistive technology is available for cognitively disabled people. It would be a good idea for researchers to consider navigating a website with the help of assistive technology.
This section gives a list of resources available for cognitively disabled users.
AbilityHub Assistive Technology Solutions. Assistive Technology for people with a disability who find operating a computer difficult, maybe even impossible. This web site will direct you to adaptive equipment and alternative methods available for accessing computers.
ABLEDATA Assistive Technology Database. ABLEDATA is a free database of assistive technology and rehabilitation equipment. It lists more than 25,000 products from nearly 3,000 manufacturers and distributors. http://www.abledata.com/.
The Access Board. The U.S. Government's Access Board, the only federal agency with the primary mission of increasing accessibility for people with disabilities. They are working on recommendations for accessible government websites. http://www.access-board.gov/
Adaptive Technology Resource Center Technical Glossary. ATRC's technical glossary includes definitions of various types of adaptive technologies as well as descriptions of specific soft- and hardware. Contact information for the companies that produce these products is also included. http://www.utoronto.ca/atrc/reference/tech/techgloss.html
A-Prompt, developed by the University of Toronto and The Trace Research and Development Center, is a tool for Web authors that works with existing HTML editors. A-Prompt (Accessibility Prompt) has been developed to assist Web authors in improving the accessibility and usability of HTML documents. By checking Web pages for barriers to accessibility and making repairs to correct any problems, A-Prompt will ensure that you are reaching the widest possible audience. A-Prompt is based on the guidelines for accessibility which are created and maintained by the Web Access Initiative of the World Wide Web Consortium. http://aprompt.snow.utoronto.ca/
BETSIE, the BBC Education Text to Speech Internet Enhancer, is a package that can be installed on webservers which translates and deliver web pages in a more accessible form. The service is available to users on BBC sites, and can be implemented by webmasters on their own servers. http://www.bbc.co.uk/education/betsie/index.html
Building
web pages for disabled users
Bobby, created at CAST (Center for Applied Special Technology), is an HTML validation program designed to test accessibility and highlight nonstandard and incorrect HTML. http://www.cast.org/bobby/.
Closing the Gap. This website gives a list of Computer Products in Special Education and Rehabilitation. http://www.closingthegap.com/
Connecting
Canadians -- Persons with Disabilities' Guide to the Net. The Canadian
government's guide to computer and Internet use for Canadians with disabilities.
Digital
Canvas. The May issue of Open Studio: The Arts Online's web magazine features
extensive coverage of web accessibility and many terrific articles and links.
DO-IT (Disabilities, Opportunities, Internetworking and Technology) hosts a rich collection of resources, including links to Internet resources for accessible Web design. [2]. http://www.washington.edu/doit/
EASI's (Equal Access to Software and Information) Web site provides information related to serving patrons with disabilities including accessible Web design. http://www.isc.rit.edu/~easi/.
IBM's Special Needs Systems. IBM has developed both the Home Page Reader voice browser system and the Self Voicing Kit for increased accessibility of Java applications. http://www-3.ibm.com/able/index.html.
IT Equipment Accessibility Checklist. The Department of Justice created this checklist to help government agencies determine whether their information technology accommodations met the requirements of Section 508 of the Federal Rehabilitation Act. Worth looking at as a starting point in making work areas accessible. http://www.usdoj.gov/crt/508/itequip.html
Microsoft's Web
Accessibility Pages. Microsoft has a section describing web accessibility and
giving pointers to increasing your site's accessibility, as part of their accessibility site.
Products Provided by
Microsoft include keyboard filters, voice input aids, screen review utilities.
The National Center for Accessible Media (NCAM) promotes the use of a Web Access symbol and provides examples of accessible pages. NCAM also contains valuable resources on providing captions to streamed video resources. http://www.wgbh.org/wgbh/pages/ncam/webaccess/index.html
PURSUIT: Basic Skills in Assistive Technology. The PURSUIT program
encourages students with disabilities to "pursue their academic and
professional dreams," with a special emphasis on math, engineering and
computer science. This introductory lesson in assistive technology offers brief
discussions of the whys and hows of selecting appropriate technologies and basic
descriptions of technologies developed to support individuals with specific
disabilities. It also includes relevant legislative information.
Sun Microsystems'
Enabling Technologies Program. Sun's site on accessibility has, naturally, a
large emphasis on making accessible Java applications using Sun's Java
Accessibility API. http://www.sun.com/tech/access/
The Trace Research and Development Center provides resources for the design of accessible Web pages including applet and plug-in features. http://www.trace.wisc.edu/. TRACEBASE Database of Assistive Technology. Trace Research and Development Center created this database of assistive technology descriptions and product information. http://www.tracecenter.org/tcel/tbase/index.html
At WebABLE, our mission
is to make the Internet and World Wide Web accessible to people with
disabilities. To accomplish this mission, we provide accessibility technology
and services to corporate, government, educational, and non-profit clients.
www.webable.com. The
WebABLE! Library is a collection of books, press releases, white papers,
articles, plans, standards, reference guidelines, and journals that focus on
accessibility, assistive and adaptive technology for people with disabilities.
W3C's Web Accessibility Initiative outlines the strategies and tools for creating web sites that are highly usable. It has a set of Web Content Accessibility Guidelines, recommended techniques for web content accessibility and also a list of checkpoints. It also has a QuickTips Reference Card for web developers. http://www.w3.org/WAI/.
Yuri Rubinsky Foundation: WebAble database. The Yuri Rubinsky Foundation created this searchable database of resources on disabilities and accessibility. http://www.yuri.org/webable/search.html
[1] Symbol Statement from Healthy Living Network, http://www.in-hln.org.uk/symbstatement.html, Accessed on April 20th, 2001.
[2] "What Problems Do People with Disabilities Have? and Why?" http://trace.wisc.edu/docs/software_guidelines/software.pcs/disabil.htm. Accessed on April 20th, 2001.
[3] Judy Cossel Rice, "Designing Web Pages for Special Populations". http://www.byu.edu/ipt/rice/spec_pop/paper.html Accessed on April 20th, 2001.
[4] Ellen Francik, "STRATEGIES FOR PEOPLE WITH COGNITIVE DISABILITIES" http://www.igc.org/wid/text/tech/telecom/index.html. Accessed on April 20th, 2001.
[5] Kynn Bartlett, "Designing Pages Accessible to Limited Textual Comprehension Users" , http://aware.hwg.org/tips/Itcu.html Accessed on April 20th, 2001.
[6]
DO-IT: Disabilities, Opportunities, Internetworking & Technology. 1996.
DO-IT HTML Guidelines.
[7]
Fontaine, P. 1995. Writing Accessible HTML Documents. http://www.webable.com/htmlcode.html
[8]
Gunderson, J. World Wide Web Accessibility to People with Disabilities: A
Usability Perspective. http://www.staff.uiuc.edu/~jongund/access-overview.html.
[9]
National Center for Accessible Media (NCAM). Captioning and Audio description on
the Web. http://www.wgbh.org/wgbh/pages/captioncenter/.
[10]
Nielson, J. 1996. Accessible Design for Users with Disabilities. http://www.eu.sun.com/columns/alertbox/9610.html.
[11] Paciello, M., Rubinsky, Y. 1997. People with Disabilities Can't Access the Web. http://www.yuri.org/webable/mp-pwdca.html. Accessed on April 20th, 2001.
[12]
TRACE. Designing Universal/Accessible Web Sites. http://www.trace.wisc.edu/world/web/index.html.
[13]
TRACE. Designing a more usable world. http://trace.wisc.edu/world/
[14] Vanderheiden, G. Chisholm, W. A., Ewers, N. 1996. Design of HTML Pages to Increase Their Accessibility To Users With Disabilities.
http://www.trace.wisc.edu/text/guidelns/htmlgide/htmlgide.html. Accessed on April 20th, 2001.
[15]
World Wide Web Consortium. 1998. Web Accessibility Initiative (WAI). http://www.w3.org/WAI/
[16] http://www.webreference.com/. A collection of resources for professional web designers and site managers and contains useful information for anyone working on producing material for the Internet. It includes tools, reference material and articles, including many on accessibility issues. Accessed on April 20th, 2001.