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The X-Windows Accessibility Conquest – Developing for People with Disabilities

Mark E. Novak
Project Engineer, Trace R&D Center
(608) 262-6966, (608) 263-5408 (tdd)

Michael G. Paciello
President, The Paciello Group, LLP
(603) 882-4122


When a statement such as the one that appeared in the November-December 1996 issue of the “The X Journal” is made, eyebrows are raised. A comment regarding GUI's and computing noted that, “GUI's are the Model T Fords of our industry: they’ve made computers accessible to everyone.” A powerful statement that unfortunately falls dramatically short of reality. The fact is, GUI's are not accessible to everyone! Rather, it is an established fact that GUI's have imposed significant interface barriers to individuals with disabilities, particularly users who are blind or visually impaired.

Access for People With Disabilities?

What follows is the first of a 4-part series of articles introducing GUI and Unix developers to the world of computing for people with disabilities. In this issue, you will be introduced to common terminology and the concept of access systems.

Future articles will focus on key features, utilities, and applications already available within UNIX and it’s associated GUI's Each article will contain numerous code examples and illustrations. Additionally, hardware designs on various computer platforms, as well as guidelines for making products more accessible will be provided.

The goal of this series is twofold: a) To build awareness around the issues of computing and people with disabilities and b) To stimulate research, design, and development of Unix interfaces that will ensure access to those environments for all people.

Why the Need for Disability Awareness?

It has been estimated that over 30 million people in the United States have disabilities or functional limitations (of which a major cause is aging) [KS89]. In addition, as the post World War II Baby Boom generation ages, the trend towards an aging consumer population with age-related functional limitations is increasing. While estimates do vary, individuals who are disabled or have functional limitations as a result of injury, illness or aging, ranges from 12 to 20% of the population. However, when dealing with age alone, for those surviving to age 65, the number who will have functional limitations rises to 45% of the population according to U.S. statistics [Van90].

The seriousness implied by these significant percentages should not go unnoticed by the employer and consumer mass markets. In his 1990 paper, “Thirty-Something Million: Should They Be Exceptions?” Dr. Gregg Vanderheiden provided an in depth report regarding the growing population of people with disabilities and aging. Dr. Vanderheiden concluded that situations involving simple changes in design with the disabled in mind successfully benefit everyone for little or no cost, and also addresses the much larger economic cost of not implementing accessible design at all [Van90].

What is a Disability?

Take a moment and try to think of someone you know who has a disability. You may think of someone who is deaf, possibly in a wheelchair, or perhaps blind. Interestingly, the specific causes and types of disability vary widely. For the sake of clarity, disabilities are usually categorized into the following four groups or areas of impairment:

It should be noted that this sort of “categorization” doesn’t begin to cover the specific causes and/or range of problems associated within the impairment groups. It should also be noted that while trying to provide a brief description of the major causes of disabilities, some persons with certain disabilities may cross multiple categories. For example, a person who has experienced a head injury and stroke may have paralysis and memory problems. As a result, it is likely that their range of disabilities includes physical and cognitive impairment.

One final, yet important notation: Not all types of disabilities are necessarily easy to identify. In some instances a person with a seizure disorder may not appear to have a disability. However, recent studies have verified that some seizures are triggered by a blinking computer cursor or intense screen flicker.

This highlights another vital point namely, that it is virtually impossible to design a completely accessible computing environment.

To gain a basic understanding of the different kinds of disability, a description of the major categories of disabilities are provided in the following sections.

Physical Impairments

People with physical impairments probably represent the largest range of specific disability types. Individuals with a physical impairment may have difficulty with musculoskeletal control, weakness, and fatigue. Also, they may have neurosensory musculoskeletal dysfunction (e.g., walking, talking, sensing, grasping, reaching) and/or combinations of these activities which require multiple simultaneous actions, such as turning and pushing (e.g., opening of a door using a door knob).

Some major causes of physical impairments include:

Visual Impairments

The visual impairment group represents people with limited or low vision as well as people who are legally blind. There are an estimated 8.6 million people with visual impairments in the United States of which approximately 580,000 are legally blind. A large percentage of the visually impaired population is elderly.

Visual displays and other visual output cause the most trouble for people with visual impairments. The recent popularity of computer operating systems that employ a graphic or graphical user interface (e.g., GUI's) are particularly troubling to individuals who are blind, since GUI's require the use of eye-to-hand coordination to operate the mouse. Also, things many of us take for granted such as operating instructions, on-line help manuals, and printed documentation may be difficult to read or unusable at best for someone with a visual impairment.

Many people with visual impairments still have some visual capability and can read with the assistance of magnifiers, brighter lighting, larger lettering using sans-serif typefaces, and high contrast coloring.

Hearing Impairments

The hearing impairment group would represent people who are hard of hearing, as well as people who are deaf. Approximately 22 million people in the United States have a hearing impairment making it one of the most prevalent disabilities. As with visual impairments, hearing impairments can be found in all age groups, but loss of hearing acuity is part of the natural aging process.

Individuals with a hearing impairment have difficulty using products which provide auditory information (e.g., movie sound track). The presentation of auditory information redundantly in visual or alternative format (e.g., closed captions) or the use of audio amplification devices can sometimes help compensate for the loss of hearing.

Cognitive/Language Impairments
Perhaps the least understood of the four major areas of disabilities are the cognitive/language impairments. Individuals with cognitive impairments typically include memory, perception, problem-solving, and conceptualizing disabilities. Someone with a cognitive impairment may be unable to remember or to organize their thoughts (e.g., Alzheimer’s disease, dementia) or they may have severe retardation.

Language impairments can cause difficulty in comprehension, expression of written and/or spoken language. Terms such as expressive or receptive aphasia and dyslexia are often associated with language impairments.

Providing “Access Systems” to Computers for Individuals with Disabilities

Accessibility refers to the ability of people to use products and interfaces within their daily lives. For nearly as long as the concept of a “personal” computer has been around, there has also been a need to provide access systems for individuals with disabilities. Indeed, an entire industry has grown parallel to the personal computer industry attempting to provide accessible solutions and using terms like “adaptive or assistive technology” (AT).

Using AT, an individual with a visual impairment may require screen magnification software that enlarges the character fonts and graphics on the screen for easier viewing. Another individual who is completely blind may rely on screen reading software that provides audible output of the visual events on the screen. Other blind persons use a Braille device that sends input to and receives information from the computer.

An individual who is a quadriplegic might utilize AT by wearing a headband that contains an ultrasonic transducer and allows them to manipulate the mouse cursor and thus circumventing any need to use a mouse. In another setting, people with reduced hearing capabilities may instruct their favorite multimedia application to include text output or “captions”, as they attempt to listen to the melody.

Not all access systems or assistive technology need be equated with providing access for individuals with disabilities. Generally speaking, advancements in AT are often just as advantageous for persons without disabilities. For example, many people use library computers and listen to audio output by plugging a pair of headphones into the audio output jack. That same audio output jack can provide audio output for a blind individual. The addition of decoder chips in televisions to provide closed captioning for the hearing impaired has also found its way into the classroom to assist in teaching language skills.

Implementing GUI Accessibility on Unix Platforms

During the Fall of 1992, a group of software engineers with varied educational and professional backgrounds formed a collaborative working group called the Disabilities Access Committee for X (DACx). The charter of this group was clear: Make the X Window system accessible to people with disabilities.

As a result of their work, X users with disabilities have immediate access to a set of built in features including keyboard enhancements for users with physical impairments, screen reader features for the blind, screen magnification for low vision users, and enhanced visual cues for the deaf. How does all of this work? Watch for part two of this series.


It’s quite obvious that when Henry Ford designed the Model T, his design criteria was based on a minimum set of user requirements: the abilities to see, hear, and touch. Similarly, computing environments include a set of design requirements that take into consideration the needs of the user.

Creating an interface that is truly accessible to all persons, including people with disabilities, is a feat yet to be accomplished. In order for a networked based, graphics window system like “X” to achieve accessibility and be completely functional, operational, and usable, the optimal computing environment should adapt to the user rather than the user adapting to the environment.

In the meantime, if you are involved in the design or development computer software or hardware, we challenge you to consider some of this information and ask yourself whether or not your product is as accessible as it could be. Several sites that can provide you with more information regarding disability, accessibility, AT, and universal design are listed below.

Additionally, please consider the following reference that will provide you with information on the different types of disabilities and issues surrounding access systems:


[KS89] L. E. Kraus, S. Stoddard, “Chartbook on disability in the United States: An InfoUse report.” Washington, DC: U.S. Department of Education, National Institute on Disability and Rehabilitation Research, 1989.

[Van90] G.C. Vanderheiden. “Thirty-Something Million: Should They Be Exceptions?” Human Factors, 32(4), pp.383-396, 1990.


This article is funded in part by the National Institute on Disability and Rehabilitation Research (NIDRR), U.S. Department of Education, under grant #H133E30012.

Copyright 2002 The Paciello Group