There are many people who need to be able to use standard software programs in their jobs, schools or homes but are unable to because of the design of the programs or their interfaces. These people, because of accident, illness, congenital condition or aging have reduced visual, hearing, physical or cognitive/language abilities. The current estimate of people with disabilities is over 40 million people -- a sizable portion of our population.
Making computers and software accessible to people with disabilities is not just the responsibility of application software developers. In fact there is only so much of the problem that can be address ate the application software level. System software manufacturers and 3rd party disability access software and hardware developers also need to play an important role.
The purpose of these guidelines is to document what application developers can do (or need to do) in order to make their software accessible and usable by people who have disabilities or reduced abilities due to aging.
The guidelines document does this by providing information on the problems faced by people with disabilities in using current software and documenting ways in which application software can be made more accessible and usable by them. The document also describes the roles of the other players (system software developers, 3rd party developers etc.) in this process along with the types of access modifications available from them.
As you read the guidelines, you will also see that the recommendations can increase the usability of the software to people without disabilities as well. In some cases the recommendations make the programs easier to use. In other cases they increase the ability of the software to work with other software, with scripting utilities, or with alternate input (e.g., voice input) or output (e.g., speech output) technologies.
Basically, making application software more accessible consists
of three complementary components:
1. Designing your software so that it is as usable as possible to the greatest number of people - without requiring them to use special adaptive software or hardware. (This is referred to as Direct Accessibility).
2. Designing your software in such a way that it will work with
special access features built into the operating system or attached
to it by users who require them.
(i.e., Compatibility with operating system or third-party access features / software / devices for those people who will not be able to use your software directly.)
3. Making sure that your documentation, training, and customer support systems are accessible.
A brief sumnmary of the guidelines by disability area follows.
People with physical disabilities can have a wide range of abilities and limitations. Some people may have complete paralysis below the waist but may have no disability at all with their upper body. Others may have weakness overall. Some may have very limited range of motion, but may have very fine movement control within that range. Others may have little control of any of their limbs, or may have uncontrolled, sporadic movements which accompany their purposeful movements. Some with arthritis may find that hand and other joint movement is both physically limited and limited by pain.
A physical disability, by itself, does not usually affect a person's ability to perceive information displayed on the computer screen. Access is generally dependent on being able to manipulate the interface.
Therefore, you can increase the accessibility of your software (both direct and via access features/software and hardware)
Many users with hearing impairments need to have some method for adjusting the volume or for coupling the sounds more directly to their hearing aids. Both of these are hardware considerations and can be met with systems having volume controls and headphone or audio jacks. Users who have more severe hearing impairments may also use a combination of these techniques, as well as techniques for people who are deaf. Such techniques generally involve the visual display of auditory information.
Therefore, you can increase the accessibility of your software to users with hearing impairments
In addition, you should make sure that product support people are reachable via Text Telephones (also called TDD's or Telecommunications Devices for the Deaf).
You can increase the compatibility of your software with access features/software
People with low vision may have any one of a number of problems with their vision ranging from poor acuity (blurred or fogged vision) to loss of all central vision (only see with edges of their eyes) to tunnel vision (like looking through a tube or soda straw) to loss of vision in different parts of their visual field, as well as other problems (glare, night blindness, etc.).
For people with low vision, a common way to access the information on the screen is to enlarge or otherwise enhance the current area of focus. Given this, you can increase the direct accessibility of your software
In addition, you can increase the compatibility of your software with low vision access features/software
Many people who are legally blind have some residual vision. This may vary from just an ability to perceive light to an ability to view things that are magnified. The best design is for this group is therefore one that doesn't assume any vision but allows a person to make use of whatever residual vision they may have.
Access by people who are blind is usually accomplished using special screen reading software to access and read the contents of the screen, which is then sent to a voice synthesizer or dynamic braille display.
On computers which use a graphic user interface this is a bit tricky, but there are a number of things that application software developers can do to make it possible for people using screen readers to detect and figure out what is on the screen. These include
You can also increase the compatibility of your software with screen readers using the following considerations:
Since screen readers can only read text (or give names to separately identifiable icons or tools) it is a good idea to:
Finally, you can make your documentation and training materials more accessible
This is perhaps one of the most difficult areas to address. Part of the difficulty lies in the tremendous diversity that this category represents. It includes individuals with general processing difficulties (mental retardation, brain injury, etc.), people with very specific types of deficits (short term memory, inability to remember proper names, etc.), learning disabilities, language delays, and more. In addition, the range of impairment within each of the categories can (like all disabilities) vary from minimal to severe, with all points in between. In general, software that is designed to be very user friendly can facilitate access to people with language or cognitive impairments.
Somewhat more specifically, you can increase the accessibility of your software
In addition, because print disabilities are more common among people with language and cognitive impairments, you can increase the accessibility of your software by ensuring that it is compatible with screen reading software. (See the section titled "For People Who Are Blind," above.)
Finally, you can increase the overall accessibility of your software
This document is hosted on the Trace R&D Center Web site. Please visit our home page for the latest information about Designing a More Usable World - for All.