When you design or modify Web sites to allow access to people with disabilities, you make the Web accessible. New Web sites and applications, however, are introducing new problems and barriers. There are complex graphics and multimedia applications that assistive technology simply has not solved. One solution to these new problems is to put accessibility in the hands of the Web developer and content author. Creating a Web site that is accessible by people with disabilities is relatively easy as long as the Web developer and author follow some basic guidelines.
Assistive technology is a piece of equipment or a software product that is used to increase, maintain, or assist the functional capabilities of individuals with disabilities. In short, it can be any device or technique that assists people in removing or reducing barriers and enhancing their daily activities. Assistive technologies include magnifiers, screen readers, closed captioning, keyboard enhancements, and highlighting software. Assistive technology uses the coding and content of your Web site and makes it accessible. This course is not designed to make you an "assistive technology" developer, but does provide steps and guidelines to follow that address the accessibility needs of users.
Meeting the standards of an accessible Web site first requires an awareness of the special needs of users who have disabilities. The four main categories of disabilities are visual, hearing, mobility, and cognitive and learning disabilities. Each person with a disability might encounter one or more barriers that can be eliminated or minimized by the Web developer, the browser, the assistive technology, or the underlying operating system software and hardware platform.
Visual
People with visual disabilities are individuals who are blind, have low vision, or have color blindness. People who are blind need text equivalents for the images used on the Web page, because they and their assistive screen reader technology cannot obtain the information from the image. A person who has a visual disability will not find the mouse useful because it requires hand and eye coordination. Instead, this person must navigate the Web page using only the keyboard. For example, the Tab key is used to move the focus to the item that needs to be selected. A screen reader then announces the item so the user knows where the focus is on the page. The user then presses the Enter key instead of "clicking" the mouse button. Those who have low vision need the assistance of a hardware or software magnifier to enlarge the text beyond simple font enlargement. People who are color blind or who have low vision benefit from good contrasting colors. When information is presented by color alone, a person who is color blind misses that information. Similarly, if information is presented using any attribute by itself (for example, contrast, depth, size, location, or font), a user who has low vision might not detect the difference.
Magnification might reformat the location, change the contrast, or distort the size and fonts of the text and objects on the Web page. It is best to use multiple attributes. For example, if both color and a fill pattern are used on different bars on a graph, they can be viewed in either color or black and white. Instead of using size attributes on the font element to denote a heading, the heading element should be used to correctly mark up a heading so that assistive technology can identify headings.
Hearing
People who are deaf or hard of hearing require visual representations of auditory information that the Web site provides. Solutions for these disabilities include closed captioning, blinking error messages, and transcripts of the spoken audio. The primary concern is to ensure that audio output information is provided in a redundant equivalent visual form.
Mobility
People with mobility disabilities have physical impairments that substantially limit movement and fine motor controls, such as lifting, walking, and typing. Mobility impaired individuals experience difficulties in using the computer's input devices and in handling storage media. Solutions for persons with mobility disabilities include switches, latches, and controls that are easy to manipulate, and diskettes and media that are easy to insert and remove.
Additional solutions include alternate input capabilities, such as voice input or the ability to enter information at the user's own pace. For example, sequences of keystrokes can be typed, one at a time, rather than simultaneously as in Ctrl+Alt+Del. Many of these needs are supported by assistive technology, operating systems, and hardware platforms. Furthermore, making the Web site accessible will make it more compatible with voice input and control technologies.
Cognitive and learning disabilities
People with cognitive or learning disabilities, such as dyslexia and short-term memory deficit, need more general solutions, which include providing a consistent design and using simplified language. For example, by using a template, a Web developer can reuse the same layout and design for each page, so a person with a cognitive disability can more easily navigate through a Web site. People with cognitive or learning disabilities can also benefit from redundant input, such as providing both an audio file and a transcript of a video. By simultaneously viewing the text and hearing it read aloud, they can take advantage of both auditory and visual skills to comprehend the material better.
Last updated, September 04, 2007