People with Disabilities and the Web
- Visual Disabilities
- Auditory Disabilities
- Physical Disabilities
- Speech Disabilities
- Cognitive and Neurological Disabilities
- Other Disabilities to Consider
Visual disabilities include blindness, low vision and color blindness. Users with visual disabilities may use one or more of the following assistive technologies:
Screen readers – These read what is displayed on the screen and direct it either to audio output or to refreshable Braille. Each brand of screen reader is different and will read the screen differently. Examples include JAWS, Windows-Eyes and HAL.
Screen Magnifiers – These tools magnify a portion of the screen for easier viewing; however, magnifying the screen reduces the viewable area of the page, resulting in the need for more vertical and horizontal scrolling. Some screen magnifiers have the ability to show two views of the screen, one magnified and the other at normal size for navigation. Examples include ZoomText and Lunar Screen Magnifier.
Braille and Refreshable Braille – This technology employs a system of six to eight raised dots in various patterns which represent letters and numbers. Refreshable Braille (used with screen readers) uses a mechanical device to raise and lower the dots to allow any Braille characters to be displayed as the screen reader reads down the page. More information may be found at Deafblind.com.
Tabbing – With this method, users press the "Tab" key to move through a list of links or headers or other list items on a page. This can help people who are blind to navigate through a page quickly without having to wait for the screen reader to read everything on the page.
Speech synthesis – This technology produces audio output from screen readers or voice browsers.
Voice browsers – These are systems that allow voice-driven navigation, some with both voice input and voice output, and some allowing telephone-based web access.
Text Browsers – Technologies such as Lynx display only the text of a page, without any graphical elements.
Users with these visual disabilities may face the following problems with inaccessible sites:
- Images without alternative text, or with meaningless alternative text
- Complex images, such as graphs, that are not described
- Video without text or audio transcriptions
- Complex tables that do not make sense when read cell by cell
- Frames without "NOFRAME" alternatives, or which lack meaningful names
- Browsers and authoring tools lacking keyboard shortcuts for all commands
- Browsers and authoring tools that do not use standard applications or programmer interfaces for the operating system they are based in, such as "Ctrl-p" always being print
- Document formats such as PDF which can be hard or even impossible for screen readers to interpret
The same barriers as listed for blindness, plus the following:
- Web pages with absolute font sizes that do not change (enlarge or reduce) easily
- Web pages that, because of inconsistent layout, are difficult to navigate when enlarged, due to loss of surrounding context
- Web pages (or images on web pages) with poor contrast, and whose contrast cannot be easily changed through user override of author style sheets
- Text presented as images, which prevents wrapping to the next line when enlarged
- Color alone is used to identify something important, such as red text to show which items are unavailable in a library catalog
- Poor contrast between text and background, such as dark gray text on a black background
- Browsers that do not support user override of designer's style sheets
Auditory disabilities include any degree of hearing loss, from mild to total deafness. Users with various degrees of hearing loss may require captioning or text transcripts for all audio media. Another important accessibility feature is built-in visual notifications, alerts of warnings or error messages that might otherwise be issued by sound.
Users with auditory disabilities may face the following problems with inaccessible sites:
- Lack of captions or transcripts of audio
- Lack of content-related images in pages full of text, which can slow comprehension for people whose primary form of communication may be a sign language instead of a written/spoken language
- Lack of clear and simple language
- Requirements for voice input on web sites
Physical disabilities include anything that involves limited or lack of motor control in the hands and arms. Some users with physical disabilities may use alternative keyboards or switches. These items include keyboards with extra-small or extra-large key spacing, keyboards that allow only one button to be pressed at a time, on-screen keyboards, eye-gaze keyboards and sip-and-puff switches. Users of these alternatives are often dependent on web-based applications which may be operated entirely from a keyboard without a mouse. More information and examples may be found at the Ergonomic Sciences Corporation's page on Alternative Keyboards & Input Devices. Along with the alternative keyboards, users may need to use a head or mouth stick as an input method. Other users with physical disabilities may rely on speech-recognition software, such as Dragon Naturally Speaking, as an alternative input method to a traditional keyboard.
Users with physical disabilities may face the following problems with inaccessible sites:
- Time-limited response options on web pages
- Browsers and authoring tools that do not support keyboard alternatives for mouse commands
- Forms that may not be tabbed through in a logical order
Speech disabilities include any type of problems with speaking. Users with speech disabilities encounter problems with web sites that require voice-based interaction and have no alternative input mode.
Cognitive and neurological disabilities include a wide range of disabilities that can cause any number of problems with web use. Many assistive technologies used by those who are blind may also be utilized by those with cognitive or neurological disabilities. For example, users with dyslexia may use a screen reader/voice-synthesis combination to read the content of a site so they need not struggle with reading large blocks of text. Being able to tab through links and other elements may also help. Text supplemented by descriptive images can also help users with cognitive and neurological disabilities. For example, text directions for how to cook pasta can be supplemented with images for each step.
Users with cognitive and/or neurological disabilities may face the following problems with inaccessible sites:
Visual and Auditory Perception
Lack of alternative modalities for information on web sites; for instance, no alternative text that can be converted to audio to supplement visuals, or the lack of captions for audio
Attention Deficit Disorder
- Distracting visual or audio elements that cannot easily be turned off
- Lack of clear and consistent organization of web sites
- Use of unnecessarily complex language on web sites
- Lack of graphics on web sites
- Lack of clear or consistent organization of web sites
Lack of clear or consistent organization of web sites
Mental Health Disabilities
- Distracting visual or audio elements that cannot easily be turned off
- Web pages with absolute font sizes that do not enlarge easily
Use of visual or audio frequencies that may trigger seizures
- Multiple Disabilities – Varying combinations of disabilities will create different needs and also more potential for barriers to affect Web use.
- Age-related Conditions – Over time, different barriers can affect Web use as physical conditions worsen.