Typically, using a computer means being able to type on a keyboard, see and read the screen, control and hear auditory signals. However, not everyone is able to perform these tasks for various reasons. People with limited hand function and control, visual impairments and blindness, hearing impairments and deafness, and learning disabilities, may require accommodation to access information of the Internet.

Assistive (or adaptive) technology is specialized computer hardware and software applications that enable these individuals to use a computer. Understanding what technologies individuals with disabilities use helps to appreciate the barriers these individuals face when using the Internet. This will shed some light on the need for accessible web design.

Below broad categories of assistive technology are briefly described, as well as the strengths and weaknesses of each technology.

1. Screen Readers

• Generally used by individuals with visual impairments or learning disabilities.
• Interpret what is displayed on screen and directs it either to a speech synthesizer for audio output or to a refreshable Braille display for tactile output.
• Enables individuals to use computers independently. This means they can independently read newspapers, books, articles, and anything online without needing someone else to read it aloud to them.
• However, older screen readers use the rendered version of a document, so the document order or structure may be lost (i.e. when tables are used for layout) and the output may be confusing. Also, screen readers cannot interpret images or graphs - any information presented in these formats is not available to those using screen readers. Lastly, the synthesized speech is not always clear and often mispronounces words.

2. Refreshable Braille Displays

• Technology used by individuals who are blind.
• Devices in which pins raise and lower to display Braille - a tactile system using raised dots to represent letters and numbers.
• Enables individuals with no or very little sight to operate computers independently.
• The drawback is that users must first be proficient at Braille. Also, like screen readers, refreshable Braille displays cannot interpret images or graphs.

3. Screen Magnifiers

• Software used by individuals with low vision.
• Magnifies a portion of the screen for easier viewing.
• Users can control features (i.e. text & background colours) to enhance readability.
• The major weakness is it reduces the area of the document being viewed, removing surrounding context, which can be confusing and disorienting. It may also distort text depending on magnification.

4. Voice Recognition Applications

• Used primarily by individuals with limited or no hand function, or with learning disabilities.
• It enables user to input using voice for data entry and limited software commands.

Glenda Watson Hyatt