Introduction to Assistive Technologies

Assistive technology, also called accessibility aids, are added to computers by people who use them to make computers more accessible. Some common aids include the following:

Screen magnifiers help people with low vision. These utilities are like a magnifying glass. People using them are able to control what area of the computer screen they want enlarged, and can move that focus to view different areas of the screen. They are also known as screen enlargers or large print programs.

Screen readers are for people who are blind. These aids make on-screen information available as synthesized speech or a refreshable Braille display. They can only translate text based information. Graphics can be translated if there is alternative text describing the visual images. They are also known as blind access utilities or screen reviewers.

On-screen keyboards are used by people who are unable to use a standard keyboard. An on-screen keyboard lets people select keys using a pointing method such as pointing devices, switches, or Morse-code input systems.

Keyboard enhancement utilities are used by people who have trouble typing and controlling a mouse. They allow the user to perform complicated key sequences serially (e.g. Control-C), control the mouse pointer and buttons from the keyboard, and set the key repeat and acceptance rates. These enhancements are built into the base platform and are known as AccessX on Solaris/Linux, AccessPac on Microsoft Windows, and EasyAccess on the Mac.

Speech recognition programs are primarily used by people with mobility impairments. These utilities enable people to control computers with their voice instead of a mouse or keyboard. They are also known speech recognition programs.

Alternative input devices allow individuals to control their computers through means other than a standard keyboard or pointing device. Examples include smaller or larger keyboards, eye-gaze pointing devices, and sip-and-puff systems controlled by breathing.

The following is a larger list of assistive technologies broken down by the disability type who benefits from them.

Assistive Technologies for Physical Disabilities and RSI

Assistive Technology

Function Provided

Alternate Pointing Device

Gives users with limited or no arm and hand fine motor control the ability to control mouse movements and functions. Examples include foot operated mice, head-mounted pointing devices and eye-tracking systems.

Screen Keyboard

On-screen keyboard which provides the keys and functions of a physical keyboard. On-screen keyboards are typically used in conjunction with alternate pointing devices.

Predictive Dictionary

Predictive dictionaries speed typing by predicting words as the user types them, and offering those words in a list for the user to choose.

Speech Recognition

Allows the user with limited or no arm and hand fine motor control to input text and/or control the user interface via speech.

Keyboard Enhancements


Function Provided


Provides looking or latching of modifier keys (e.g., Shift, Control) so that they can be used without simultaneously pressing the keys. This allows single finger operation of multiple key combinations.


An alternative to the mouse which provides keyboard control of cursor movement and mouse button functions.


Delays the onset of key repeat, allowing users with limited coordination time to release keys.


Requires a key to be held down for a set period before keypress acceptance. This prevents users with limited coordination from accidentally pressing keys.


Requires a delay between keystrokes before accepting the next keypress so users with tremors can prevent the system from accepting inadvertent keypresses.


Indicates locking key state with a tone when pressed, e.g., Caps Lock.

Assistive Technologies for Low Vision and Blind Users

Assistive Technology

Function Provided

Screen Reader

Allows users to navigate through windows, menus, and controls while receiving text and limited graphics information through speech output or braille display.

Braille Display

Provides line by line braille display of on-screen text using a series of pins to form braille symbols that are constantly updated as the user navigates through the interface.

Text to Speech (TTS)

Translates electronic text into speech via a speech synthesizer.


Provides magnification of a portion or all of a screen, including graphics and windows as well as text. Allows users to track position of the input focus.

Assistive Technologies for Hearing Disabilities

Assistive Technology

Function Provided

Telecommunications Device for the Deaf (TDD)

Provides a means for users to communicate over telephone lines using text terminals.

Closed Captioning

Provides text translation of spoken material on video media. Important computer applications include distance learning, CD-ROM, video teleconferencing, and other forms of interactive video.


Proposed standard would provide visual translation of sound information. Non-speech audio such as system beeps would be presented via screen flashing or similar methods. Video and still images would be described through closed captions or related technologies. This capability would be provided by the system infrastructure.

Accessibility/IntroATs (last edited 2015-08-10 20:54:43 by Richard Marston)