Assistive Technology – The Bridge Between Computers and Disabled Users
By Ben Tomsky, & Urte Meinhardt, SAP User Experience – 06/07/2005 • updated 01/06/2006 • Original article
Throughout the software development community, a tremendous amount of effort is going into the process of making Websites and software applications compliant with legal regulations. Other aspects of creating accessible software solutions receive less attention. In fact, Section 508 and similar regulations represent only half the story of how disabled individuals access electronic media – assistive technology (AT) forms the crucial link between the disabled user and the computer.
What is Assistive Technology?
There is not only one definition for assistive technology. Numerous different ones result out of the fact that different outcome and various technologies are in focus.
- Section 508 provides the following answer to this question: "Assistive technology is defined as any item, piece of equipment, or system, whether acquired commercially, modified, or customized, that is commonly used to increase, maintain, or improve functional capabilities of individuals with disabilities." Yet, this definition is very broad, potentially including anything from wheelchairs to hearing aids. In the context of Section 508, the term typically refers to tools used by disabled individuals to increase or improve the functionality of information technology.
- The Technology Related Assistance for Persons With Disabilities Act of 1988 defines Assistive Technology as: Any piece of equipment or product system, whether acquired commercially of the shelf, modified or customized, that is used to increase, maintain or improve functional capabilities of individual with disabilities. The definition does not imply that assistive technology must include computers, or that it must be expensive, or that certain medical professionals can only prescribe it. This definition permits assistive technology to only be restricted by our own creativity and imagination.
Assistive technology can be either software- or hardware-based. Hardware solutions can span a broad range of devices, from low-tech items such as mouth sticks or paper stabilizers, to high-tech products such as refreshable Braille displays or eye gaze communication systems. Software solutions can include built-in features such as the accessibility options in Microsoft Windows or stand-alone programs such as speech recognizers and screen readers. The most appropriate type of AT for a disabled individual depends on the nature of the disability.
The following outline of assistive technology, grouped by the nature of a user's disability, represents a sample of the many types of assistive technology that are available.
Assistive Technology for Visual Impairments
Visually impaired individuals include those who are completely blind as well as those who have low vision, those who are colorblind, and those with impaired optical muscle control. Each of these conditions calls for a slightly different assistive technology.
Blind Users
Blind users face the greatest challenge when interacting with graphical user interfaces. Typically, they use software applications known as screen readers that turn the text, events, and elements in applications and Websites to synthesized speech. For example, when a user opens a new window in Microsoft Internet Explorer, a screen reader might say "new browser window."
Special key combinations are used to move around screens in order to direct the screen reader what to read. By listening to this speech, blind users are able to understand a screen's content.
A refreshable Braille display may be used as a supplement or alternative to a screen reader. These devices convert screen text to Braille and display the Braille on a number of cells comprised of independently controlled pins. When editing and reviewing text, refreshable Braille displays can be much better to work with because a blind user can easily reread characters on the same line and check spelling. Screen readers are capable of reading words character by character, but the process of moving backwards in text to review and then moving forwards can be cumbersome. Despite their potential advantages, refreshable Braille displays are less common because of their high cost and because especially in the US the majority of blind individuals do not read Braille. See www.pulsedata.com/products/notetakers/Notetakers_index.asp for an example of refreshable Braille displays.
A Braille embosser transfers computer generated text into embossed Braille output. Braille translation programs convert text scanned-in or generated via standard word processing programs into Braille, which can be printed on the embosser. The result on thick paper are the individual dots that constitute Braille characters. See www.brailler.com/tom.htm for an example.
Users with Low Vision
Users with low vision utilize screen magnifiers, software which enlarges information on the screen by a user-defined factor (e.g., 2x magnification, 3x magnification, etc.). These applications can magnify parts of the screen, the full screen, or provide a magnifying glass view of an area around the cursor or pointer. Because of this enlarging, users with low vision can read onscreen text and interact with screen elements.
Alternative keyboards provide features like larger- or smaller-than-standard keys or keyboards, alternative key configurations for a better usage for users with low vision.
See www.doit.wisc.edu/accessibility/video/screen_magnification.asp for a short video with examples.
Assistive Technology for Mobility Impairments
The term "mobility impairment" refers to any condition that limits one's ability to navigate his or her environment. Some conditions that result in mobility impairments are: brain damage, muscular dystrophy, arthritis, paralysis, and amputation. To accommodate the variety of potential mobility impairments, many different types of AT are available.
Alternative pointing devices allow mobility-impaired individuals to control the mouse pointer via a mechanism other than the mouse. These are typically used when someone lacks the dexterity to manipulate a standard mouse.
Perhaps the most simple of these devices, software exists that converts the keyboard's arrow keys into directional movements for the pointer. Other keys are used to signal a left and right mouse click. For users with very limited motion with their hands, a standard computer joystick may be used in combination with special software that converts the joystick's motion to directional control of the pointer.
Technologically complex solutions exist for individuals with severe impairments, entirely unable to manipulate the mouse and/or use a standard keyboard. For example, the HeadMouse wireless pointing device (see orin.com/access/headmouse/index.htm) converts the movements of a user's head into corresponding movements of the mouse pointer by optically tracking the motion of a single point on the user's head. A standard keyboard may be completely replaced by using this system in conjunction with software that produces an on-screen keyboard.
In addition to this combination of two technologies, other alternatives to conventional keyboards exist. For users with somewhat compromised manual dexterity, keyboards with extra-large keys may be used. See www.fentek-ind.com/bigkey.htm for examples.
As yet another option, mobility impaired individuals may utilize speech recognition applications. This software can be used to both control applications via speech commands and as a means to dictate text, with the speech converted to text in real-time. See www.lhsl.com/products for examples.
Assistive Technology for Hearing Impairments
Hearing impairments affect individuals over a range of severity, including the inability to hear certain types of sounds, the inability to hear any sound, and difficulty distinguishing words. Because computers rarely convey information with sound alone, hearing impaired individuals have encountered few accessibility problems-at least until the arrival of multimedia. Yet, some solutions are emerging.
Computer prompts such as spoken messages and beeps can be misunderstood or go unnoticed by hearing impaired individuals. This problem is solved through the use of tools that produce a visual warning when the system plays a sound and/or tools that display captions in place of a spoken message. Light signaler alerts the computer user with light signals. This is useful when a computer user can not hear computer sounds. As an example, a light can flash alerting the user when a new e-mail message has arrived or a computer command has completed.
TTY/TDD conversion modems are connected between computers and telephones to allow an individual to type a message on a computer and send it to a TTY/TDD telephone or other Baudot equipped device. Voice recognition products convert what is being spoken to text or sign language. Some products provide an option to convert a visual image to text or sign language.
Assistive Technology for Cognitive Impairments
Given the disparate nature of the many learning and cognitive impairments, a variety of assistive technologies is employed, often overlapping with those used by other groups of disabled individuals. For example, cerebral palsy is a cognitive condition that potentially causes any combination of the following: visual impairments, mobility impairments, and hearing impairments. Thus, individuals affected by cerebral palsy may utilize any number of assistive technologies that are also used by individuals with other impairments.
However, some assistive technologies are designed specifically for cognitive impairments. Word prediction software is used by dyslexic individuals and those who type very slowly. This software predicts the completion of the word currently being typed and can predict the next word based on word context and frequency. See www.madentec.com/products/comaccess/telepathic/telepathic.html for an example.
Conclusion
As evidenced by the above descriptions, assistive technology services addresses a variety of disabilities in numerous ways. Yet, designers and developers need not concern themselves with the details of each assistive technology. The established guidelines and legislations, such as Section 508 and the Web Accessibility Initiative, provide explicit checkpoints that facilitate the production of Websites that are compatible with multiple types of assistive technology. However, universal guidelines do not provide coding techniques for languages other than HTML. Therefore, when developing applications, an expert in assistive technology should be consulted in order to avoid creating barriers for assistive technology users.
For more information on accessibility standards, see the Design Guild article (Edition 9: Accessibility) In Support of Harmonized Global Accessibility Standards.
For more information on accessibility legislation, see the Design Guild article (Edition 9: Accessibility) Accessibility Legislation – an Insight.
Further References
Please note that we cannot assure that the links below will work in the future.
- www.webaim.org/techniques/motor/assistive.php
- www.microsoft.com/enable/at/types.aspx
- www.dinf.ne.jp/doc/english/Us_Eu/conf/csun_99/session1017.html
