Users with disabilities

The flexibility of desktop and web software makes it possible for designers to provide special services to users who have disabilities (Edwards, 1995; Vander- heiden, 2000; Paciello, 2000; Stephanidis, 2001; Thatcher et al., 2003). In the United States, the 1998 Amendment to Section 508 of the Rehabilitation Act requires Federal agencies to ensure access to information technology, including computers and web sites, by employees and the public (http//:www.access- board.gov /508.htm). The Access Board spells out the implications for vision- impaired, hearing-impaired, and mobility-impaired users, such as keyboard or mouse alternatives, color coding, font-size settings, contrast settings, textual alternatives to images, and web features such as frames, links, and plug-ins.

Screen magnification to enlarge portions of a display or text conversion to Braille or voice output can be done with hardware and software supplied by many vendors (Blenkhorn et al., 2003). Text-to-speech conversion can help blind users to receive electronic mail or to read text files, and speech-recognition devices permit voice-controlled operation of some software. Graphical user inter- faces were a setback for vision-impaired users, but technology innovations from commercial tools such as Freedom Scientific's JAWS, GW Micro's Window-Eyes, or Dolphin's HAL screen readers facilitate conversion of spatial information into spoken text (Poll and Waterham, 1995; Thatcher, 1994; Mynatt and Weber, 1994). Similarly IBM's Home Page Reader and Conversa's web browser enable access to web information and services. Speech generation and auditory interfaces are also appreciated by sighted users under difficult conditions, such as when driving an automobile, riding a bicycle, or working in bright sunshine.

Users with hearing impairments generally can use computers with only simple changes (conversion of tones to visual signals is often easy to accomplish) and can benefit from office environments that make heavy use of electronic mail and fac- simile transmission (FAX). Telecommunications devices for the deaf (TOO or TTY) enable telephone access to information (such as train or airplane schedules) and services (federal agencies and many companies offer TOO or TTY access). Special input devices for users with physical disabilities will depend on the user's specific impairment; numerous assistive devices are available. Speech recognition, eye- gaze control, head-mounted optical mice, and many other innovative devices (even the telephone) were pioneered for the needs of disabled users (see Chapter 9).

Designers can benefit by planning early to accommodate users who have dis- abilities, since at this point substantial improvements can be made at low or no cost. For example, moving the on/ off switch to the front of a computer adds a minimal charge, if any, to the cost of manufacturing, but it improves ease of use for all users, and especially for the mobility-impaired. Other examples are the addition of closed captions to television programs for deaf viewers, which can be useful for hearing viewers as well, and the use of ALT tags to describe web graphics for blind users, which improves search capabilities for all users.

The motivation to accommodate users who have visual, hearing, and motor disabilities has increased since the enactment of U.s. Public Laws 99-506 and 100-542, which require U.S. government agencies to establish accessible infor- mation environments for employees and citizens. Any company wishing to sell products to the U.s. government should adhere to these requirements. Further information about accommodation in workplaces, schools, and the home is available from many sources:

• Private foundations (e.g., the American Foundation for the Blind and the National Federation of the Blind)

• Associations (e.g., the Alexander Graham Bell Association for the Deaf, the National Association for the Deaf, and the Blinded Veterans Association)

• Government agencies (e.g., the National Library Service for the Blind and Physically Handicapped of the Library of Congress and the Center for Tech- nology in Human Disabilities at the Maryland Rehabilitation Center)

• University groups (e.g., the Trace Research and Development Center on Communications and the Control and Computer Access for Handicapped Individuals at the University of Wisconsin)

• Manufacturers (e.g., Apple, IBM, Microsoft, and Sun Microsystems)

Learning-disabled children, including dyslexics, account for at least two per- cent of the school-age population in the United States. Their education can be positively influenced by design of special courseware with limits on lengthy tex- tual instructions, confusing graphics, extensive typing, and difficult presenta- tion formats (Neuman, 1991). Based on observations of 62 students using 26 packages over 5.5 months, Neuman's advice to designers of courseware for learning-disabled students is applicable to all users:

• Present procedures, directions, and verbal content at levels and in formats that make them accessible even to poor readers.

• Ensure that response requirements do not allow students to complete pro- grams without engaging with target concepts.

• Design feedback sequences that explain the reasons for students' errors and that lead students through the processes necessary for responding correctly. • Incorporate reinforcement techniques that capitalize on students' sophistica-

tion with out-of-school electronic materials.

The potential for benefit to people with disabilities is one of the gifts of com- puting; it brings dividends in the increased capacity for gainful employment, social participation, and community contribution. In addition, many users are temporarily disabled: they can forget their glasses, be unable to read while dri- ving, or struggle to hear in a noisy environment. The University of Wisconsin TRACE Center and the United Nations Enable web sites provide guidelines and resources for designers who are addressing universal usability.