In human-computer interaction,
computer accessibility (also known as
Accessible computing) refers to the accessibility a computer system to all people, regardless of disability or age-related limitations. It is largely a software concern; when hardware, or a combination of hardware and software, is used to customize a computer for a disabled person this is known as Assistive Technology.
There are several types of disabilities that impact computer use. These include:
*Cognitive disabilities, such as dyslexia, ADHD or autism.
*Complete or partial blindness, including color blindness.
*Deaf or hard of hearing.
*Motor or dexterity disability such as paralysis, cerebral palsy, or carpal tunnel syndrome.
*Impairments due to aging.
In Free software contexts, accessibility is often abbreviated to
a11y, where the number 11 refers to the number of letters omitted. This parallels the abbreviations of
internationalization and
localization as i18n and l10n respectively.
Considerations for specific disabilities
Cognitive disabilities and illiteracy
The biggest challenge in computer accessibility is to make resources accessible to people with cognitive disabilities - particularly those with poor communication skills - and those without reading skills.
Visual disabilities
Another significant challenge in computer accessibility is to make software usable for people with visual impairment since computers are largely visual devices. For people with poor vision, it is helpful to use large fonts, high-contrast icons etc. supplemented with auditory feedback and screen magnifying software. In the case of blindness, text to speech (screen reader) software is essential.
About 8% of people, mostly males, suffer from some form of colour-blindness. In a well-designed user interface, colour should not be the only way of distinguishing between different pieces of information. However, the only colours that matter are colours that people with a deficiency might confuse, which generally means red and green and blue and green.
An example in Web accessibility is a set of guidelines
http://www.learningdisabilities.org.uk/page.cfm?pagecode=ISSIWD and two accessible
http://www.learningdisabilities.org.uk/page.cfm?pagecode=ISSIWDAS web portals designed for people developing reading skills are peepo.com
http://www.peepo.com — try typing a letter with your keyboard for more — and peepo.co.uk
http://www.peepo.co.uk with enhanced graphics, unique style controls and improved interactivity (requires SVG supported browser).
Motor disabilities
Some people may not be able to use a conventional input device, such as the mouse or the keyboard. Therefore it is important for software functions to be accessible using both or either device; ideally, software uses a generic API that permits the use even of highly specialized devices unheard of at the time of software development. Keyboard shortcuts and mouse gestures are ways to achieve this. More specialized solutions like on-screen keyboards and alternate input devices like switches, joysticks and trackballs are also available.
The astrophysicist Stephen Hawking is a famous example of a person suffering from motor disability. He uses a switch, combined with special software, that allows him to control his wheelchair-mounted computer using his remaining small movement ability. This performs as a normal computer, allowing him to research and produce his written work, and as a Voice Output Communication Aid (VOCA) and environmental control unit.
Aural disability
While sound user interfaces have a secondary role in common desktop computing, usually limited to system sounds as feedback, software producers take into account people who can't hear, either for personal disability, noisy environments, silence requirements or lack of sound hardware.
The system sounds like beeps can be substituted or supplemented with flashing parts of the screen or text (akin to closed captions).
Web accessibility
Enabling access to Web content for all users is the concern of the Web accessibility movement. Websites can be designed to be more accessible by their conformance to certain design principles.
Screen readers are of only limited use when reading text from websites; this can be due to the differences between spoken and written language and the complexity of text, but it is mainly due to poor page design practices. The tendency to indicate semantic meaning using methods that are purely presentational (e.g. larger or smaller font sizes, using different font colors, or images or multimedia to provide information) restricts meaningful access to some users. Therefore designing sites in accordance with Web accessibility principles helps enable meaningful access for all users.
For example, web designers can ensure that navigation and content is as plain and simple as appropriate and long texts should provide summaries. Texts can be supplemented by symbols, illustrations, comics and photographs .
See also
*
Modding* Assistive Technology
* Web accessibility
* Section 508 Amendment to the Rehabilitation Act of 1973
Live Forums
*
Chat with experts on internet accessibility
External links
*
The annual ERCIM Workshop on 'User Interfaces for All' emphasising accessibility
*
Better Living Through Technology - contains guides on accessibility options and information about specialist assistive hardware and software
*
HP Accessibility *
Illinois Accessible Web Publishing Wizard for Microsoft Office
Accessibility features of Operating Systems
*
Microsoft Accessibility *
Apple Accessibility *
The GNOME Accessibility Project *
The KDE Accessibility Project Web browser accessibility features
*
Accessibility in the Opera web browser *
Mozilla Accessibility Project *
Internet Explorer 6 Accessibility Resources Category:Accessibility
Category:Assistive technology
Category:Human-computer interaction
Category:Technical communication
