Computer accessibility refers to the accessibility of a computer system to all people, regardless of disability type, English literacy or digital fluency. The term accessibility is most often used in reference to specialized hardware or software, or a combination of both, designed to enable the use of a computer by a person with a disability or impairment.
Accessibility is often abbreviated as the numeronym a11y, where the number 11 refers to the number of letters omitted. Evolving blog. This parallels the abbreviations of internationalization and localization as i18n and l10n, respectively. Moreover, a11y is also listed on the USPTO Supplemental Register under Accessibility Now, Inc.
Accessibility features
Accessibility features are meant to make the use of technology less challenging for those with disabilities. Common accessibility features include text-to-speech, closed-captioning, and keyboard shortcuts. More specific technologies that need additional hardware are referred to as assistive technology.
There are many disabilities or impairments that can be a barrier to effective computer use. Some of these impairments, which can be acquired from disease, trauma, or congenital disorders, include: Cognitive impairments (head injury, autism, developmental disabilities) and learning disabilities, (such as dyslexia, dyscalculia, or ADHD). Visual impairment, such as low-vision, complete or partial blindness, and color blindness. Hearing-related disabilities (deafness), including deafness, being hard of hearing, and hyperacusis. Motor or dexterity impairment such as paralysis, cerebral palsy, dyspraxia, carpal tunnel syndrome, and repetitive strain injury.
A topic closely linked to computer accessibility is web accessibility. Similar to computer accessibility, web accessibility is the practice of making the use of the World Wide Web easier to use for individuals with disabilities.
Accessibility options for specific impairments
Cognitive impairments and illiteracy The biggest challenge in computer accessibility is to make resources accessible to people with cognitive disabilities—particularly those with poor communication and reading skills. For example, people with learning disabilities may rely on proprietary symbols and identify particular products via the product's symbols or icons. Unfortunately, copyright laws can limit icon or symbol release to web-based programs and websites by owners who are unwilling to release them to the public.
In these situations, an alternative approach for users who want to access public computer-based terminals in libraries, ATMs, and information kiosks is for the user to present a token to the computer terminal – such as a smart card – that has configuration information to adjust the computer speed, text size, etc. to their particular needs.
This concept is encompassed by the CEN standard "Identification card systems – Human-machine interface".CEN: Personal identification, electronic signature and cards and their related systems and operations – Structure . This development of this standard has been supported in Europe by SNAPI and has been successfully incorporated into the Local Authority Smartcards Standards e-Organisation (LASSeO) specifications.LASSeO: . August 2011.
Visual impairment Since computer interfaces often require visual input and provide visual feedback, another significant challenge in computer accessibility involves making software usable by people with visual impairments.
For people with mild to medium vision impairment, things like large fonts, high DPI displays, high-contrast themes and icons combined with auditory feedback and screen magnifying software are very useful. In the case of severe vision impairment such as blindness, screen reader software that provides feedback via text to speech or a refreshable braille display is a necessary accommodation for interaction with a computer.
About 8% of men and about 0.4% of women have some form of color-blindness.Chan X, Goh S, Tan N (2014). "Subjects with colour vision deficiency in the community: what do primary care physicians need to know?". Asia Pacific Family Medicine. 13 (1): 10. DOI:10.1186/s12930-014-0010-3. The main color combinations that might be confused by people with visual deficiency include red/green and blue/yellow. However, in a well-designed user interface, color isn't the primary way to distinguish between different pieces of information.
Motor and dexterity impairments
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 devices. Ideally, the software will use a generic input API that permits the use even of highly specialized devices unheard of at the time of software's initial development. Keyboard shortcuts and mouse gestures are ways to achieve this access, as are more specialized solutions, including on-screen software keyboards and alternate input devices (switches, joysticks and trackballs). Users may enable a bounce key feature, allowing the keyboard to ignore repeated presses of the same key. Speech recognition technology is also a compelling and suitable alternative to conventional keyboard and mouse input as it simply requires a commonly available audio headset.
UI design can also improve accessibility for users with motor impairments. For example, barrier pointing design allows commonly used functions to require less accuracy to select.
The astrophysicist Stephen Hawking is an example of someone with severe motor and physical limitations who used assistive technology to support activities of daily living. He used a switch, combined with special software, that allowed him to control his wheelchair-mounted computer using his limited and small movement ability. This personalized system allowed him to remain mobile, do research, and produce his written work. Prof. Hawking also used augmentative and alternative communication technology to speak and an environmental control device to access equipment independently.
A small amount of modern research indicates that utilizing a standard computer mouse device improves fine-motor skills.
Hearing impairment While sound user interfaces have a secondary role in common desktop computing, these interfaces are usually limited to using sound effects as feedback. Some software producers take into account people who cannot hear due to hearing impairments, silence requirements, or lack of sound-producing software. The system sounds like beeps can be substituted or supplemented with visual notifications and captioned text (akin to closed captioning). Closed captions are a very popular means of relaying information for the Deaf and hearing-impaired communities. Modern computer animation also allows for translation of content into sign language by means of sign language avatars, such as SiMAX.
Types of software accessibility
Accessibility application programming interfaces Software APIs (application programming interfaces) exist to allow assistive technology products such as screen readers and screen magnifiers to work with mainstream software. The current or past APIs include: Java Accessibility and the Java Access Bridge for Java softwareOracle: Java AccessibilityOracle: Java SE Desktop Accessibility (page containing a link to the Java Access Bridge). (being standardized as ISO/IEC TR 13066-6ISO: ISO/IEC PRF TR 13066-6: Information technology – Interoperability with Assistive Technology (AT) – Part 6: Java accessibility application programming interface (API).); Assistive Technology Service Provider Interface (AT-SPI) on UNIX and Linux (being standardized as ISO/IEC PDTR 13066-4ISO: ISO/IEC PDTR 13066-4: Information Technology – Interoperability with Assistive Technology (AT) – Part 4: Linux/UNIX graphical environments accessibility API.); Microsoft Active Accessibility (MSAA) on Microsoft Windows; IAccessible2 on Microsoft Windows, a competitor of Microsoft UI Automation also replacing MSAA by Free Standards Group (standardized as ISO/IEC 13066-3:2012ISO: ISO/IEC TR 13066-3:2012: Information technology – Interoperability with assistive technology (AT) – Part 3: IAccessible2 accessibility application programming interface (API).); Mac OS X Accessibility; Microsoft UI Automation on Microsoft Windows, replacing MSAA.
Some of these APIs are being standardized in the ISO/IEC 13066 series of standards.Richard Hodgkinson: 7th Report on International ICT Accessibility Standards Proposed, Being Developed and Recently Published . 3 October 2008.Richard Hodgkinson: 10th Report on International ICT Accessibility Standards Proposed, Being Developed and Recently Published . 26 June 2009.
Accessibility features in mainstream software Accessibility software can also make input devices easier to access at the user level. These include: Keyboard shortcuts and MouseKeys allow the user to substitute keyboarding for mouse actions. Macro recorders can greatly extend the range and sophistication of keyboard shortcuts. Sticky keys allows characters or commands to be typed without having to hold down a modifier key (Shift, Ctrl, or Alt) while pressing a second key. Similarly, ClickLockMicrosoft: Using ClickLock is a Microsoft Windows feature that remembers a mouse button is down so that items can be highlighted or dragged without holding the mouse button down while scrolling. Customization of mouse or mouse alternatives' responsiveness to movement, double-clicking, and so forth. ToggleKeysMicrosoft: To turn on ToggleKeys. Windows XP Professional Product Documentation. is a feature of Microsoft Windows 95 onwards. A high sound is heard when the caps lock, scroll lock, or number lock key is switched on. A low sound is heard when any of those keys is switched off. Customization of pointer appearance, such as size, color, and shape. Predictive text Spell checkers and grammar checkers
Support for learning disabilities Other approaches may be particularly relevant to users with a learning disability. These include: Cause and effect software Switch-accessible software (navigable with a switch) Hand–eye coordination skills software Diagnostic assessment software Mind mapping software Study skills software Symbol-based software Text-to-speech Touch typing software
Open Accessibility Framework
The Open Accessibility Framework (OAF)AEGIS Consortium: AEGIS OAF and high-level architecture. Accessed 2013-01-17. provides an outline of the steps that must be in place in order for any computing platform to be considered accessible. These steps are analogous to those necessary to make a physical or built environment accessible. The OAF divides the required steps into two categories: creation and use.
The "creation" steps describe the precursors and building blocks required for technology developers to create accessible applications and products. They are as follows: Define what "accessible" means for the identified use of the platform. It must be clear what is meant by "accessible" as this will differ according to the modality and capabilities of each platform. Accessibility features may include tabbing navigation, theming, and an accessibility API. Provide accessible stock user interface elements. Pre-built "stock" user interface elements, used by application developers and authoring tools, must be implemented to make use of the accessibility features of a platform. Provide authoring tools that support accessibility. Application developers and content authors should be encouraged to implement tools that will improve the accessibility features of a platform. Using these tools can support accessible stock user interface elements, prompt for information required to properly implement an accessibility API, and identify accessibility evaluation and repair tools.