Computer accessibility

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".^[4][5] 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.^[6]

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.^[7] 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.^[8]

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.^[9][10]

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 software^[11][12] (being standardized as ISO/IEC TR 13066-6^[13]);
• Assistive Technology Service Provider Interface (AT-SPI) on UNIX and Linux (being standardized as ISO/IEC PDTR 13066-4^[14]);
• 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 13066-3:2012^[15]);
• 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.^[16][17]

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, ClickLock^[18] 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.
• ToggleKeys^[19] 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^[20]
• Switch-accessible software (navigable with a switch)
• Hand–eye coordination skills software
• Diagnostic assessment software
• Mind mapping software
• Study skills software
• Symbol-based software^[21]
• Text-to-speech
• Touch typing software

Effects in school

Computer accessibility plays a large role in the classroom. Accessible technology can enable personalized learning for all students.

Effects in the workplace

Computer accessibility plays a large role in the workplace. In the past few years, adults have had their disabilities accommodated by the ability to work from home and by the availability of reliable software. This allows workers to work in a comfortable area while still being able to support themselves. This is allowing thousands of people with disabilities to create and earn jobs for themselves. The inexpensiveness and reliability of computers has facilitated the process.^[46]

Section 508 of the Rehabilitation Act of 1973

Section 508 requires US Federal agencies make their electronic and information technology (EIT) accessible to all disabled employees and members of the public. The US Access Board develops and maintains the Information and Communication Technology (ICT) accessibility standards.^[47] The Access Board issued a final rule that went into effect on January 18, 2018, updating accessibility requirements under Section 508. This final rule requires that all electronic content generated by US Federal agencies must conform to Level A and Level AA success criteria in WCAG 2.0, with four exceptions for non-Web documents: 2.4.1 Bypass Blocks, 2.4.5 Multiple Ways, 3.2.3 Consistent Navigation, and 3.2.4 Consistent Identification.^[48]

EN 301 549

EN 301 549 is a harmonised European standard that specifies accessibility requirements for information and communications technology (ICT) products and services, including websites, mobile applications, software, and hardware. Produced jointly by CEN, CENELEC, and ETSI, the standard incorporates WCAG 2.1 in full (as of version 3.2.1) while extending coverage to areas beyond web content, such as hardware, telecommunications, and biometric systems. EN 301 549 supports both the EU Web Accessibility Directive (2016/2102) and the European Accessibility Act (2019/882), and has been adopted internationally, including in Australia (as AS EN 301 549) and Canada (as CAN/ASC – EN 301 549:2024).

International standards