Edited by Dr. Mark Magennis, Director, Centre for Inclusive Technology (CFIT), NCBI, Dublin, IrelandAccessibility principles
There are three aspects to accessibility: a user must be able to perceive, understand, and operate every control, instruction or output. This section discusses how the accessibility of ICT products can be enhanced, using simple means like maximising the accessibility of the basic components, allowing for a range of interaction methods, giving different kinds of output, and ensuring compatibility with different assistive technologies. Increasing accessibility leads to a greater usability towards all users, and so is a standard to be worked towards.
For full accessibility, all users must be able to do three things for every control, instruction or output:
• Perceive it
• Understand it
• Operate it
Perceiving a control, instruction or output means both being aware of its existence and being able to access its information.
For example, a deaf person may be unaware of the existence of an audible alarm signal whereas a blind person will be unaware of a visual signal. A person with low vision may be aware of the text on an ATM display but have such difficulty reading it that they cannot access the information it provides.
Understanding means knowing what it means and how to use it.
A person with a learning disability may be unable to follow complicated or poorly written instructions on an ATM. They may find it difficult to learn where to find things on an inconsistent website.
Operating means being able to reach it and physically interact with it in the required way, which might mean pressing, moving, twisting or pulling.
A wheelchair user may be unable to reach the card slot on an ATM. Someone with a hand tremor may find it difficult to accurately press small buttons on an alarm keypad in order to enter their code.
How can ICT products be made accessible?
An ICT product is accessible to a person with a disability if they can use it either as it is, with minor adjustment or configuration, or in conjunction with some assistive technology.
It may be difficult or even impossible to design a specific product in a way that all people can use it fully as it is, without requiring any adjustment or add-ons. However, most products can be made accessible to most users by maximising the basic accessibility, allowing user configuration, allowing a range of interaction methods, providing outputs in multiple forms and ensuring compatibility with assistive technologies.
Maximizing the accessibility of basic components
The basic accessibility of a product can be maximized by simple design choices such as using large well-spaced buttons instead of small crowded ones, giving clear instructions instead of long-winded jargon and using good contrasts for text and graphics. There is nothing special about this. It is just good design practice.
Allowing users to configure the product to suit them
Giving users the ability to configure a product to suit them is often a good way of providing for a range of different needs. For example, ATMs, websites, mobile phones and PC applications can provide a choice of different text sizes and colour schemes to suit people with different visual abilities. In an alarm system it may be possible for slow users to increase the amount of time they are allowed to key in their code. Some remote controls have been made with two sides, giving a choice between the full function version or a simpler version with fewer, larger buttons covering only the most essential functions.
Allowing a range of interaction methods
A PC application can be made to accept interaction via the keyboard as well as a mouse, catering for people unable to use a pointing device. Allowing voice commands in addition can open up the product further to include people who have difficulty using any physical interaction method.
(Image above is taken from orangeacid's photostream on Flickr. CC BY 2.0)
For communicating inputs and making choices, a product could also allow a range of different methods. For example, when a list of options is presented in an on-screen menu, users can be allowed to make choices by using the arrow keys and a Select button or alternatively by pressing a digit corresponding to the desired option. The first method may work better for people with some cognitive impairments. The second may be easier for people with some physical disabilities because it requires fewer key presses. Allowing both methods caters for both types of users.
It is never a good idea to rely on only one interaction method because there will always be someone who cannot interact in that way.
Providing outputs in multiple forms
Because some people cannot perceive some forms of output, providing multiple forms caters for more people. For example, using both an audible ‘beep’ and a visible light would make the house alarm accessible to both blind and deaf people. Similarly, a keypad can be made to provide key press feedback as an audible ‘click’, a tactile click and a visual flash.
Many ICTs display textual or graphical information on a screen. This can also be presented as speech for people who cannot see or read written text. For example, an ATM can speak out the instructions, menu choices and responses. A headphone socket can be provided which switches the machine to this non-visual interaction mode when a set of headphones is plugged in. Some touchscreen-based mobile phones and PDAs include software to allow a blind person to locate screen objects such as icons and buttons by tracing their finger around the screen and listening as each object they ‘touch’ is announced in a synthetic voice. Together with text-to-speech functionality, it is possible to make almost all of the device’s functions usable in this way. For people with learning disabilities, it is often useful to augment textual instructions with pictures. For audiovisual content, adding captions (subtitles) and audio description can make all the information available to people who are deaf, hard of hearing or blind.
Ensuring compatibility with assistive technologies
Many people with disabilities interact with other technologies through personal ‘assistive technologies’. These range from simple devices like hearing aids to the complex text-to-speech ‘screen reader’ software used by blind people to operate a PC, use software applications, access websites, etc. For a person with a disability, assistive technology provides a standard intermediary interface with interaction methods and output formats suited to their needs. For a product designer, interfacing with assistive technology removes the need to add those interface capabilities into the product itself. For example, a software application or a website does not need to provide spoken output of text if it can interface with assistive technologies like screen readers which provide text-to-speech capability. As far as possible then, products should be made compatible with these assistive technologies.
Improving overall design through accessibility enhancements
Making something accessible doesn’t mean making it worse for ‘normal’ use. In fact, increased accessibility often results in improved usability for all users. The methods of improving accessibility described above can usually be done without reducing functionality, over-simplifying the product or otherwise making it less suitable for non-disabled users. These approaches to accessibility are all additions – added flexibility, additional modes, more choice. The aim is always to allow access to the equivalent functionality, but in an alternative way. This is the true meaning of accessibility.