While user-centered design (UCD) is a commonly used process for designing mainstream hardware, software, and web interfaces; design for accessibility is relatively uncommon in education and practice. As a result, the scope of users and the situations in which they operate products is not as inclusive as it could be. Designing for accessibility does not require a whole new process. Accessible design techniques fit well into established UCD processes for designing a range of products, from a handheld device, to office software, to a government web site. By integrating accessibility into the design process, designers can efficiently create products that work effectively for more people in more situations.
Accessibility is the ability for a person to be able use a product when they are experiencing functional limitations. Accessible products can be used by more people, effectively, in more situations. User-centered design (UCD) is a user interface (UI) design process that considers usability goals, user characteristics, environment, tasks, and workflow in the design of an interface.
While UCD is an established and commonly used process for designing mainstream hardware, software, and web interfaces, design for accessibility is relatively uncommon in education and practice. As a result, the scope of users and the situations in which they operate products is not as inclusive as it could be if the needs of people with disabilities were considered in design. For example, accessibility considerations can be incorporated in elements as:
Designing for accessibility does not require a whole new process. Accessible design techniques fit well into established UCD processes for designing a range of products, from a handheld device, to office software, to a government web site.
Accessibility is not just about disabilities. Functional limitations can be due to disabilities, or due to constraints imposed by the situation or environment. The issues of and solutions to accessible design are essentially the same whether you are specifically concerned about designing a mobile Internet appliance with input and output limitations, designing a public kiosk to be accessible to people with disabilities, or designing a web application targeted to older users. Accessible products can be used hands-free, eyes-free, or ears-free - requirements of many mobile products - and by people who are in noisy or dark environments. Designing products that do not rely on the ability of the user to be able to read printed text - a design requirement for blind access - increases usability by people with low literacy or no literacy.
Older users with diminishing hearing, sight, physical abilities, and cognitive abilities are an important market for many organizations. Various situational constraints from the environment, circumstance, or device - such as eyes-free operation of navigation and cellular communications systems in vehicle - are another area of increasing activity. It is important to design for limiting conditions from both an inclusive design standpoint, and a business standpoint.
Recent governmental regulations have compelled companies and organizations to make products accessible to people with disabilities. For example, in the United States:
Accessibility considerations come into play at each step in the process, including the analysis phase, the design phase, and throughout evaluation. At the project level, consider accessibility in planning and staffing projects, understanding business objectives, and defining product parameters. Accessibility is most efficiently and effectively implemented when included from day one of a project. Considering accessibility early in the project will increase the design impact and decrease the resource impact.
Include accessibility considerations in developing a vision, usability goals, and user performance requirements; conducting field studies; and developing user profiles and scenarios. Early in the analysis phase, designers can look for successful examples of accessibility solutions in:
Years of research and practice have culminated in guidelines developed in cooperation with industry, people with disabilities, and academia. These guidelines cover hardware, software, and web pages, at various levels of specificity. Each of the regulations has associated guidelines; for example, the Electronic and Information Technology Accessibility Standards (EITAS) under Section 508. Additional resources, such as the techniques related to the Web Content Authoring Guidelines  from the World Wide Web Consortium (W3C) Web Accessibility Initiative (WAI), can help designers address regulations and design more accessible products.
Understanding all of the disabilities issues, and even each specific design guideline, can be a daunting task. Every designer need not fully understand, for example, all categories of blindness including pathologies, degrees, causes, and mental models of people who are blind. Rather, it is most important that designers understand basic access issues faced by consumers with functional limitations. For example, it is important for designers to understand what it means to use a product without relying on vision. It is also important to get input from consumers with functional limitations at key points in the design process. Adapting the usual design process into an accessible design process can be made simpler by adopting the functional limitation perspective.
Several documents provide examples of guidelines that incorporate a functional limitation perspective, including Section 508  EITAS subsection 1194.31 Functional performance criteria (Figure 1) and the Telecommunications Act (Figure 2).
The Telecommunications Act Accessibility Guidelines specifically direct manufacturers to evaluate accessibility:
"Manufacturers shall evaluate the accessibility, usability, and compatibility of telecommunications equipment and customer premises equipment and shall incorporate such evaluation throughout product design, development, and fabrication, as early and consistently as possible. Manufacturers shall identify barriers to accessibility and usability as part of such a product design and development process." (1193.B )
Evaluating for accessibility - that is, assessing a product's usability from the perspective of users with functional limitations or situations that create functional limitations - requires the same basic evaluation methods and techniques commonly used in UCD, with modifications. For example, design walkthroughs can be conducted with scenarios where the user is using a screen reader or not using a mouse. Heuristic evaluations can be conducted using functional performance criteria, such as that provided in Section 508 EITAS 1194.31 Functional performance criteria (Figure 1) and the Telecommunications Act (Figure 2).
Screening techniques for accessibility and usability are simple, quick, and inexpensive simulation activities that can be used by usability evaluators to gauge the usability of a product prior to testing with people with disabilities. Screening tests can be used early in the design process by the design staff themselves, and later with initial usability test participants. A set of screening techniques can be used to evaluate several functional limitations, such as:
Standard usability testing practice can also be used to evaluate accessibility, with modifications.
In usability test planning, consider accessibility in the following:
In usability test recruiting, consider accessibility in the following:
In preparing for usability tests, consider accessibility in the following:
In conducting usability tests, consider accessibility in the following:
For many designers, accessibility is a new and exciting opportunity to positively impact product design, their organization, and society as a whole. Designers can contribute to the growing body of knowledge as accessibility continues to progress in mainstream product design. By integrating accessibility into the design process, designers can efficiently create products that work effectively for more people in more situations.
Partially funded by the National Institute on Disability and Rehabilitation Research of the Department of Education under Grants #H133E980008 and #H133E990006. The opinions contained in this publication are those of the grantee and do not necessarily reflect those of the Department of Education.