Quality in use for all

Designing an interactive product or service for all possible users requires consideration of more than just physical accessibility. Even if there is sufficient physical accessibility, many systems will still present major barriers to their use, in terms of cognitive accessibility: the functionality, terminology, information structure and interface style frequently confuse the intended user. Usually, the main emphasis in systems design is on building systems that meet specific functional requirements, without a sufficiently detailed understanding of the cognitive and physical capabilities and expectations of the intended users, or a clear view of the context in which the system will be used. The problem is compounded by the difficulty that designers usually have in recognizing shortcomings or limitations in their own design. There are cost-effective procedures for dealing with this problem, which have recently been formalized in ISO 13407: Human-centred design process for interactive systems. User-centred design provides a framework which can potentially make “Design for All” a reality. The goal is to achieve quality in use for all. User-centred design encompasses processes, tools and techniques which can be used to identify and document the complete range of user requirements, including special needs arising from (dis-)abilities, skills, preferences, or any other characteristic of the end user population. The tight design / evaluation loop advocated by user-centred design provides feedback to correct design deficiencies at an early stage while changes are relatively simple to make. Procedures for evaluating quality in use have been developed as part of approaches to usability evaluation, and now need to be extended to encompass procedures for evaluating accessibility. In summary, “Design for All” entails both physical and cognitive accessibility. New hardware and software technologies are required to make it easier to provide physical accessibility. New integrated approaches to system development are required to make it easier to provide cognitive accessibility. Only by combining these activities can “Design for all” be achieved.