Attempting to develop accessible software products means to take into account special needs of impaired users. In this regard the following four categories of impairments need to be considered:
- visual impairments,
- hearing impairments,
- physical impairments,
- cognitive and learning impairments.
The principle of equal treatment has originated various international, European, and national standards, laws, and regulations on accessibility. The knowledge of accessibility standards is a great convenience when designing or developing accessible software products. In order to cover all relevant aspects of existing standards, laws, and regulations on accessibility various companies and organizations (like Microsoft, IBM, Apple, and W3C) have compiled suitable guidelines and checklists for a successful development of accessible applications in different technical domains.
Since developing standards as well as writing guidelines and checklists is an ongoing process, designers, developers, and product managers who are preparing to build an accessible software product are recommended to check out for the most recent standards, regulations, guidelines and checklists which are tailored to the particular area they are working in at best.
Developers need to realize that by focusing too much on persons and abilities (as may easily happen when talking about Personas or Target User Groups) the influence of the mobile context may easily be obscured. Looking at abilities, one is easily tempted to state that a typical user will have good eyesight, good hearing and no motoric or cognitive problems. Re-writing this in terms of a specification of context one gets:
- Optimal lighting and the user can easily look at the screen.
- Quiet environment without sound restrictions.
- The user holds the device in the hands (no gloves or similar) and no external vibrations or shaking makes it hard to feel touch feedback.
- The user has nothing else in the hands and can use both two handed and one handed grips. No shaking or vibrations that interfere with the ability to interact.
- The context does not require any attention.
Looking at this list it is clear that an “optimal” situation where all these points are true is far from typical as a mobile usage situation. As was stated earlier in situation induced impairments, non-optimal conditions are common, and design teams need to take such non-optimal conditions into account explicitly.
Further general information can be found in a number of useful existing guidelines.