Measuring the adaptability of universal accessible systems

Adaptability is a concept to improve access to content and navigation for individual users of information systems in various settings of interaction. Following the usability-engineering tradition to provide operational definitions of principles, and subsequently to develop techniques for evaluation based on these definitions, we revisited adaptability concepts and designed a structured technique (Accessibility through Adaptability, ActA) for checking user interfaces designed to be accessible for a variety of users. ActA enables the measurement in terms of a system's capability to provide accurate interaction features for individual users and their (situative) needs. In the paper we review the multiple dimensions of adaptability and detail the ActA technique. We also exemplify the application of the technique discussing a case study that has been performed within an European R&D-project. The benefits of this approach for evaluation result from the integration of different views on the interface, since the evaluation procedure involves both users, and developers. This way, the technique bridges the gap between developers and users, since user interfaces might be co-constructed based on the results of an evaluation.