User capability in an adaptive world

General computing devices are becoming increasingly ubiquitous, personal, and mobile; and bring expectations of multimedia delivery with them that are traditionally the domain of desktop computing. Given their small form factors with restricted interaction modalities, optimizing interaction between user and device becomes critical to the usability and accessibility of the device. To this end, we present simple but powerful models of user capability, capacity, and preference that allow for a wholly adaptive and optimized user experience, with the models driving selection and configuration of appropriate interaction modalities, and themselves adapting their settings in order to reflect both changes in the environment, and the history of user behaviour. In order to achieve this, user profiles are no longer collections of purely static values, but may also contain functionally dependent properties that are changeable in response to external events. The models themselves do not perform any adaptation, but aim to drive the adaptation process.