User control in adaptive user interfaces for accessibility

Adaptive user interfaces offer great potential for improving the accessibility of interactive systems. At the same time, adaptations can cause usability problems, including disorientation and the feeling of losing control. Adaptations are therefore often discussed in terms of costs and benefits for the users. However, design strategies to overcome the drawbacks of adaptations have received little attention in the literature. We have designed different adaptation patterns to increase the transparency and controllability of run time adaptations in our MyUI system. This paper presents an experimental user study to investigate the effectiveness and acceptability of the proposed patterns in different cost-benefit situations and for different users. The patterns turn out to increase the transparency and controllability of adaptations during the interaction. They help users to optimize the subjective utility of the system's adaptation behavior. Moreover, the results suggest that preference and acceptance of the different patterns depend on the cost-benefit condition.