A User Trust Model for Automatic Decision-Making in Ubiquitous and Self-Adaptive Environments.

Ubiquitous Environments are able to support users during their daily life by intelligently self-adapting to changed contexts. Examples include home automation systems which can support energy saving by switching off unused devices or public displays which enable users to present and interact with data, but maintain the users' privacy by hiding sensible data if others pass by. However, such proactive adaptations could also cause frustration and thus harm the users' acceptance and trust towards a system if they do not match the users' preferences or are not self-explanatory. In the worst case, wrong or incomprehensible decisions by the system even could make the users abandon the system. To address this concern, we propose a generic trust-based model, called User Trust Model (UTM), which facilitates automatic decision-making in ubiquitous and self-adaptive environments. It is supposed to monitor users' trust in the system and to select context-aware system actions that maintain, restore, or even foster user trust. In this chapter, the construction of the generic model as well as its integration into two case studies will be presented. We will provide a detailed description of how to customise the UTM for the respective scenarios and share results and experiences from various studies conducted with the developed systems.