A reference framework for continuous interaction

The latest developments in human computer interfaces aim at greater ease of use, and the exploitation of human communication and interaction skills typical of non-computerised environments. This kind of interaction is continuous rather than purely discrete. Continuous in- teraction implies a tighter coupling between system and user, and raises complicated synchronisation issues where real-time requirements and intrinsic variation of human behaviour play an essential role. In this paper, we propose a human centred layered reference model to reduce the design complexity of systems exhibiting continuous inter- action. In the context of the layered model, we discuss the role that formal modelling can play in the design of these systems.