One idea that is a possible extension to this thesis is the construction of a complete human-computer interface based on behaviour learning. The computer could then predict the state of a user, and simulate a synthetic face or character. This does not only involve face behaviour recognition but also speech recognition and gesture recognition. The model could also be extended to other type of interaction such has human/non human interaction. For instance, interaction between a driver and its vehicle could be study. Such an interaction could be useful for games for instance where the game designer want have a realistic driver. It can also be use for the driving licenses tests to recognize wrong behaviours or even model and synthetise wrong behaviours to teach people what they should not do.