Requirements of non-verbal communication in believable synthetic agents

Realism for synthetic characters, both in computer games and conversational agent mediated applications, requires both visual and behavioural fidelity. One significant area of synthetic character behaviour, that has to date received little attention, is non-verbal communication. In identifying the scope and participants of non-verbal communication in computer games we first review the range of spatial and task scenarios that are relevant. We then select four principal categories of non-verbal behaviour: gesture; gaze; proxemics; self-adaptors; and both summarise their role in communication and propose their incorporation in the design of non-player characters. In conclusion we review the question of how to capture the non-verbal behaviour of players or provide them with interaction techniques that might facilitate non-verbal communication with players and non-player characters alike.