
248 Coverbal Synchrony in Human-Machine Interaction
2.1.3 Facial expressions
The face is an important channel of non-verbal communication. During
interaction, both while speaking and listening, facial expressions
are used to accomplish several fundamental tasks. They can help to
regulate the flow of the conversation (Duncan, 1972), for example by
smiling to the speaker, the listener can encourage her/him to go on in
the conversation (Poggi and Pelachaud, 2000). Facial expressions have
been found to convey one’s opinion about events, people or objects
(Chovil, 1992), through this kind of facial displays, called personal
reactions, a person shows ...