
3.2 Multimodal signals
As described in Section 2.1.1, backchannels are provided not only
through the visual modality, but also through voice by uttering
paraverbals, words or short sentences (Gardner, 1998; Allwood et
al., 1993). For such a reason to create credible virtual agents, this
type of signals must be taken into account. Bevacqua et al. (2010)
proposed to improve user-agent interaction by introducing multimodal
signals in the backchannels performed by the ECA Greta. Moreover,
they presented a perceptual study with the aim of getting a better
understanding about how multimodal backchannels are interpreted
by users. Like in their previous ...