  Partial subtle mirroring of nonverbal behaviors during conversations (also
known as mimicking or parallel empathy), is essential for rapport building,
which in turn is essential for optimal human-human communication outcomes.
Mirroring has been studied in interactions between robots and humans, and in
interactions between Embodied Conversational Agents (ECAs) and humans. However,
very few studies examine interactions between humans and ECAs that are
integrated with robots, and none of them examine the effect of mirroring
nonverbal behaviors in such interactions. Our research question is whether
integrating an ECA able to mirror its interlocutor's facial expressions and
head movements (continuously or intermittently) with a human-service robot will
improve the user's experience with the support robot that is able to perform
useful mobile manipulative tasks (e.g. at home). Our contribution is the
complex integration of an expressive ECA, able to track its interlocutor's
face, and to mirror his/her facial expressions and head movements in real time,
integrated with a human support robot such that the robot and the agent are
fully aware of each others', and of the users', nonverbals cues. We also
describe a pilot study we conducted towards answering our research question,
which shows promising results for our forthcoming larger user study.
