  How human-like do conversational robots need to look to enable long-term
human-robot conversation? One essential aspect of long-term interaction is a
human's ability to adapt to the varying degrees of a conversational partner's
engagement and emotions. Prosodically, this can be achieved through
(dis)entrainment. While speech-synthesis has been a limiting factor for many
years, restrictions in this regard are increasingly mitigated. These
advancements now emphasise the importance of studying the effect of robot
embodiment on human entrainment. In this study, we conducted a between-subjects
online human-robot interaction experiment in an educational use-case scenario
where a tutor was either embodied through a human or a robot face. 43
English-speaking participants took part in the study for whom we analysed the
degree of acoustic-prosodic entrainment to the human or robot face,
respectively. We found that the degree of subjective and objective perception
of anthropomorphism positively correlates with acoustic-prosodic entrainment.
