  Visual appearance is an important aspect influencing the perception and
consequent acceptance of Embodied Conversational Agents (ECA). To this end, the
Uncanny Valley theory contradicts the common assumption that increased
humanization of characters leads to better acceptance. Rather, it shows that
anthropomorphic behavior may trigger feelings of eeriness and rejection in
people. The work presented in this paper explores whether four different
autonomous ECAs, specifically build for a European research project, are
affected by this effect, and how they compare to two slightly more
realistically looking human-controlled, i.e. face-tracked, ECAs with respect to
perceived humanness, eeriness, and attractiveness. Short videos of the ECAs in
combination with a validated questionnaire were used to investigate potential
differences. Results support existing theories highlighting that increased
perceived humanness correlates with increased perceived eeriness. Furthermore,
it was found, that neither the gender of survey participants, their age, nor
the sex of the ECA influences this effect, and that female ECAs are perceived
to be significantly more attractive than their male counterparts.
