Evaluation of Artificial Mouths in Social Robots [Online]
IEEE Transactions on Human-Machine Systems

The external aspects of a robot affect how people behave and perceive it
while interacting. In this paper, we study the importance of the mouth
displayed by a social robot and explore how different designs of an
artificial LED-based mouths alter the participants’ judgments of a
robot’s attributes and their attention to the robot’s message. We
evaluated participants’ judgments of a speaking robot under four
conditions: 1) without a mouth; 2) with a static smile; 3) with a
vibrating, wave-shaped mouth; and 4) with a moving, human-like mouth. A
total of 79 participants evaluated their perceptions of an on-video
robot showing one of the four conditions. The results show that the
presence of a mouth, as well as its design, alters the perception of the
robot. In particular, the presence of a mouth makes the robot to be
perceived more lifelike and less sad. The human-like mouth was the one
participants liked the most and, along with the smile, they were the
friendliest ones. On the contrary, participants rated the mouthless
robot and the one with the wave-like mouth as the most dangerous ones.