Expressing Robot Emotion Using Eye Colors, Pupil Sizes, Eye Direction and Head Postures

Abstract At the current time, social robots are poised to enter human society in an unprecedented way. However, robots currently are not adept at communicating emotional states, even if humans to a large extent rely on such communication to regulate interaction. Although facial expressions are difficult for robots to make use of, colored lights are readily available. Currently though, there is no consensus on how to best represent emotions using colors in robots. In this paper, we study how humans perceive the humanoid robot, Epi, when displaying different eye colors, eye color intensity, pupil sizes, head postures in combination with eye directions. Two online experiments were conducted where subjects were presented with pictures of the robot and asked how they perceived it in relation to six different emotions (anger, fear, surprise, disgust, sadness and enjoyment). In experiment 1, we looked at how eye color and light intensity correlates to the different emotions. In experiment 2, we focus on how pupil size, head posture and eye direction affect how the robot is perceived. Results indicate that red is strongly associated with anger, and that people rate Epi as expressing disgust and sadness more when light intensity dims.