Arousal and Valence in Robot's Emotional Expression of Breathing and Heartbeat

Abstract

In our past study, we have aimed at emotional expressions of a robot using artificial physiological phenomena, such as breathing and heartbeat, and we demonstrated that both the robot's respiratory rate and heart rate could express the arousal. On the other hand, in previous works, it was not clear whether these physiological phenomena affected the valence (positive -- negative) level of the robot's emotion. In this paper, we also examined other physiological aspects of breathing and heartbeat, specifically the inspiration / expiration ratio and heartbeat variability. Using a robot that was designed based on actual animal respiration and heartbeat mechanisms, we verified whether these physiological changes affect emotional valence in the robot's internal state. The results showed that the robot's emotional valence changed with the interaction of the respiration rate and inspiration / expiration ratio, suggesting the possibility of measuring the robot's emotional expression with two axes, arousal and valence.