Yohanan, S., "The Haptic Creature: Social Human-Robot Interaction through Affective Touch," Ph.D. Thesis, University of British Columbia, 2012.
Emotion communication is an important aspect of social interaction. Affect display research from psychology as well as social human-robot interaction has focused primarily on facial or vocal behaviors, as these are the predominant means of expression for humans. Much less attention, however, has been on emotion communication through touch, which, though unique among the senses, can be methodologically and technologically difficult to study. Our thesis investigated the role of affective touch in the social interaction between human and robot. Through a process of design and controlled user evaluation, we examined the display, recognition, and emotional influence of affective touch. To mitigate issues inherent in touch research, we drew from interaction models not between humans but between human and animal, whereby the robot assumes the role of companion animal. We developed the Haptic Creature, a small, zoomorphic robot novel in its sole focus on touch for both affect sensing and display. The robot perceives movement and touch, and it expresses emotions through ear stiffness, modulated breathing, and vibrotactile purring. The Haptic Creature was employed in three user studies, each exploring a different aspect of affective touch interaction. Our first study examined emotion display from the robot. We detail the design of the Haptic Creature's affect display, which originated from animal models, then was enhanced through successive piloting. A formal study demonstrated the robot was more successful communicating arousal than valence. Our second study investigated affect display from the human. We compiled a touch dictionary from psychology and human-animal interaction research. Participants first rated the likelihood of using these touch gestures when expressing a variety of emotions, then performed likely gestures communicating specific emotions for the Haptic Creature. Results provided properties of human affect display through touch and high-level categorization of intent. Our final study explored the influence of affective touch. Results empirically demonstrated the human's emotional state was directly influenced from affective touch interactions with the robot. Our research has direct significance to the field of socially interactive robotics and, further, any domain interested in human use of affective touch: psychology, mediated social touch, human-animal interaction.