What Kinds of Robot's Touch Will Match Expressed Emotions?

This study investigated the effects of touch characteristics that change the strength and the naturalness of the emotions perceived by people in human-robot touch interaction with an android robot that has a feminine, human-like appearance. Past studies on human-robot touch interaction focused on understanding what kinds of human touches conveyed emotion to robots, i.e., the robot's touch characteristics that can affect people's perceived emotions received less focus. In this study, we concentrated on three touch characteristics (length, type, and part) based on arousal/valence perspectives, and their effects on the perceived strength/naturalness of a commonly used emotion in human-robot interaction, i.e., happiness, and its counterpart emotion, (i.e., sadness), borrowing Ekman's definitions. Our results showed that the touch length and its type are useful to change the perceived strengths and the naturalness of the expressed emotions based on the arousal/valence perspective, although the touch part did not fit such perspective assumptions. Finally, our results suggest that a brief pat and a longer contact by the fingers are better combinations to express happy and sad emotions with our robot. Since we only used a female android, we discussed future works with a male humanoid robot and/or a robot whose appearance is less humanoid.