Robot Laughter: Does an appropriate laugh facilitate the robot's humor performance?

Laughter serves as a subtle social signal in human interaction, playing an essential role in expressing emotions and facilitating social connections. However, laughter comes in various forms and is usually accompanied by different non-verbal expressions, such as facial expressions and gestures. These accompanying factors can significantly influence the effect of laughter in diverse contexts, thus complicating the research on laughter, especially in understanding its role in social dynamics. Consequently, endowing robots with the ability to appropriately use laughter in interactions with humans is still a big challenge. Our current study focuses on the effect of robot laughter on robot humor expression. Our objective is to investigate whether and how two factors, the type of laughter and the robot laughter gesture, impact the overall humor performance. In this study, we selected four types of laughter (sarcastic, joyful, embarrassed, and relieved laughter) from a laughter corpus based on four specific types of jokes (Affiliative, Aggressive, Self-enhancing, and Self-defeating). For each type of laughter, we designed distinct robot gestures. During the humor performance, the robot NAO delivered jokes accompanied by matching or mismatching laughter, with or without corresponding gestures. To enhance the quantity and diversity of experimental data, we conducted an online survey utilizing recordings of the robot's humor performance. The experimental findings indicate that when the robot's laughter matches the type of humor in the joke, participants rate the humor performance significantly higher compared to situations where there is a mismatch. Additionally, the results confirm the positive impact of robot laughter gestures on humor performance.