In Your Face, Robot! The Influence of a Character’s Embodiment on How Users Perceive Its Emotional Expressions

The ability of artificial characters to express emotions is essential for the natural interaction with humans. Their absence could be interpreted as coldness towards the user. Artificial characters can have different embodiments. Screen characters and robotic characters are currently among the most widely used. This study investigates the influence of the character’s embodiment on how users perceive the character’s emotional expressions. The results show that there is no significant difference in the perceived intensity and recognition accuracy between a robotic character and a screen character. Another important aspect of the character is its ability to express different emotional intensity levels. Developers create different geometrical intensity levels of emotional expressions by equally dividing the spatial difference of each facial component between the neutral and maximum expression. However, the relationship between this geometrical intensity and the intensity perceived by the user might not be strictly linear. This study shows that also a quadratic trend is present in this relationship and that10% steps increase of geometrical intensity can often be distinguished whereas 20% steps can be distinguished almost all the time. Introduction Many synthetic characters are used for entertainment, communication, and work. They range from movie stars (Thomas & Johnson, 1981) and pets (Sony, 1999) to helper agents (Bell et al., 1997) (see Figure 1) and avatars for virtual cooperative environments (Isbister, Nakanishi, Ishida, & Nass, 2000). Characters can also have a physical body, e.g. robots. The interesting robots for this study help the elderly (Hirsch et al., 2000), support humans in the house (NEC, 2001), improve communication between distant partners (Gemperle, DiSalvo, Forlizzi, & Yonkers, 2003) and are research vehicles for the study on human-robot communication (Breazeal, 2003; Okada, 2001). A survey of relevant characters is available (Bartneck, 2002; Fong, Nourbakhsh, & Dautenhahn, 2003) Bartneck, C., Reichenbach, J., & Breemen, A. (2004). In your face, robot! The influence of a character’s embodiment on how users perceive its emotional expressions. Proceedings of the Design and Emotion 2004, Ankara.