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