Emotional or Social?

The behavior of a social robot is designed based on either its emotional state or social situation. In this research, we defined these expressions as the affective and social expressions, and proposed a new emotional expression method to integrate these two expressions. It is known that a human has involuntary facial muscles around the eyes, and voluntary facial muscles around the mouth. Thus, it is considered that facial muscles around the eyes express the affective expressions, while facial muscles around the mouth express the social expressions. In an experiment involving a human-robot conversation, using the proposed method, the results showed a sense of human likeness and sociality. Furthermore, the intimacy evaluation results showed that the social expressions work effectively when the intimacy does not require high social bonding such as the desire for friendship. However, the affective expressions are necessary for evaluating intimacy that requires higher social bonding, such as wanting to live with someone.