Creating genuine smiles for digital and robotic characters: An empirical study

Facial expressions are important cues of people´s emotions, attitudes, and intentions. Smiling is one of the most common facial expressions and is often associated with a welcoming, positive attitude. In social interactions, people sometimes fake their smiles for this effect, and phony fake smiles can often be detected by others. In this work, we explore creating smiles for digital and robotic s characters that seem genuine. In our study, we used male and female digital characters and a Zeno boy robot that is a humanoid robot with facial muscles. We systematically varied the overall length and the apex length of the smiles and examined people´s perceptions of them. Our results indicate that smiles with longer apex lengths appear more genuine and less fake to people for both digital characters and social robots, and 5s seems to be the optimal length of a genuine smile.