Empirical investigation of the temporal relations between speech and facial expressions of emotion

Abstract

Behavior models implemented within Embodied Conversational Agents (ECAs) require nonverbal communication to be tightly coordinated with speech. In this paper we present an empirical study seeking to explore the influence of the temporal coordination between speech and facial expressions of emotions on the perception of these emotions by users (measuring their performance in this task, the perceived realism of behavior, and user preferences).We generated five different conditions of temporal coordination between facial expression and speech: facial expression displayed before a speech utterance, at the beginning of the utterance, throughout, at the end of, or following the utterance. 23 subjects participated in the experiment and saw these 5 conditions applied to the display of 6 emotions (fear, joy, anger, disgust, surprise and sadness). Subjects recognized emotions most efficiently when facial expressions were displayed at the end of the spoken sentence. However, the combination users viewed as most realistic, preferred over others, was the display of the facial expression throughout speech utterance. We review existing literature to position our work and discuss the relationship between realism and communication performance. We also provide animation guidelines and draw some avenues for future work.