Exploring the Effects of Virtual Agents’ Smiles on Human-Agent Interaction: A Mixed-Methods Study

Artificial agents’ smiling behaviour is likely to influence their likeability and the quality of user experience. While studies of human interaction highlight the importance of smile dynamics, this feature is often lacking in artificial agents, presenting a design opportunity. We developed a virtual motivational therapist with four smiling behaviours, varying in terms of quality and dynamism . We video-recorded experimental sessions with participants who posed as patients in a therapy session. The data were analysed combining a mix of quantitative and qualitative methods, focusing on participants’ own facial expressions during the interaction. Results suggest that the condition driven using data from a real therapist, where smiles are dynamic and occur at specific moments, is the most effective. We further discuss the particular importance of smile as a multipurpose emotional display in human-machine interaction.