In this paper, we describe two series of experiments that examine audiovisual face-to-face interaction between naive human viewers and either a human interlocutor or a virtual conversational agent. The main objective is to analyze the interplay between speech activity and mutual gaze patterns during mediated face-to-face interactions. We first quantify the impact of deictic gaze patterns of our agent. We further aim at refining our experimental knowledge on mutual gaze patterns during human face-to-face interaction by using new technological devices such as non-invasive eye trackers and pinhole cameras, and at quantifying the impact of a selection of cognitive states and communicative functions on recorded gaze patterns.