The dual function of social gaze.

Ears cannot speak, lips cannot hear, but eyes can both signal and perceive. For human beings, this dual function makes the eyes a remarkable tool for social interaction. For psychologists trying to understand eye movements, however, their dual function causes a fundamental ambiguity. In order to contrast signaling and perceiving functions of social gaze, we manipulated participants' beliefs about social context as they looked at the same stimuli. Participants watched videos of faces of higher and lower ranked people, while they themselves were filmed. They believed either that the recordings of them would later be seen by the people in the videos or that no-one would see them. This manipulation significantly changed how participants responded to the social rank of the target faces. Specifically, when they believed that the targets would later be looking at them, and so could use gaze to signal information, participants looked proportionally less at the eyes of the higher ranked targets. We conclude that previous claims about eye movements and face perception that are based on a single social context can only be generalized with caution. A complete understanding of face perception needs to address both functions of social gaze.