The role of (observed) gaze behaviour in identity recognition.

Recognising familiar people is an important function of the human visual system that supports daily social interactions. In addition to static visual cues (e.g., face shape and texture), biological motion cues such as idiosyncratic facial motion and gait contribute to identity recognition. Surprisingly, recent research has indicated an individuals' eye movements exhibit idiosyncratic patterns that contain identifiable information, though it is largely unknown to what extent human observers exploit this information. The current study measures sensitivity of human observers to idiosyncratic gaze behaviours when identifying familiar faces. In two experiments, participants familiarised themselves with faces that were generated from three-dimensional scans of human heads. As participants examined each face, the face's eye movements were animated using eye-tracking data from real observers such that the face appeared to be looking around the room. Participants were then tested on how much had been learned about each identity's gaze behaviours. In Experiment 1 (N = 40), we found a small but significant effect of gaze behaviour in spontaneously biasing the perceived facial identity even when other visual cues to facial identity were available. In Experiment 2, participants (N = 51) were sensitive at discriminating the identity of a face based purely on its eye movements after explicit instructions to rely on gaze behaviour to distinguish different individuals. Our results demonstrate an individual's dynamic gaze behaviours can inform how others recognise them, expanding current understanding of the visual cues that contribute to identity recognition and the sensitivity of human observers to others' attentional behaviour.