The development of the ability to perceive gaze direction was studied in a nursery-reared infant gibbon (Hylobates agilis). We used a head turning procedure that measured the infant's eye and head tracking of moving stimuli. In Experiment 1, we determined how sensitive the subject was at distinguishing between direct and averted gaze in the context of an upright face, an inverted face, and a scrambled face. The subject preferentially looked at the face with a directed gaze over one with an averted gaze irrespective of the surrounding face context. Experiment 2 tested the infant's sensitivity to the existence of eyes in a face. The infant looked at the face containing eyes over no-eyes. These findings suggest that there might be similarities in the early ability to perceive eye direction in humans and gibbons.

Key words: infant gibbon, gaze direction, eye detection, face recognition