Having access to others' mind through gaze: the role of ontogenetic and learning processes in gaze-following behavior of macaques.

In primates the gaze conveys important information about what others attend to and about their intentions. The ability to follow the gaze direction of conspecifics has been established for several primate species. It has been proposed to be a precursor for more complex cognitive skills related to mind reading. Studies in humans and other primates have shown that this behavior develops during the period between infancy and adulthood; however, the mechanisms responsible for its emergence are still unknown. In a series of experiments we investigated such mechanisms in macaques (Macaca nemestrina). Results show that juvenile macaques improve their ability to follow the gaze of a human experimenter and that adults' ability to follow gaze is more accurate than that of juveniles. Our data also show that this behavior can emerge as the result of learning processes. The discrepancy between the relatively long period of time needed for the full establishment of the gaze-following behavior and its high sensitivity to conditioning procedures may suggest that social experience and integration of this behavior with other social-cognitive skills are required for its development.