Chimpanzees, Pan troglodytes, follow gaze direction geometrically

Two experiments on chimpanzee gaze following are reported. In the first, ch impanzee subjects watched as a human experimenter looked: around various ty pes of barriers. The subjects looked around each of the barriers more when the human had done so than in a control condition (in which the human looke d in another direction). In the second experiment, chimpanzees watched as a human looked towards the back of their cage. As they turned to follow the human's gaze a distracter object was presented. The chimpanzees looked at t he distracter while still following the human's gaze to the back of the cag e. These two experiments effectively disconfirm the low-level model of chim panzee gaze following in which it is claimed that upon seeing another anima te being's gaze direction chimpanzees simply turn in that direction and loo k around for something interesting. Rather, they support the hypothesis tha t chimpanzees follow the gaze direction Of other animate beings geometrical ly to specific locations, in much the same way as human infants. The degree to which chimpanzees have a mentalistic interpretation of the gaze and/or visual experience of others is still an open question. (C) 1999 The Associa tion for the Study of Animal Behaviour.