SELF-RECOGNITION IN CHIMPANZEES (PAN-TROGLODYTES) - DISTRIBUTION, ONTOGENY, AND PATTERNS OF EMERGENCE

Investigations of mirror self-recognition (SR) in chimpanzees (Pan tro glodytes) have had small samples and divergent methods. In Experiment 1, 105 chimpanzees (10 months to 40 years of age) were observed for si gns of SR across 5 days of continuous mirror exposure. In Experiments 2 and 3, negative SR adult and adolescent chimpanzees were saturated w ith mirror exposure in efforts to facilitate SR and a longitudinal stu dy was conducted with a number of young subjects. In Experiment 4, mar k tests were administered to groups of positive SR, negative SR, and a mbiguous SR subjects. In Experiment 5, we explored whether previous po sitive SR reports in young chimpanzees were artifacts of increased aro usal during mirror exposure. Results suggest that SR typically emerges at 4.5-8 years of age, at the population level the capacity declines in adulthood, and in group settings SR typically occurs within minutes of a subject's exposure to a mirror.