An 8-year longitudinal study of mirror self-recognition in chimpanzees (Pan troglodytes).
In a previous cross-sectional study of mirror self-recognition involving 92 chimpanzees, Povinelli et al. [Journal of Comparative Psychology 107 (1993) 347] reported a peak in the proportion of animals exhibiting self-recognition in the adolescent/young adult sample (8-15 years), with 75% being classified as positive. In contrast, only 26% of the older animals (16-39 years) were classified as positive, suggesting a marked decline in self-recognition in middle to late adulthood. In the present study, all of the chimpanzees from the 8-15-year-old group in the Povinelli et al. study (n=12) were again tested for self-recognition, 8 years later. Using the same criteria, 67% of the animals were classified the same. Although a higher proportion of the adult animals in this study (50%) exhibited self-recognition than would be inferred on the basis of the previous study (25%), all changes in self-recognition status were in the negative direction. These results show that mirror self-recognition is a highly stable trait in many chimpanzees, but may be subject to decline with age. Connections with human research are briefly discussed.
de Veer
Monique W
MW
Animal Welfare Centre, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
Gallup
Gordon G
GG
Theall
Laura A
LA
van den Bos
Ruud
R
Povinelli
Daniel J
DJ
D000375:Aging / Q000523:psychology*; D000818:Animals; D003210:Concept Formation; D005260:Female; D008137:Longitudinal Studies; D002679:Pan troglodytes / Q000523:psychology*; D010364:Pattern Recognition, Visual; D012649:Self Concept