title: An 8-year longitudinal study of mirror self-recognition in chimpanzees (Pan troglodytes).
abstract: 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.
authors.affiliation: Animal Welfare Centre, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Monique W
authors.initials: MW
authors.lastname: de Veer
authors.forename: Gordon G
authors.initials: GG
authors.lastname: Gallup
authors.forename: Laura A
authors.initials: LA
authors.lastname: Theall
authors.forename: Ruud
authors.initials: R
authors.lastname: van den Bos
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Povinelli
mesh_terms: 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