Ujhelyi, M.; Merker, B.; Buk, P. & Geissmann, T. (2000). Observations on the behavior of gibbons (Hylobates leucogenys, H. gabriellae, and H. lar) in the presence of mirrors. Journal of Comparative Psychology 114: 253-262.

Observations on the behavior of gibbons in the presence of mirrors

Mária Ujhelyi ¹, Björn Merker ², Pál Buk ¹ & Thomas Geissmann <sup>3

1</sup> Semmelweis University of Medicine, Institute of Behavioural Sciences, Hungary
² Mid Sweden University, Institute for Biomusicology, Sweden
³ Institute of Zoology, Tierärztliche Hochschule Hannover, Germany

Key Words: Gibbons; self-recognition; mirror-directed behavior; mark test; self-awareness.

Abstract: Three captive gibbons (Hylobates leucogenys, H. gabriellae, and H. lar) were videotaped in the course of longitudinal exposure to mirrors introduced into their familiar cage or island housing situation. The gibbons, which differed in age, sex, species, and rearing condition, exhibited great individual differences in their behavioral reactions to mirrors, spanning from a minimal reaction dominated by social responses to a dramatic sequence of progressive behavioral change that featured a variety of contingency testing behaviors and included mirror-mediated, self-directed behavior. Additional information on the mirror competence of gibbons was provided by modified mark tests and a hidden object task. The results are discussed in relation to current criteria for self-recognition in primates and factors involved in individual and species differences in reactions to mirror exposure.