Observations on the behavior of gibbons (Hylobates leucogenys, H-gabriellae, and H-lar) in the presence of mirrors

Three captive gibbons (Hylobates leucogenys, H. gabriellae, and H. lar) wer e videotaped in the course of longitudinal exposure to mirrors introduced i nto their familiar cage or island housing situation. The gibbons, which dif fered in age, sex, species, and rearing condition, exhibited great individu al differences in their behavioral reactions to mirrors, spanning from a mi nimal reaction dominated by social responses to a dramatic sequence of prog ressive behavioral change that featured a variety of contingency testing be haviors and included mirror-mediated, self-directed behavior. Additional in formation on the mirror competence of gibbons was provided by modified mark tests and a hidden object task. The results are discussed in relation to c urrent criteria for self-recognition in primates and factors involved in in dividual and species differences in reactions to mirror exposure.