Abstract # 129:

Scheduled for Saturday, June 21, 2008 08:15 AM-08:25 AM: Session 14 (Meeting Room 2DEF) Oral Presentation

Sex differences in mirror self-recognition in chimpanzees (Pan troglodytes)

W. Hopkins1,2
1Yerkes National Primate Res. Ctr., Division of Psychobiology, Emory Univ., 954 Gatewood Road, Atlanta, GA 30329, USA, 2Department of Psychology, Agnes Scott College, 141 E. College Ave, Decatur, Georgia 30030

In 1970, Gordon Gallup reported that chimpanzees exhibit mirror self-recognition (MSR). Additional studies have documented evidence of MSR in other great apes but not in other nonhuman primate species. One important observation on MSR is the fact that there are considerable individual differences in performance on this task. In this study, I examined the influence of rearing history and sex on MSR in a sample of 73 captive chimpanzees. In one experiment, the chimpanzees were given a 30 min exposure to a mirror and their behavior in front of the mirror was recorded and coded for frequency of mirror-guided self exploration. In a follow up experiment, MSR was tested again but using a small LCD from a digital video camera instead of a mirror. In both experiments, females showed higher rates of mirror-guided self exploration compared to males [t-tests, a=0.05]. Moreover, apes that showed higher levels of mirror-guided self exploration displayed significantly higher rates of contingency movements [ANOVA, a=0.01]. Rearing history had no significant influence on MSR in either experiment. Evidence of sex differences in MSR suggests that females may show either greater socio-cognitive abilities or be more exploratory in the presence of the mirror than males. The lack of evidence of sex differences in previous studies on MSR in apes may have been due to a lack of statistical power.