Abstract # 110:

Scheduled for Friday, June 20, 2008 05:00 PM-07:00 PM: Session 12 (Ball Rooms A and B) Poster Presentation

The Sound of One Hand Clapping: Further Evidence of Right-Handedness for Communicative Signaling in Captive Chimpanzees

A. Meguerditchian1,2, M. J. Gardner3, S. J. Schapiro3 and W. D. Hopkins2,4
1University of Provence, Department of Psychology, Research Center in Psychology of Cognition, Language & Emotion, 29, Av. R Schuman, Aix-en-Provence 13621, France, 2Division of Psychobiology, Yerkes National Primate Research Center, Atlanta, GA, 3Department of Veterinary Sciences, M.D. Anderson Cancer Center, Bastrop, TX, 4Department of Psychology, Agnes Scott College, Decatur, GA
     Previous studies of captive chimpanzees have reported population-level right-handedness for manual gestures and that these behaviors are more strongly lateralized than non-communicative motor actions. In the present study, we further tested this observation by examining hand preference for another potentially communicative gesture, clapping. Captive apes use clapping to capture the attention of an otherwise inattentive audience. We recorded hand use for clapping among 79 captive chimpanzees from two research facilities (Yerkes NPRC and UTMDACC). The 57 female and 22 male subjects ranged in age from 5 to 50 years old; 63 were mother-reared and 16 nursery-reared. The preferred hand for clapping was defined as the one in the upper position when the two hands came together. When considering the entire sample, there were significantly more right- compared to left-handed individuals, [c2(1)=4.62, p<0.04]. We found no evidence of a sex difference in hand preference for clapping, and the distribution of right- and left-handed individuals did not differ between the two facilities. Moreover, the number of observations did not influence the expression of hand use because hand use was strongly and almost exclusively lateralized. Correlational analyses indicated that hand use for clapping was significantly positively correlated with handedness for species-typical manual gestures [r(77)=0.46, p<0.05] but not for non-communicative motor actions [r(77)=-0.02, n.s.]. The results are consistent with the view that communicative behaviors induce stronger asymmetries in chimpanzees than other behavioral dimensions of handedness.