Abstract # 20:

Scheduled for Saturday, September 19, 2009 09:15 AM-09:25 AM: Session 3 (Del Mar Room) Oral Presentation


S. Braccini1, S. P. Lambeth2, S. J. Schapiro2 and W. T. Fitch1
1Centre for Social Learning and Cognitive Evolution and Scottish Primate Research Group, School of Psychology, University of St Andrews, Fife, Scotland KY16 9JP, USA, 2Michale E. Keeling Center for Comparative Medicine and Research, The University of Texas M. D. Anderson Cancer Center, Bastrop, Texas 78602, USA

Numerous studies have investigated the lateralization of motor function in great apes, but very few have examined visual laterality. In addition, the hemispheric asymmetry of emotional perception has been proposed in theories such as the valence theory, but no consensus has been reached regarding the role of the individual hemispheres. This study examines eye preference for various stimuli in 45 captive chimpanzees (Pan troglodytes). Eye preference was assessed using a single eye viewing box task with an empty box, a mirror, a picture of a dog, a rubber snake, dry food biscuits, bananas, a rubber duck, and a camera serving as stimuli. Main effects of stimuli were found for both eye preference direction and strength [ANOVA, p<0.01]. A significant left eye bias (primarily right hemisphere) was found for the fear inducing rubber snake and a significant right eye bias (primarily left hemisphere) was found for viewing the desirable bunch of bananas [t-test, p<0.01]. Eye preference strength in the current study is consistent with reports in other species, yet the directional preferences are not always consistent with previous literature. The stimuli likely to evoke the strongest emotional responses showed the strongest directional preferences, a scary snake and a highly desirable bunch of bananas, supporting the valence theory. No relationship between eye preference and previously determined hand preference was found.