Abstract # 203:

Scheduled for Monday, September 21, 2009 11:00 AM-11:10 AM: Session 20 (Del Mar Room) Oral Presentation


S. F. Brosnan1,2, C. Talbot2, S. P. Lambeth2 and S. J. Schapiro2
1Georgia State University, Department of Psychology, Neuroscience Institute, Atlanta, GA 30303-5010, USA, 2Michale E Keeling Center for Comparative Medicine and Research, The University of Texas MD Anderson Cancer Center, Bastrop, TX USA

Several species of nonhuman primates appear to respond negatively to inequity. However, this response is sensitive to external contingencies. For instance, a task of some sort appears to be necessary to prime the response, perhaps indicating that it evolved in the context of joint effort, or cooperation. Moreover, there is a tradeoff between ‘individual’ expectations (based on one’s own previous experience) and ‘social’ expectations (based on the partners’ experience), with individuals responding to both to varying degrees. In this study, we investigate both of these questions in sixteen [10 male, 6 female] socially-housed adult chimpanzees. Subjects were given eight conditions, which included conditions with both individual and social expectation violations as well as those with and without a task (an exchange). There was overall variation between the conditions in willingness to complete the interaction [Repeated measures ANOVA: F(7,18)=7.49, p<0.001], with an interaction with sex [F(7,18)=3.51, p=0.015]. Males were more sensitive to social than individual expectation [T+=84.5, p=0.004], while females were more sensitive to individual expectation [T+=36, p=0.008]. Males responded to social expectation only when a task was involved [T+=171, p<0.001; females responded in neither variation]. These results indicate that there is interplay between social and individual expectations dependent upon social environment.