Abstract # 135:

Scheduled for Sunday, September 18, 2011 10:30 AM-10:45 AM: Session 18 (Meeting Room 410) Oral Presentation


L. M. Hopper1,2, S. P. Lambeth2, S. J. Schapiro2 and S. F. Brosnan1,2
1Georgia State University, Language Research Center, Department of Psychology, Atlanta, GA 30302, USA, 2Michale E Keeling Center for Comparative Medicine and Research, UT MD Anderson Cancer Center, Bastrop, TX, 78602
     Chimpanzees are reported to remain fixed on a strategy, even if a novel, more efficient, one is introduced. We provide the first evidence that chimpanzees show such ‘conservatism’ even when the new method employs an already-known behavior. Mixed-sex groups of captive chimpanzees (n1 = 7, n2 = 5) could exchange one of two types of inedible token, with each type rewarded with a specific food: highly preferred grapes or less preferred carrot pieces. Chimpanzees first observed a dominant female from their group trained to only exchange one token type before their group had access to both types. In one group, the seeded token type earned carrot, while in the other it earned grapes. Across 10 hours, during which the chimpanzees had access to tokens, both groups conformed to their model’s choice (P < 0.001). This was especially striking for those gaining the less favored carrot, in which group the majority of chimpanzees discovered the alternative, better rewarded, token yet continued to exchange the seeded type. This population-level trend was maintained even when counter to chimpanzees’ original, individual, food preferences. Moreover, the chimpanzees’ food preferences did not change over time, demonstrating that this was not due to a shift in preferences. The interplay between conservatism and conformity will be discussed. We suggest that, despite seeming inefficient, conformity may benefit chimpanzees, possibly by maintaining group relations.