Abstract # 96:

Scheduled for Friday, June 18, 2010 07:00 PM-09:00 PM: Session 18 (Medallion Ballroom C/D/E/F) Poster Presentation


Q. Liu1, E. Visalberghi2 and D. Fragaszy1
1University of Georgia, Department of Psychology, Athens, GA 30602, USA, 2Unit of Cognitive Primatology and Primate Center, Institute of Cognitive Sciences and Technologies, Rome, Italy

Systematic selection of materials for a task requires perceptual judgment of alternatives. Anvils provide a surface to place nuts during cracking. The current study examined if and how nine wild capuchin monkeys selected pits in novel log anvils and the parameters guiding their selections. We presented habituated monkeys with sets of three logs, each containing one manufactured pit, spaced in a triangle around a hammer stone and nut. The pits varied in diameter (small, medium and large) in experiment 1 and in depth (shallow, medium and deep) in experiment 2. We coded the monkeys’ actions with the nut in each pit and the outcome of cracking. Results showed the monkeys rarely used small and deep pits. They chose the large pits and shallow pits more often than medium pits [t-tests: P<0.05]. The monkeys used fewer strikes to open a nut in large and shallow pits than in medium pits [t-tests: P<0.05]. Monkeys rarely touched the pits directly; instead, they detected features of the pits by placing nuts in them and/or by striking nuts in them with stones. They were more likely to switch to a different pit when their initial choice was an ineffective pit (small, medium, deep) than when their initial choice was effective (big or shallow). We conclude that the monkeys detected affordances of the pits through indirect actions with stone and nuts.