Abstract # 132:

Scheduled for Saturday, June 21, 2008 09:00 AM-09:15 AM: Session 14 (Meeting Room 1GHI) Oral Presentation

The rank ordering problem in primate foraging

C. R. Menzel1, E. W. Menzel, jr.2, J. W. Kelley1, B. Chan1, T. A. Evans1 and B. W. Stone3
1Language Research Center, Georgia State Univ., 3401 Panthersville Rd., Decatur, GA 30034, USA, 2Stony Brook University, 3University of Georgia
     The rank ordering problem in foraging is: Given resources that vary in quality, quantity, proximity, visibility, and other dimensions, generate a single dimension of expected value, prioritize the locations along this dimension, and visit the resources sequentially according to their ranking. The basic problem, then, amounts to a psychometric scaling of objects and environmental properties. The rank ordering problem in foraging is illustrated here by two studies. In Study 1, chimpanzees watched as an experimenter placed 10 transparent containers per trial in unique locations in a forest. Each container held 2, 4, 8, 16, or 32 food pieces. Half of the containers were hidden from sight as they were placed on the ground. The other half were left visible. Later, the chimpanzee recruited otherwise uninformed caregivers and directed them to each of the containers. The sequence in which containers were recovered was highly orderly and far more efficient than expected by chance [Friedman Test, a=0.01]. The chimpanzees prioritized the locations, balancing food quantity and visibility. In Study 2, brown capuchins were analogously presented with 8 food items outside their cage. Capuchins used a joystick-controlled laser pointer to direct their caregiver to each food item in turn. The sequence of their choices clearly and quite systematically took into account food type, size, and distance. Supported by HD-38051, HD-056352, the Leakey Foundation, and the Wenner-Gren Foundation.