Abstract # 76:

Scheduled for Thursday, August 17, 2006 07:00 PM-09:00 PM: Session 8 (Regency West 1/3 ) Poster Presentation

Between a nut and a hard place: Use of sensory cues by brown capuchins (Cebus apella) in hard nut selection

K. A. Phillips, C. A. Buzzell, A. Cipollone, M. L. Maskulka and N. V. Morgan
Hiram College, Department of Psychology and Biology, 11715 Garfield Rd., Hiram, OH 44234, USA
     Field and laboratory observations indicate that capuchins use an array of investigative behaviors in the detection and selection of food items. To investigate the sensory cues involved in selection, six capuchins were presented with a choice of two walnuts, one full and one modified. Nuts were modified to differ by sound and weight (Phase 1), sound (Phase 2), or weight (Phase 3). For each trial (n=40/phase), choice (first nut opened) and number of investigative behaviors directed at each nut were recorded. We hypothesized that subjects would choose the full walnut more and investigate the full walnut more in all three phases, as determined by chi-square tests. There was no difference in which nut was opened first. In Phase 1, five of six subjects directed significantly more investigative behavior toward the full walnut (p < .05). In Phases 2 and 3, less than half of the subjects investigated the full walnut more (p < .05); the remaining subjects investigated both equally. These results suggest that sensory cues stimulate/motivate investigative behavior. When nuts differed by two cues, subjects focused behavior on the nut that provided more cues. However, nuts differing by one cue elicited equal investigation by the subjects, perhaps indicating an inability to discriminate. While the laboratory condition failed to induce “choice”, increased investigative response to cues likely facilitates selection in the wild.