Abstract # 9:

Scheduled for Thursday, August 18, 2005 11:30 AM-11:45 AM: Session 1 (Parliament Room) Oral Presentation

Referential Potential of Chimpanzee (Pan troglodytes) Food Barks

C. M. Gibbons, K. L. Holland and S. T. Boysen
The Ohio State University, Department of Psychology, 238 Townshend Hall, 1885 Neil Ave. Mall, Columbus, OH 43210, USA
     To explore the degree to which chimpanzee (Pan troglodytes) food vocalizations may potentially reference specific foods, or more reflect categorical food quality, a replication and elaboration of Hallberg et al. (2003) was completed. Five adult chimpanzees housed at the Ohio State University Chimpanzee Center were presented with 36 food barks that were collected as a larger sample. Vocal samples used included 4 different exemplars (recorded from different animals) representing each of 9 foods, including 3 high value, 3 moderate, and 3 low value items. All presentations of the vocalizations were randomized over nine test sessions, 16 trials each, for a total of 144 vocalizations. Individual vocalizations were presented 16 times to each subject. On a given trial, immediately after presentation of the vocal stimulus, four color photos of different foods were displayed in a 2 x 2 matrix via computer-interfaced touch-frame system and monitor. The chimps were rewarded for whatever choice they made to minimize learning effects, and ideally, selected the photo that matched the food vocalization being presented. Overall results indicated that the animals were statistically significant in choosing photographs representing specific foods (P < 0.01) and food quality category (P < 0.01). Subsequent acoustic analyses of the vocal stimuli identified the significant features that likely contributed to specific and categorical vocalization judgments. Results suggest that these subjects derived referentially specific information from the food vocalizations presented.