Abstract # 1018 Event # 7:

Scheduled for Thursday, August 18, 2005 11:00 AM-11:15 AM: Session 1 (Parliament Room) Oral Presentation

Differential Use of Attentional and Visual Communicative Signaling by Orangutans (Pongo pygmaeus) and gorillas (Gorilla gorilla) in Response to the Attentional Status of a Human

S. R. Poss1,2, C. Kuhar3, T. S. Stoinski3,4 and W. D. Hopkins1,5
1Yerkes National Primate Research Center, Yerkes National Primate Research Center, Living Links Center, 954 N. Gatewood Rd, Atlanta, GA 30322, USA, 2Emory University, 3Zoo Atlanta Atlanta, GA, 4Dian Fossey Gorilla Fund International, Atlanta, GA, 5Department of Psychology, Berry College, Mount Berry, Georgia
     This study investigated the communicative abilities of 10 orangutans (Pongo pygmaeus) and 7 gorillas (Gorilla gorilla) particularly focusing on their sensitivity to the attentional state of a human experimenter when choosing from a repertoire of both auditory and visual communication strategies. In Experiment 1, a banana was placed in front of the subject’s cage with a human experimenter either present or absent. Both gorillas and orangutans gestured (t(16) = -3.58, P < 0.005) and vocalized (t(16) = -2.47, P < 0.05) more when the experimenter was present. In Experiment 2, a human experimenter held a banana in front of the subject’s cage and was oriented either toward or away from the subject. In this experiment, both gorillas and orangutans gestured significantly more frequently (t(16) = 3.40, P < 0.005) when an experimenter was oriented toward them as well as used other forms of visual communication signals such as lip pout (t(16) = 3.66, P < 0.005), barter/trade (t(16) = 2.31, P < 0.05), and body presents (t(16) = 2.31, P < 0.05) significantly more when an experimenter was facing them. The overall results indicated that both gorillas and orangutans are sensitive to the attentional state of a human experimenter and use appropriate communicative signals to gain that individual’s attention. These results are similar to results found in terms of communicative behaviors in chimpanzees as well.