Abstract 9514001 Cheney The goal of this research is a better understanding of the vocal communication and social behavior of freeranging nonhuman primates. Focus will be on vocal communication for a variety of reasons: first, because of its potential relation to studies of language and cognition in humans; second, because vocalizations lend themselves to quantitative signal analysis and to experimental tests of specific hypotheses. Finally, prior research has shown that playback experiments can be used to test hypotheses not only about vocal communication per se but also about the cognitive mechanisms that underlie complex social interactions. Subjects are free-ranging baboons (Papio cynocephalus ursinus) living in the Okavango Delta, Botswana. Animals in the study population are fully habituated to human observers, are recognized as individuals, and have known reproductive histories. The proposal has five inter-related components. The first component of this proposal focuses on the use of vocalizations in reconciliation. After aggression, female baboons sometimes 'reconcile' by grunting to their lower-ranking opponents. Previous experiments have shown that these grunts function at least in part to reduce former victims' anxiety. A second component focuses on the acoustic structure and possible semantic content of grunts. Baboons appear to use acoustically different grunts in different social situations. The PIs plan a series of observations and experiments are planned to determine whether acoustically different grunt types designate specifically different information to baboons. A third component focuses on contact barks that appear to be exchanged between mothers and infants when they become separated in wooded areas. If these experiments indicate that mothers give contact barks primarily with respect to their own (rather than their infants') location, then they will add to a growing body of evidence suggesting that nonhuman primates do not call with the intent of providing inform ation to others. A fourth component focuses on the view that pair bonds are formed in response to the threat of infanticide by recent immigrant males. These experiments, however, are incomplete, largely because they must be conducted opportunistically during the weeks after a new, potentially infanticidal male has joined the group. A fourth goal of the research will be to complete these experiments. The final component focuses on the perception of cause-effect relations by nonhuman primates. Humans readily distinguish between two events that occur together because one caused the other and two events that occur together purely by association. Most research conducted to date suggests that monkeys do not apply causal reasoning when manipulating tools, though language-trained apes perform markedly better on similar experiments. Previous experiments conducted with this group of baboons, however, suggest that monkeys' ability to perceive cause-effect relations in the domain of social interactions may be quite well developed. Female baboons respond significantly more strongly to playbacks of vocal sequences that are causally anomalous than to those that are not. To investigate this question further, a series of experiments is proposed that make explicit predictions about both the strength and the timing of subjects' responses to particular call sequences. ***
