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Rendall, D., Cheney, D. L., & Seyfarth, R. M. (2000). Proximate factors mediating “contact” calls in adult female baboons (Papio cynocephalus ursinus) and their infants. J Comp Psychol, 114(1), 36–46.
Abstract: “Contact” calls are widespread in social mammals and birds, but the proximate factors that motivate call production and mediate their contact function remain poorly specified. Field study of chacma baboons (Papio cynocephalus ursinus) revealed that contact barks in adult females were motivated by separation both from the group at large and from their dependent infants. A variety of social and ecological factors affect the probability of separation from either one or both. Results of simultaneous observations and a playback experiment indicate that the contact function of calling between mothers and infants was mediated by occasional maternal retrieval rather than coordinated call exchange. Mothers recognized the contact barks of their own infants and often were strongly motivated to locate them. However, mothers did not produce contact barks in reply unless they themselves were at risk of becoming separated from the group.
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Peake, T. M., Terry, A. M., McGregor, P. K., & Dabelsteen, T. (2001). Male great tits eavesdrop on simulated male-to-male vocal interactions. Proc Biol Sci, 268(1472), 1183–1187.
Abstract: Animal communication generally occurs in the environment of a network of several potential signallers and receivers. Within a network environment, it is possible to gain relative information about conspecifics by eavesdropping on signalling interactions. We presented male great tits with the opportunity to gain such information by simulating singing interactions using two loudspeakers. Interactions were presented so that relevant information was not available in the absolute singing behaviour of either individual, only in the relative timing of their songs in the interaction as a whole. We then assayed the information extracted by focal males by subsequently introducing one of the 'interactants' (i.e. loudspeakers) into the territory of the focal male. Focal males responded with a reduced song output to males that had just 'lost' an interaction. Focal males did not respond significantly differently to 'winners' as compared with intruders recently involved in an interaction that contained no consistent information. Focal males also responded by switching song types more often when encountering males that had recently been involved in a low-intensity interaction. These results provide the clearest evidence yet that male songbirds extract information from signal interactions between conspecifics in the field.
Keywords: Animals; Male; Songbirds/*physiology; *Vocalization, Animal
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Hostetter, A. B., Cantero, M., & Hopkins, W. D. (2001). Differential use of vocal and gestural communication by chimpanzees (Pan troglodytes) in response to the attentional status of a human (Homo sapiens). J. Comp. Psychol., 115(4), 337–343.
Abstract: This study examined the communicative behavior of 49 captive chimpanzees (Pan troglodytes), particularly their use of vocalizations, manual gestures, and other auditory- or tactile-based behaviors as a means of gaining an inattentive audience's attention. A human (Homo sapiens) experimenter held a banana while oriented either toward or away from the chimpanzee. The chimpanzees' behavior was recorded for 60 s. Chimpanzees emitted vocalizations faster and were more likely to produce vocalizations as their 1st communicative behavior when a human was oriented away from them. Chimpanzees used manual gestures more frequently and faster when the human was oriented toward them. These results replicate the findings of earlier studies on chimpanzee gestural communication and provide new information about the intentional and functional use of their vocalizations.
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Peake, T. M., Terry, A. M. R., McGregor, P. K., & Dabelsteen, T. (2002). Do great tits assess rivals by combining direct experience with information gathered by eavesdropping? Proc Biol Sci, 269(1503), 1925–1929.
Abstract: Animals frequently use signals that travel further than the spacing between individuals. For every intended recipient of a given signal there are likely to be many other individuals that receive information. Eavesdropping on signalling interactions between other individuals provides a relatively cost-free method of assessing future opponents or mates. Male great tits (Parus major) extract relative information from such interactions between individuals unknown to them. Here, we show that male great tits can take information gathering a stage further and obtain more information about a previously unencountered intruder, by the hitherto unknown capability of combining information gathered by eavesdropping with that derived from their own direct interaction with an individual. Prior experience with an intruder (A) was achieved by subjecting a focal male to different levels of intrusion simulated using interactive playback. This intruder (A) then took part in a simulated interaction with an unknown male (B) outside the territorial boundary of the focal males. In response to subsequent intrusion by the second male (B), focal males showed low song output in response to males that had lost to a male that the subject was able to beat. Males of known high quality, or those about which information was ambiguous, elicited a high level of song output by focal males. We discuss the implications of this finding for the evolution of communication and social behaviour.
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Fischer, J., Hammerschmidt, K., Cheney, D. L., & Seyfarth, R. M. (2002). Acoustic features of male baboon loud calls: influences of context, age, and individuality. J Acoust Soc Am, 111(3), 1465–1474.
Abstract: The acoustic structure of loud calls (“wahoos”) recorded from free-ranging male baboons (Papio cynocephalus ursinus) in the Moremi Game Reserve, Botswana, was examined for differences between and within contexts, using calls given in response to predators (alarm wahoos), during male contests (contest wahoos), and when a male had become separated from the group (contact wahoos). Calls were recorded from adolescent, subadult, and adult males. In addition, male alarm calls were compared with those recorded from females. Despite their superficial acoustic similarity, the analysis revealed a number of significant differences between alarm, contest, and contact wahoos. Contest wahoos are given at a much higher rate, exhibit lower frequency characteristics, have a longer “hoo” duration, and a relatively louder “hoo” portion than alarm wahoos. Contact wahoos are acoustically similar to contest wahoos, but are given at a much lower rate. Both alarm and contest wahoos also exhibit significant differences among individuals. Some of the acoustic features that vary in relation to age and sex presumably reflect differences in body size, whereas others are possibly related to male stamina and endurance. The finding that calls serving markedly different functions constitute variants of the same general call type suggests that the vocal production in nonhuman primates is evolutionarily constrained.
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Hauber, M. E., Pearson, H. E., Reh, A., & Merges, A. (2002). Discrimination between host songs by brood parasitic brown-headed cowbirds ( Molothrus ater). Anim. Cogn., 5(3), 129–137.
Abstract: Songbirds can learn both to produce and to discriminate between different classes of acoustic stimuli. Varying levels of auditory discrimination may improve the fitness of individuals in certain ecological and social contexts and, thus, selection is expected to mold the cognitive abilities of different species according to the potential benefits of acoustic processing. Although fine-scale auditory discrimination of conspecific songs and calls has been frequently reported for brood parasitic brown-headed cowbirds ( Molothrus ater), it remains unclear why and how they perceive differently the songs of their many host species. Using habituation-dishabituation paradigms and measuring behavioral and physiological (heart-rate) responses, we found that captive female cowbirds consistently discriminated between songs of two host species, the song sparrow ( Melospiza melodia) and the red-winged blackbird ( Agelaius phoeniceus). Playback experiments with stimuli composed of con-specific followed by heterospecific vocalizations in the field also demonstrated discrimination between these heterospecific songs even though cowbirds were not attracted to playbacks of either host species' songs alone. Our results do not directly support a nest-searching function of heterospecific song discrimination by cowbirds and are most consistent with a function of the parasites' avoidance of attacks by their aggressive hosts. These data demonstrate discrimination between heterospecific vocalizations by brown-headed cowbirds and add a novel dimension to the already expansive auditory perceptual abilities of brood parasitic species and other songbirds.
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Seyfarth, R. M., & Cheney, D. L. (2003). Meaning and emotion in animal vocalizations. Ann N Y Acad Sci, 1000, 32–55.
Abstract: Historically, a dichotomy has been drawn between the semantic communication of human language and the apparently emotional calls of animals. Current research paints a more complicated picture. Just as scientists have identified elements of human speech that reflect a speaker's emotions, field experiments have shown that the calls of many animals provide listeners with information about objects and events in the environment. Like human speech, therefore, animal vocalizations simultaneously provide others with information that is both semantic and emotional. In support of this conclusion, we review the results of field experiments on the natural vocalizations of African vervet monkeys, diana monkeys, baboons, and suricates (a South African mongoose). Vervet and diana monkeys give acoustically distinct alarm calls in response to the presence of leopards, eagles, and snakes. Each alarm call type elicits a different, adaptive response from others nearby. Field experiments demonstrate that listeners compare these vocalizations not just according to their acoustic properties but also according to the information they convey. Like monkeys, suricates give acoustically distinct alarm calls in response to different predators. Within each predator class, the calls also differ acoustically according to the signaler's perception of urgency. Like speech, therefore, suricate alarm calls convey both semantic and emotional information. The vocalizations of baboons, like those of many birds and mammals, are individually distinctive. As a result, when one baboon hears a sequence of calls exchanged between two or more individuals, the listener acquires information about social events in its group. Baboons, moreover, are skilled “eavesdroppers:” their response to different call sequences provides evidence of the sophisticated information they acquire from other individuals' vocalizations. Baboon males give loud “wahoo” calls during competitive displays. Like other vocalizations, these highly emotional calls provide listeners with information about the caller's dominance rank, age, and competitive ability. Although animal vocalizations, like human speech, simultaneously encode both semantic and emotional information, they differ from language in at least one fundamental respect. Although listeners acquire rich information from a caller's vocalization, callers do not, in the human sense, intend to provide it. Listeners acquire information as an inadvertent consequence of signaler behavior.
Keywords: Acoustics; *Affect; Animals; Behavior, Animal; *Intention; Posture; Sound Spectrography; *Vocalization, Animal
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Seyfarth, R. M., & Cheney, D. L. (2003). Signalers and receivers in animal communication. Annu Rev Psychol, 54, 145–173.
Abstract: In animal communication natural selection favors callers who vocalize to affect the behavior of listeners and listeners who acquire information from vocalizations, using this information to represent their environment. The acquisition of information in the wild is similar to the learning that occurs in laboratory conditioning experiments. It also has some parallels with language. The dichotomous view that animal signals must be either referential or emotional is false, because they can easily be both: The mechanisms that cause a signaler to vocalize do not limit a listener's ability to extract information from the call. The inability of most animals to recognize the mental states of others distinguishes animal communication most clearly from human language. Whereas signalers may vocalize to change a listener's behavior, they do not call to inform others. Listeners acquire information from signalers who do not, in the human sense, intend to provide it.
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Pepperberg, I. M. (2004). “Insightful” string-pulling in Grey parrots (Psittacus erithacus) is affected by vocal competence. Anim. Cogn., 7(4), 263–266.
Abstract: Four Grey parrots (Psittacus erithacus) were tested on their ability to obtain an item suspended from a string such that mutiple, repeated, coordinated beak-foot actions were required for success (e.g., Heinrich 1995). Those birds with little training in referential English requests (e.g. “I want X”) succeeded, whereas birds who could request the suspended item failed to obtain the object but engaged in repeated requesting.
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Izumi, A., & Kojima, S. (2004). Matching vocalizations to vocalizing faces in a chimpanzee (Pan troglodytes). Anim. Cogn., 7(3), 179–184.
Abstract: Auditory-visual processing of species-specific vocalizations was investigated in a female chimpanzee named Pan. The basic task was auditory-visual matching-to-sample, where Pan was required to choose the vocalizer from two test movies in response to a chimpanzee's vocalization. In experiment 1, movies of vocalizing and silent faces were paired as the test movies. The results revealed that Pan recognized the status of other chimpanzees whether they vocalized or not. In experiment 2, two different types of vocalizing faces of an identical individual were prepared as the test movies. Pan recognized the correspondence between vocalization types and faces. These results suggested that chimpanzees possess crossmodal representations of their vocalizations, as do humans. Together with the ability of vocal individual recognition, this ability might reflect chimpanzees' profound understanding of the status of other individuals.
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