Multimodal communication by captive chimpanzees (Pan troglodytes)

Abstract

Many studies have shown that apes and monkeys are adept at cross-modal matching tasks requiring the subject to identify objects in one modality when information regarding those objects has been presented in a different modality. However, much less is known about non-human primates' production of multimodal signaling in communicative contexts. Here, we present evidence from a study of 110 chimpanzees demonstrating that they select the modality of communication in accordance with variations in the attentional focus of a human interactant, which is consistent with previous research. In each trial, we presented desirable food to one of two chimpanzees, turning midway through the trial from facing one chimpanzee to facing the other chimpanzee, and documented their communicative displays, as the experimenter turned towards or away from the subjects. These chimpanzees varied their signals within a context-appropriate modality, displaying a range of different visual signals when a human experimenter was facing them and a range of different auditory or tactile (attention-getting) signals when the human was facing away from them; this finding extends previous research on multimodal signaling in this species. Thus, in the impoverished circumstances characteristic of captivity, complex signaling tactics are nevertheless exhibited by chimpanzees, suggesting continuity in intersubjective psychological processes in humans and apes.

From Grasping to Grooming to Gossip: Innovative Use of Chimpanzee Signals in Novel Environments Supports Both Vocal and Gestural Theories of Language Origins

“…In a recent review, Owren and his colleagues (Owren et al 2011) have suggested that other primates do display apparent voluntary control of mostly non-voiced calls. This conclusion is consistent with our own findings that chimpanzees display a spontaneous and manifest choice over the sensory modality of their signalling behaviour, in some experimental circumstances (Hopkins et al 2007a, b;Leavens et al 2004Leavens et al , 2010. Moreover, several other lines of evidence converge on the conclusion that great apes have voluntary control over some of their calls [see Hopkins et al (2011), for a recent review].…”

“…Thus, chimpanzees will display attention-getting calls or other sounds, if an experimenter is facing away from them, but then switch to manual gestures or other visual signals when the experimenter turns to look directly at them (Bodamer and Gardner 2002;Hostetter et al 2001;Krause and Fouts 1997;Leavens et al 2004Leavens et al , 2010McCarthy et al 2013). Moreover, chimpanzees choose from qualitatively different categories of calls depending on the specific circumstances; if presented with a banana placed outside their cage, but no human, they display species-typical food calls, but if an inattentive human is also present with a banana, the apes display a variety of attention-getting behaviours, including a number of calls that have not been described in these kinds of contexts in wild great apes (Hopkins et al 2007b).…”

Vocal greeting behaviour in wild chimpanzee females

“…Our study does not fit well with the notion of structurally rigid, contextually inflexible and cognitively uninteresting vocal communication (Arbib et al 2008;Tomasello 2008). More likely, both gestural communication and vocal communication are susceptible to the same cognitive processes and architecture that govern social behaviour in primates (Leavens et al 2004(Leavens et al , 2010Slocombe & Zuberbühler 2007;Townsend et al 2008).…”

Learned vocal and breathing behavior in an enculturated gorilla

“…Several studies of captive chimpanzees (described above) reported their use of novel vocalizations and nonvocal sounds as voluntarily controlled attention getters with human interactants (Hopkins, et al 2007;Leavens et al 2004Leavens et al , 2010. These learned sounds included an unvoiced raspberry and also a voiced extended grunt, described as a low, loud, guttural sound made with the mouth open (also see Krauss and Fouts 1997, which noted the use of a raspberry as an attention getter by a sign-taught chimpanzee).…”

“…A set of studies found that captive chimpanzees housed at the Yerkes National Primate Research Center were more likely to use manual gestures to communicate with a visually attentive experimenter, but were more inclined to produce vocalizations and non-vocal sounds when the experimenter was inattentive or facing away (Hopkins et al 2007;Leavens et al 2004Leavens et al , 2010. For example, chimpanzees tactically employed vocalizations in the service of gaining the attention of an inattentive human interlocutor with access to food.…”