Infant‐Directed Communication in Lowland Gorillas (Gorilla gorilla): Do Older Animals Scaffold Communicative Competence in Infants?

Abstract

Infant-directed speech is a linguistic phenomenon in which adults adapt their language when addressing infants in order to provide them with more salient linguistic information and aid them in language acquisition. Adult-directed language differs from infant-directed language in various aspects, including speech acoustics, syntax, and semantics. The existence of a "gestural motherese" in interaction with infants, demonstrates that not only spoken language but also nonvocal modes of communication can become adapted when infants are recipients. Rhesus macaques are so far the only nonhuman primates where a similar phenomenon to "motherese" has been discovered: the acoustic spectrum of a particular vocalization of adult females may be altered when the addressees are infants. The present paper describes how gorillas adjust their communicative strategies when directing intentional, nonvocal play signals at infants in the sense of a "nonvocal motherese." Animals of ages above infancy use a higher rate of repetitions and sequences of the tactile sensory modality when negotiating play with infants. This indicates that gorillas employ a strategy of infant-specific communication.

The hand-on gesture in gorillas (Gorilla gorilla)

“…Similar to other gesture studies, the intentionality of signaling was proposed when the sender established eye contact (either before, during, or shortly after the placement of the signal) and waited for a response from the receiver (Pika et al 2003). We recorded a total of twenty-two distinct gestures (see Luef & Liebal 2012) and singled out the hand-on gesture for separate analysis in the present paper. We closely follow definitions of previous studies (see Introduction) and define the hand-on as "placing the hand on the head of another individual for longer than one second".…”

Triadic interactions with tools in a gorilla

“…The described behavior was observed during data collection for a study of communicative behavior in western lowland gorillas from captive groups at Howletts Wild Animals Park in Kent, United Kingdom (for details see Luef & Liebal, 2012.…”

“…While pointing with the index finger can be observed in language-trained gorillas, a group of captive zoo gorillas uses a knocking or pounding gesture to point out locations and objects to conspecifics (Tanner et al, 2006). However, other studies of gorilla gestures in captivity (Luef & Liebal, 2012;Pika, 2007;Pika, Liebal, & Tomasello, 2003) and in the wild (Genty, Breuer, Hobaiter, & Byrne, 2009) did not report any type of referential gestures in the natural communication of gorillas. In an experimental task that elicited requesting (including pointing) gestures in all four great ape species, gorillas were shown to produce the least amount of pointing gestures and tended to engage their human partner in a communicative bout less often than the other great apes (Pelé, Dufour, Thierry, & Call, 2009).…”

“Giving” and “responding” differences in gestural communication between nonhuman great ape mothers and infants

“…The current study aims to establish rudimentary communicative patterns in these early social encounters, through considering the gestural prevalence and response behavior between mother and infant; relative to their communication to other group members. Studies incorporating the recipient (rather than sender) perspective have only relatively recently emerged (Slocombe, Waller, & Liebal, ) and, as of yet, have not incorporated different ape species or targeted the mother–infant dyad (Cartmill & Byrne, ; Hobaiter & Byrne, ; Luef & Liebal, , ; Pollick & de Waal, ; Roberts et al, ; cf., Fröhlich et al, ).…”