Use of gesture sequences in chimpanzees

Gestural communication in a group of 19 captive chimpanzees (Pan troglodytes) was observed, with particular attention paid to gesture sequences (combinations). A complete inventory of gesture sequences is reported. The majority of these sequences were repetitions of the same gestures, which were often tactile gestures and often occurred in play contexts. Other sequences combined gestures within a modality (visual, auditory, or tactile) or across modalities. The emergence of gesture sequences was ascribed to a recipient's lack of responsiveness rather than a premeditated combination of gestures to increase the efficiency of particular gestures. In terms of audience effects, the chimpanzees were sensitive to the attentional state of the recipient, and therefore used visually-based gestures mostly when others were already attending, as opposed to tactile gestures, which were used regardless of whether the recipient was attending or not. However, the chimpanzees did not use gesture sequences in which the first gesture served to attract the recipient's visual attention before they produced a second gesture that was visually-based. Instead, they used other strategies, such as locomoting in front of the recipient, before they produced a visually-based gesture.