Manipulating social cues in baboon gesture learning: what does it tell us about the evolution of communication?

Reading the attentional state of an audience is crucial for effective intentional communication. This study investigates how individual learning experience affects subsequent ability to tailor gestural communication to audience visual attention. Olive baboons were atypically trained to request food with gestures by a human standing in profile, while not having access to her face. They were tested immediately after training, and then 1year later in conditions that varied the human's cues to attention. In immediate testing, these baboons (profile group baboons) gestured towards untrained cues regardless of their relevance for visual communication. They were also less discriminant towards trained versus untrained cues than baboons trained by a human facing them (face group baboons, tested in Bourjade et al. Anim Behav 87:121-128; Bourjade et al., Anim Behav 87:121-128, 2014). In delayed testing, the number of gestures towards meaningful untrained cues increased and profile group baboons discriminated the orientation of the human body, a conspicuous proxy of visual attention. Our results provide support for the primary interplay between implicit learning and systematically reinforced associations made through explicit training in the scaffolding of intentional gesturing tuned to audience attention.