Examining the Use of Auditory Signals as 'Attention-Getters' in Zoo-Housed Gorillas (Gorilla gorilla gorilla) and Orangutans (Pongo pygmaeus and Hybrid)

摘要

"Attention-getters" are proposed to be gestures that function to attract the attention of a recipient and therefore allow further communication to take place. Their use is an indicator of intentional communication and thus of great interest to researchers in the field of language evolution. However, there is conflicting evidence as to whether nonhuman primates use attention-getters, both in conspecific interactions and in interactions with humans. We examined whether zoo-housed orangutans (Pongo pygmaeus and hybrid [Pongo pygmaeus x Pongo abelii]) and gorillas (Gorilla gorilla gorilla) used auditory signals to initiate visual communication with a human. To test this, a human experimenter stood with food in her hand and her back to the ape. If the ape produced an auditory signal, the experimenter either turned to face the ape or, in the control condition, away from the ape. We found that condition had no significant effect on whether the apes followed their initial auditory signal with a visual signal. Furthermore, the apes did not show greater persistence with, or elaboration of, their auditory signals when the human did not turn to face them, than when she did. In contrast, the apes showed significantly more persistence and elaboration of visual signals when the experimenter turned to face them. Our results suggest that while the orangutans and gorillas were able to discriminate human visual attention and use visual gestures accordingly, they did not attempt to manipulate this attention through the use of auditory behaviors to initiate visual communication.