Matching vocalizations to vocalizing faces in a chimpanzee (Pan troglodytes)

Auditory-visual processing of species-specific vocalizations was investigated in a female chimpanzee named Pan. The basic task was auditory-visual matching-to-sample, where Pan was required to choose the vocalizer from two test movies in response to a chimpanzee's vocalization. In experiment 1, movies of vocalizing and silent faces were paired as the test movies. The results revealed that Pan recognized the status of other chimpanzees whether they vocalized or not. In experiment 2, two different types of vocalizing faces of an identical individual were prepared as the test movies. Pan recognized the correspondence between vocalization types and faces. These results suggested that chimpanzees possess cross-modal representations of their vocalizations, as do humans. Together with the ability of vocal individual recognition, this ability might reflect chimpanzees' profound understanding of the status of other individuals.