Auditory-visual intermodal recognition of human individuals by a chimpanzee

Kazuhide Hashiya

University of Tokyo, Japan

The ability of individual recognition is regarded as essential, especially for highly social and grouping animals. Among animals like passerine birds and primates, both visual and auditory signals appear to convey meaningful information about identity. However, most of these studies are limited to a single sensory modality and the correspondence between modalities are still unclear. How do animals recognize and integrate these separate and qualitatively distinct information from different sensory channels, for example, face and voice? This 'binding problem' is one of the unsolved questions in animal cognition (Hauser, 1996; Partan & Marler, 1999). I experimentally examined a human-raised chimpanzee's ability of individual recognition across visual and auditory modalities. The subject was a 14-year-old female chimpanzee. She had received long-term training of a computerized task to choose a picture from two alternatives corresponding to the sound previously presented (auditory-visual matching-to-sample task, AVMTS) (Hashiya & Kojima, 1997; Hashiya, in press). In the present experiment, recorded human voices and color portraits were newly introduced to examine the generalization of AVMTS performance. As results, the chimpanzee matched familiar human voices to the corresponding faces without particular training. This indicated that the chimpanzee naturally makes use of human vocal information in correspondence with the information from visual modality. The subject also matched unfamiliar individuals' voices and faces based on a form of reasoning: 'this voice should belong to this face, since it does not belong to the other face', that is, exclusion. And also, some of the differences that exist between the vocal signals of human females and males are naturally attributed to the different features in their faces, respectively. These suggest generality of the chimpanzee's recognition of auditory-visual intermodal relations beyond individuality and the ability of speaker identification.

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Partan, S., & Marler, P. (1999). Science, 283, 1272-1273.

Hashiya, K., & Kojima, S. (1997). Japanese Psychological Research, 39, 182-190.

Hashiya, K. (in press) Primate Research [Japanese with English Abstract], 15.

Hashiya, Kazuhide

Japan Society for the Promotion of Science and

Department of Speech and Cognitive Sciences, University of Tokyo

7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan