Auditory-visual crossmodal representations of species-specific vocalizations

Abstract

Understanding others' status is necessary to live in complex societies. Chimpanzees seem to use various cues such as facial expressions and vocalizations to understand others' status. Vocalizations of other individuals are particularly important to understand social events that are invisible. To respond adequately to other chimpanzees' vocalizations, vocal individuality is principal information. We previously examined vocal individual recognition using an auditory-visual matching-to-sample task in a captive chimpanzee (Kojima et al. 2003). The subject chimpanzee correctly selected the picture of the vocalizer in response to species-specific vocalizations (pant hoots, pant grunts, and screams). The chimpanzee seems to use crossmodal representations of vocalizations to perform the matching task. Savage-Rumbaugh et al. (1988) demonstrated that two chimpanzees and a bonobo perform symbolic crossmodal tasks using artificial symbol systems. Although the results suggest that these apes have symbolic representations, it is still unknown how these species represent species-specific communication signals.