Recognition and processing of vocal signals in cotton -top tamarins (Saguinus oedipus)

All organisms that utilize a system of vocal communication to mediate behavioral interactions with conspecifics must evolve mechanisms to recognize conspecific vocal signals. In this thesis, I present three studies that examine how cotton-top tamarins recognize their species-typical combination long call (CLC). Upon hearing a CLC, tamarins often emit a CLC in response, a behavior known as antiphonal calling. All experiments reported in this thesis use tamarin's natural antiphonal calling response as the primary measure of recognition. In Study 1, I tested which acoustic features across the global structure of the call are important for recognizing CLCs. Results indicate that the two most important cues used for global CLC recognition are frequency contour and the temporal pattern of the syllables. Experiments in Study 2 examined whether tamarins can recognize individual syllables from CLCs independent of the global structure. Here data indicated that tamarins are sensitive the acoustic structure of individual syllables suggesting that each syllable may be represented independently. The final set of experiments addressed how the signal is processed by the recognition system. Results indicated that the system can extract the call from a high degree of noise and that the antiphonal response can be initiated from two different processing levels. The first level response after the signal is identified as a CLC, while the second level response integrates both CLC identification as well as the information content encoded in the signal. Overall, these data suggest that vocal signal recognition in tamarins involves several perceptual processes that detect and integrate acoustic cues before initiating the antiphonal response.