Discrimination of chirp vocalizations in the cotton-top tamarin

Natural exemplars of two types of chirp vocalizations were presented to eight groups of cotton-top tamarins (Saguinus o. oedipus) in a playback paradigm. The two chirps share many acoustic features in common but are used in entirely different circumstances. The tamarins gave different vocal and behavioral responses to the playbacks of each chirp type, indicating that a discrimination was made. The results suggest that tamarins can discriminate subtle acoustic cues which have communicative significance. In the absence of the nonvocal cues and social contexts that normally co-occur with these vocalizations the tamarins responded with the same vocal responses they would have given in normal social contexts. Significant differences in post-stimulus behavior to the two types of stimuli appeared in the first two blocks of trials, indicating that the playback paradigm can be an efficient means of testing discrimination between different call types.