The vocal communication of non-human primates appears to havesome commonalities with human speech. Here, to investigate linguisticabilities in non-human primates, two preliminary experimentswere carried out by using a common marmoset (Callithrix jacchus).In Exp. 1, the marmoset was trained to discriminate pulse trains ofeither 0.5 or 2kHz frequencies that were repeated with intervals ofeither 50 or 200ms. Consequently, the marmoset successfully identifiedthe target train out of four stimuli. In Exp. 2, the marmoset wastrained to discriminate patterned repetition of A (0.5kHz, 50ms) and B(2kHz, 200ms) elements arranged into ABAB and AABB sequenceson absolute and relative discrimination procedures. Duringthe absolute discrimination training, the ABAB and AABB sequenceswere presented for positive and negative trials, respectively. Duringthe relative discrimination training, there was a transition fromthe AABB to the ABAB sequences during the positive trials whileonly the AABB sequence was presented in the negative trials. Consequently,the marmoset could achieve relative discrimination butfailed at absolute discrimination. These findings imply that the marmoset'sability to process auditory signals is sufficient for the memoryof physical properties of sounds and the online segmentation of anauditory stream but is not sufficient to build a representation of anauditory sequence in long-term memory. Such restricted ability ofauditory sequence processing may be due to a less developed language-related brain structures in non-human primates.
|
