Effects of metronomic sounds on a self-paced tapping task in budgerigars and humans

The origin of rhythmic synchronisation or entrainment to a musical beat in animals have been widely discussed. Parrots are suitable animals to examine the relationship between the capability of vocal learning and spontaneous rhythmic synchronisation. In this study, budgerigars (Melopsittacus undulatus) learned to tap (peck) two keys alternately at a self-paced rate. Then, the metronomic sounds were played in the background during test sessions while the birds were performing the key pecking task, although they were not required to synchronise tap timing with the metronome. We found modest but significant effects of the metronome rhythms on the tap timing in some subjects. We also tested humans (Homo sapiens) using almost the same method. In contrast to the birds, a number of human subjects synchronised tap timing to the onset of the metronome without verbal or documented instructions. However, we failed to find an effect of the metronome on self-paced tap timing in some human subjects, although they were capable of rhythmic synchronisation. This is the first report describing the effects of metronomic sounds on self-paced tapping in non-human vocal learners. This study introduces a new method that can be used in future research comparing birds that differ in vocal learning capacities, social structure, age, sex, hormonal status, and so on as part of examinations of the evolutionary foundations of beat processing.