Psychophysical basis for finite-state song syntax in Bengalese finches

Abstract

Bengalese finches have been domesticated for 250 years in Japan from wild white-rumped munias originally imported from China. Bengalese finches were domesticated for parental behavior and white color morphs, but not for songs. Nevertheless, Bengalese finches sing complex songs: 2-5 song notes were chunked and chunks are organized into finite-state syntax. Song duration indicates physical fitness of the bird and song complexity stimulates female reproductive behavior. We examined sequential expertizes in Bengalese finches using behavioral procedures. In a click detection task, birds were trained to peck when they heard a short click embedded in a chunk or between chunks. Reaction times were longer in the former cases. In a flash-song interruption task, song termination occurred more often when the flash was given between chunks. These data are suggestive of the perceptual and motor reality of chunk structures. In a serial reaction time task, birds where trained to peck horizontally arranged keys in certain order. Male birds learned the task better than females, suggesting that song motor control capacity may be utilized other motor domains as well. However, abstract rule learning by auditory discrimination was not possible, suggesting that the sequential expertizes maybe limited on the motor domain.