Zebra finches (Taeniopygia guttata) demonstrate cognitive flexibility in using phonology and sequence of syllables in auditory discrimination

Abstract

Zebra fnches rely mainly on syllable phonology rather than on syllable sequence when they discriminate between two songs. However, they can also learn to discriminate two strings containing the same set of syllables by their sequence. How learning about the phonological characteristics of syllables and their sequence relate to each other and to the composition of the stimuli is still an open question. We compared whether and how the zebra fnches’ relative sensitivity for syllable phonology and syllable sequence depends on the diferences between syllable strings. Two groups of zebra fnches were trained in a Go-Left/Go-Right task to discriminate either between two strings in which each string contained a unique set of song syllables (‘Diferent-syllables group’) or two strings in which both strings contained the same set of syllables, but in a diferent sequential order (‘Same-syllables group’). We assessed to what extent the birds in the two experimental groups attend to the spectral characteristics and the sequence of the syllables by measuring the responses to test strings consisting of spectral modifcations or sequence changes. Our results showed no diference in the number of trials needed to discriminate strings consisting of either diferent or identical sets of syllables. Both experimental groups attended to changes in spectral features in a similar way, but the group for which both training strings consisted of the same set of syllables responded more strongly to changes in sequence than the group for which the training strings consisted of diferent sets of syllables. This outcome suggests the presence of an additional learning process to learn about syllable sequence when learning about syllable phonology is not sufcient to discriminate two strings. Our study thus demonstrates that the relative importance of syllable phonology and sequence depends on how these features vary among stimuli. This indicates cognitive fexibility in the acoustic features that songbirds might use in their song recognition.