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

Abstract

Zebra finches 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 finches’ relative sensitivity for syllable phonology and syllable sequence depends on the differences between syllable strings. Two groups of zebra finches 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 (‘Different-syllables group’) or two strings in which both strings contained the same set of syllables, but in a different 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 modifications or sequence changes. Our results showed no difference in the number of trials needed to discriminate strings consisting of either different 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 different 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 sufficient 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 flexibility in the acoustic features that songbirds might use in their song recognition.

Temporal variability enhances the acquisition of stereotyped communication signals

“…In summary, our findings reveal that the temporal organization of acoustic elements can affect vocal learning in novel ways. In contrast to previous studies describing that syllable timing and sequencing have negligible effects on auditory perception (Lawson et al, 2018;Kriengwatana et al 2016;Fishbein et al, 2019;Geberzahn and Deregnaucourt, 2020), our expansive study emphasizes that temporal organization can modulate the strength of vocal learning and is consistent with studies highlighting a significant contribution of syllable timing and sequencing to sensory and sensorimotor processes across vertebrate taxa (Bee and Klump, 2005;Verzijden et al, 2007;van Heijningen et al 2013;ten Cate 2015, 2017;Benichov et al, 2016;Spierings and ten Cate 2016;Knowles et al 2018;Santolin and Saffran, 2018;Rouse et al, 2021;Mol et al, 2021;Ning et al,. 2023).…”

“The song remains the same”: not really! Vocal flexibility in the song of the indris

“…Terleph and colleagues proposed that, for turn-taking to occur effectively, males would be the ones adjusting their song to their mate’s one because of females’ noticeable variation in spectral and temporal characteristics of their phrases (Terleph et al 2018 ). Our results did not corroborate the pattern suggested by Terleph and colleagues ( 2018 ) but are in line with previous findings on Northern white-cheeked ( Nomascus leucogenys , Deputte 1982 ), agile ( Hylobates agilis, Koda et al 2013 ), white-handed gibbon ( Hylobates lar, Raimondi et al 2023 ) and indri (Torti et al 2017 ; De Gregorio et al 2019a , b ). In indris, the dominant pair generally orchestrates the overall architecture of the duet: the duet between the reproductive pair is the most common type of singing organization (De Gregorio et al 2022a , b ), only occasionally succeeded by non-dominants, consisting of the offspring, and shows longer durations and higher degrees of overlap (Gamba et al 2016 ).…”

“…If we narrow our focus to communicative signals, numerous animal species exhibit flexible behaviors that suggest a certain degree of plasticity in vocal communication (Bouchet et al 2016). For instance, certain bird species incorporate novel elements into their songs, adding new notes or rearranging existing sequences (white-crowned sparrow: Nelson et al 2004; zebra finches: Lipkind et al 2017;Ning et al 2023; for a review, see Williams 2004). Marine mammals such as dolphins and whales also exhibit individual variation in their vocalizations, suggesting the presence of flexible vocal repertoires in the foraging context (killer whales: Hill et al 2022) and in captive test sessions (Atlantic bottlenose dolphins: Eskelinen et al 2016;Kuczaj and Eskelinen 2014).…”