Learning to sing a song

How do songbirds learn the complex task of singing a song? Prof. Hahnloser of the Institute of Neuroinformatics and colleagues have demonstrated that zebra finches do this by dividing the complex task up into several simpler tasks. What does this learning behavior teach us?

Learning a new song is for songbirds very similar to learning language for humans. The task requires birds to learn new sounds and place them in the correct order. These two variables that are dependent on each other constitute a quadratic assignment problem for which no efficient mathematical solution is known.

Hahnloser and colleagues wanted to know how birds compute this learning task. Their research shows that birds simplify the complicated quadratic problem to a linear assignment problem that is easier to tackle. Zebra finches learn new sounds (song syllables) by taking syllables they already know and adapt them to those they have to learn. During this learning phase, the sequence of the sounds often gets mixed up. The birds then arrange the newly-learned syllables into the correct order in the next learning phase.

Parallels to human learning strategies
“The zebra finches have evolved the strategy of dividing a task as complex as learning a new song into easy-to-manage parts,” says Hahnloser. “This allows them to expand their repertoire with minimal effort.” “Interestingly, the birds’ strategy closely resembles the best methods currently used in computer linguistics to compare documents,” says Hahnloser. These algorithms compare written documents by considering their words in their context but regardless of their exact order.

The research also helps to understand the way children learn a new language (for example, the nasal vowels or rolling of the R in French) by minimally adapting the sounds they already know, at first without considering the context of these sounds in the foreign language.

Songbirds work around computational complexity by learning song vocabulary independently of sequence. Lipkind D, Zai AT, Hanuschkin A, Marcus GF, Tchernichovski O, Hahnloser RHR. Nat Commun. 2017 Nov 1;8(1):1247. pdf

See also UZH News: How songbirds learn a new song