In search of the frontier between sound and language
Comparison between babies and song-birds when they are learning a non-existent language—a study of this kind has never been tried before. But this is what Claartje Levelt, Carel ten Cate (Leiden University) and Jelle Zuidema (University of Amsterdam) are attempting.
Why do only humans possess the capacity for language, and why does language have the structure it has? Possibly this is partly to be explained by the acquisition processes through which the mother tongue is learned. Various publications indicate that we can learn more about this learning process by studying the ways in which song-birds acquire sounds and tunes. Biologist Professor Carel ten Cate, PhD has spent many years studying zebra finches. Linguist Dr Claartje Levelt is investigating the language development of young children in Leiden’s “babylab”. Together with language theorist Dr Jelle Zuidema from the University of Amsterdam they are beginning, with support from NWO (Netherlands Organisation for Scientific Research), a comparative study of language acquisition in zebra finches and babies.
What exactly are you investigating?
Levelt: ‘Language, with its complex structure, is unique to humans. But the mechanisms by which language is learned appear to be common to other animals. Previous research has demonstrated this. We are now examining the frontier itself: where do these similarities end? Our approach consists of submitting babies and zebra finches to comparative experiments in acquiring an artificial language, and examining the extent to which they perceive the structure of those languages. Such a comparative investigation has never before been attempted.’ Ten Cate: ‘This is pure or basic research that can serve as the basis for further applied work. For example: with this knowledge we could eventually further help children who have difficulty with learning language.’
Why compare babies and zebra finches?
Ten Cate: ‘One can find parallels between the language acquisition process in babies and song-birds. Humans learn sounds, words and sentences. Songbirds learn sounds, strings made up of sounds, and eventually melodies in which the pieces are strung together.’ Levelt: ‘Six years ago Carel and I met at an academic gathering at Leiden University where the participants were investigating cognition. As a result we found a connection between both our areas of interest. Together with Jelle Zuidema we organised a conference on the subject, and that laid the foundation for our NWO-application, as a result of which, together with three PhD students, we have been able to start our research project.’
How do you carry out the research?
Levelt: ‘To begin with—and this is at once the biggest challenge—we have to develop experiments that demonstrate the similarities and differences between the learning process of babies and song-birds. What’s more, the experiments must be interchangeable between the two groups of ‘learners’. My group investigates the babies in the ‘babylab’. Jelle Zuidema’s group in Amsterdam is developing computer models that simulate the learning process of babies and zebra finches.’ Ten Cate: ‘In my group we study the zebra finches. We have already determined experimentally that zebra finches can recognise sound patterns. Now we have to examine the factors that contribute to whether or not zebra finches recognise such patterns.’ The research project of Levelt, Ten Cate and Zuidema will last for four years.