People remember their birth language even if they have not had the chance to speak it, according to a new study.
The subconscious knowledge can then be tapped to speed up learning of the pronunciation of sounds of the lost tongue.
Scientists, including those from Radboud University in The Netherlands, found that decades after their adoption, Korean adoptees are better in pronouncing Korean sounds than control participants, even if they were only a few months old at the moment of their adoption.
Their results show that babies start with the learning and storing of speech sounds much earlier than was otherwise known.
The experiment involved 29 Korean-born Dutch speakers and an equal-sized native Dutch-speaking control group.
Throughout a two-week period of training, the adoptees were asked to identify three Korean consonants and then to try and reproduce them - the sounds were unlike anything in Dutch.
All of the spoken productions collected in the experiment were then rated by Korean listeners.
Adoptees' attempts at articulating the correct sound improved significantly more across the training period than control participants' scores, and, for adoptees only, the production success correlated significantly with rate of learning to identify the sounds, which also surpassed that of the controls.
"One of the most interesting findings was that no difference showed in the learning results of those Korean-born participants adopted under six months of age and those adopted after the age of seventeen months," said Mirjam Broersma, language scientist at Radboud University.
"This means that even in the very early months of life, useful language knowledge is laid down, and what has been retained about the birth language is abstract knowledge about what patterns are possible, not, for instance, words," said Broersma.
Significant learning occurs in the womb and first six months of life but up until now it was not clear what of that learning might be retained even without any further input in the language, and how it could be usefully called upon for language learning.
For people adopted internationally this is good news, especially as many of them try to reconnect with the people and culture of their birth countries.
The study was published in the journal Royal Society Open Science.
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