Language learning very early on in life can be subconsciously retained even when no conscious knowledge of the early experience remains, researchers said.
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.
The experiment involved 29 Korean-born Dutch speakers and an equal-sized native Dutch-speaking control group.
More From This Section
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.
"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.
The study was published in the journal Royal Society Open Science.