Adopted children don't forget their mother tongue

15 February 2017

People who are adopted as babies do not forget their native language. Recent research by Radboud University, among others, shows that Korean adoptees learn Korean more easily at a later age. Even if they were only a few months old at adoption.

Language learning begins in the womb. In the last term of pregnancy, when hearing is fully developed, the fetus already hears its mother talking endlessly. The baby is especially sensitive to the rhythm of his mother tongue and recognizes it immediately after birth. A child only really starts experimenting with sound sequences such as dadadada when he is six months old, in the so-called babbling phase. Until then, listening is key.

This knowledge that a baby gains in the first months of its life is never lost. Mirjam Broersma of the Center for Language Studies in Nijmegen discovered this when she introduced 29 Korean adoptees in the Netherlands to their mother tongue. Together with colleagues from Australia and Korea, she published her results in Royal Society Open Science.

Subtle sound differences

With the exception of the control group, the participants in Broersma's study were born in Korea. They were adopted at a very young age by Dutch-speaking parents. Half of them were younger than six months at the time of adoption, the other half were older than seventeen months (but younger than six years). During the study, the participants were between 23 and 41 years old. The people in the control group were born and raised Dutch people of about the same age as the people in the adoption group. They were also comparable in other respects, such as educational level and number of times they had visited Korea.

For two weeks they studied Korean sounds recorded by native speakers of Korea. The sounds they learned may look very similar to outsiders, but they do have a difference in meaning in Korean. An example is the word tal, which can mean 'daughter', 'moon' and 'mask' due to a varying pronunciation of the t. For non-Koreans, this difference in pronunciation is very subtle and difficult to learn. Although the adoptees, like the non-adopted, had difficulty distinguishing the sound differences, they picked them up more quickly.

Mother tongue speakers

At the beginning of the training period, the subjects also had to pronounce a list of Korean words themselves. At the end of the training, the same 'production task' was repeated one more time. The pronunciation was recorded and assessed by thirty native speakers from Hanyang University in Seoul. On the first production task, the adoptive group scored approximately equal to the control group. But on the second production task, after the training period, the mean score in the adoptive group was significantly higher. Their pronunciation was found to be better by native Korean speakers.

The differences between the adoptive group and the control group were clear. The first group was not only faster in distinguishing the sound differences, but their homemade sounds were also more easily identified and judged by the native speakers. Most fascinating, however, is the fact that Broersma found no difference between the early and late adoption groups. "Both groups of adoptees do equally well in pronunciation decades later, they are all much better than the control group," said the researcher.

unconscious memory

Broersma suspects that the results of her research apply to adopted children in general. Adoptees with a different language background probably also have an advantage if they start learning their native language at a later age. That is nice, because it makes it easier to make contact with the people and culture of their native country. Something that many adoptees need later in life. Broersma explains: “The mother tongue has disappeared from their conscious memory, but the knowledge in their unconscious memory reappears through our study.”

Within linguistics, this research has provided an important piece of new insight. It was known that language development starts very early, even in the womb. Until now, however, it was not known to what extent this knowledge is preserved even if the language is no longer offered, such as with adoption. It now appears that this very first knowledge is not lost, and can come in handy later on.