Czech linguist Nikola Paillereau on how babies learn multiple languages
“Well, it was my passion for the French language. I was really in love with French and started learning it when I was 11. Then, when I was 16, I met my future husband, who was French.
“So when I finished high school, I moved to France to do my university studies there and to live with my ex-husband. These are the three things that really led me to move to France, where I happily lived for many years.”
And do I understand it correctly that you raised bilingual children together?
“Yes. With my ex-husband, who is French, we raised our daughter to be bilingual — Czech and French. Well, now she is actually trilingual, but she was raised in a bilingual setting.”
So the fact that you raised a bilingual daughter — was that something that got you interested in researching bilingualism or bilingual children?
“Yes, of course. Having a bilingual, or now trilingual, daughter naturally made me interested in the topic. This is why I chose this field. About two and a half years ago, I decided to create a project focused on bilingualism.”
Bilingualism is widely regarded as something very positive. Are there any downsides that parents should know about?
“Well, it depends. You’re right that many parents see it as something positive, but some people also see it as negative. Some are afraid that raising a child in a bilingual setting will confuse them.
“This belief comes mainly from the fact that small children tend to mix languages. But the question is whether mixing languages — or code-switching — is unusual.
“If you look at bilingual adults, it is actually the norm. Many bilingual adults mix languages, and in some cultures, such as in Quebec or in Spanish-English communities in the US, code-switching is completely normal. So it should not be seen as a sign of confusion.
“When children are very young, around one or two, their vocabulary is limited. They simply use whatever words they know to be understood, so if they know words from two languages, they mix them. This is not confusion — it is pragmatism.
“Research also shows that already by the age of two, children can use the right language with the right parent, so even very young children can distinguish between their two languages.”
As you said, you started a project that focuses on how infants several months old perceive human speech. Can you take us through what the research looks like in everyday terms? What does a typical study look like?
“Yes, of course. I am actually not researching new-borns, because for that you would need to work directly in maternity wards, which is difficult.
“We found that both monolingual and bilingual infants can distinguish the two dialects —the Silesian dialect and standard Czech — at four months, but they use different strategies.”
“We study infants from four to twelve months of age, a period in which huge changes occur in speech perception. At the beginning, infants are very sensitive to subtle phonetic differences. For example, a Japanese infant can distinguish between the consonants l and r, while adult Japanese speakers no longer perceive the difference.
“By twelve months, infants focus only on contrasts that are functional in their native language and lose sensitivity to contrasts that do not exist in their mother tongue.
“In my research, we focus on two tasks. The first task examines whether infants can hear a Czech contrast between a short vowel “a” and a long vowel “á”, and how sensitivity develops between four and twelve months. We also test bilingual infants, because not all languages have vowel-length distinctions.
“We also play them foreign contrasts, such as a Swedish vowel contrast that is very subtle to Czech ears but clear to Swedish speakers. We want to know until when infants remain sensitive to it.
“The second task examines whether infants can distinguish between two dialects of their native language — the Silesian dialect and Standard Czech — at four months, and how this discrimination develops during the first year of life, including differences between monolinguals and bilinguals.”
I know the research is ongoing, but can children distinguish the difference between the dialects?
“Yes, the research is ongoing, mainly because we are still collecting data from bilingual infants. We already have enough monolingual data and recently presented interim results at a major conference on child language in Boston.
“We found that both monolingual and bilingual infants can distinguish the two dialects at four months, but they use different strategies.
“Monolingual infants prefer the familiar dialect — Standard Czech — at four months, but this preference switches to the unfamiliar dialect at six months.
“Bilingual infants, however, do not show the same preference for the familiar dialect at four months, possibly because they are used to hearing different languages, so neither dialect surprises them.”
Concerning the research on bilingual families, does it matter what the second language is, or can any bilingual family take part?
“Yes, it matters. Families must expose their infants to Czech, and the second language must be one that does not have vowel-length distinctions.
“We want to see whether bilingual infants acquire the Czech vowel-length contrast later than monolingual infants, who hear this contrast all the time, while bilingual infants hear it less because the other parent does not produce it.”
Children can understand a language before they speak it. At around what age do they really understand what is being said, and can you monitor that in your study?
“Yes, definitely. Research shows that infants start understanding words at around six months of age, especially words for body parts or food items — things they can easily see or experience.
“By one year, they may start producing words, but they understand them earlier, as you said.
“We can test this using behavioural methods. For example, I conducted a study with an eye tracker. The baby sits on a parent’s lap in front of a monitor showing two pictures — say, a banana and a yogurt. Then they hear: ‘Oh, look, look at the banana.’
“The eye tracker monitors the baby’s gaze. We can then analyse whether the baby looks at the correct image and determine which words they understand.”
What about babbling? Do children babble differently depending on what language they hear?
“This is a very interesting question and one that I ask in my project. Besides studying perception, we also study infants’ speech production — how they babble.
“Based on very limited previous research, bilingual infants seem to start babbling differently to each parent at around eleven months.”
“We have monolingual and bilingual babies, and we record them monthly while they babble with their mother and father. We want to know at what age they start babbling differently depending on the parent.
“We do not have the answer yet because analysing production data takes a long time — we may need two more years.
“But based on very limited previous research — only about six studies — bilingual infants seem to start babbling differently to each parent at around eleven months.
“It is fascinating to imagine that even babbling can differ depending on the language of the parent.”
Some parents are afraid of raising children in a bilingual setting. Experts often recommend the one-parent-one-language approach. Is this something you recommend?
“This method was developed about 100 years ago, but today we consider it just one possible approach.
“What matters most is providing enough input. For example, in the Czech context, mothers often stay home with infants, so the child hears a lot of Czech. If the father works long hours and only spends one or two hours a day with the child, the child gets far less exposure to the father’s language.
“In such cases, it may help if both parents speak the father’s language during weekends so the child gets enough exposure.
“The quality of input is also important. Putting a child in front of a TV is not sufficient. In order to achieve a high mastery of the language, the child needs to learn through social interaction.
“Environment and motivation also matter. Children want to be understood, and that motivates them to use both languages.”
The research is taking place mostly in your laboratory called LemonLab. I know it stands for Language and Emotion. Why ‘emotion’?
“In our research group, we also study how children acquire emotional vocabulary. One of my students will do her PhD on this topic.
“We want to monitor when infants master emotion words and ideally develop a screening tool to check whether children develop according to typical norms.
“If we find children who know fewer emotion words than expected, it might indicate a risk of disorders such as autism spectrum disorder, so this tool could help identify such cases early.”
How long will the research continue, and what will be the final outcome?
“We started two years ago. This project is unusual because most Czech grants last three years, while this one lasts five. It is a special grant intended for people who studied and completed their PhD abroad. So the project will continue for three more years.”
Is there anything else you would like to add that I haven’t asked?
“Yes. As I mentioned, we are still looking for bilingual families. If any listeners have babies and would like to participate, they are very welcome.
“You can visit our website, lemonlab.cz, and enrol in the research. We also offer interesting programs for families, including monthly meetings where we discuss topics such as psychomotor development and language development.
“We also do practical activities — exercises, yoga, and more. So you are very welcome to join our research project and become part of our community!”
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