The bilingual edge: what the research says

15 min readApr 30, 2024


A street in Sydney’s Chinatown (Photo: Jordanopia/Wikimedia Commons)

This is a transcript of a Subtitle podcast episode.

Patrick Cox: When Bob Dole was campaigning for the Presidency against Bill Clinton– this is back in the mid 1990s– he said this:

“​​If we want to ensure that all of our children had the same opportunities — yours, mine, everyone’s — in America, alternative language education should stop.”

Patrick Cox: He was talking about bilingual education. Specifically — mainly — Spanish-speaking kids taking math and history and other classes in Spanish. He wanted everyone to learn English, learn IN English so that they’d be able to one day speak English well. And he was talking about this maybe because he believed it but also because it was a popular opinion.

Patrick Cox: From Quiet Juice and the Linguistic Society of America, this is Subtitle: stories about languages and the people who speak them. I’m Patrick Cox.

There’s a ton of research about bilingualism. You can find studies about bilingual baby talk; about speaking in different registers; about how we think in different languages — or think we think; about how we learn, how we function. how we age. It’s exhausting! So for this episode, we’re going to hear about research in two subject areas: bilingual education, always a topic of disagreement. And before that, language acquisition. The language or languages you learn from the start of your life.

Here’s a study published in 2022, out of the University of Texas. Three hundred infants are tested on various tasks. The bilingual babies among them perform the tasks more efficiently than their monolingual counterparts. These infants are aged between 6 and 10 months old. Wow.

Ari Daniel: I can beat that Patrick, I can go much younger.

Patrick Cox: This is Ari Daniel. He’s a science reporter with NPR. And you may have heard him on other episodes of Subtitle. He says researchers are now studying bilingualism from the very beginnings of language acquisition.

Ari Daniel: It actually starts way earlier than we ever thought. Researchers are learning more by looking not just at the sounds we make, but at a language is rhythm and pitch as well. Okay, so, Patrick, I want you to go back to when you were a kid and listen to this.

Theme tune to TV show, Neighbours

Patrick Cox: Yes, I recognize that. I don’t think American listeners will. Because this is an Australian soap, right? Neighbours. It played in the United Kingdom. I don’t think it ever played over here. Not one of my favorites, I have to say.

Ari Daniel: In the late Eighties, a British psychologist published a study showing that pregnant moms who watch Neighbours every day gave birth to babies who reacted more strongly to the theme song than those whose moms didn’t watch the show.

Eino Partanen: That is the first paper which has shown that fetuses can be exposed to a specific type of sound and then elicit some sort of reaction to them after they’ve had been born.

Ari Daniel: Eino Partanen is a Finnish neuroscientist at Aarhus University Hospital in Denmark. [He is now at the University of Helsinki.] Partanen wasn’t involved in the soap opera study, but it’s inspired a bunch of his work, including a cool thing he and his colleagues tried a few years ago while in Finland. They took a group of pregnant moms and for 15 minutes a day, five days a week during their last trimester, he asked them to play this loud.

Sound of a digital-sounding voice:“Ta ta ta.”

Ari Daniel: Wow. That doesn’t sound like Finnish music hit.

Eino Partanen: No, sadly. Even for Finns that would be annoying.

Ari Daniel: How do you find moms that want to do that?

Eino Partanen: Through friends and relatives who don’t dare to say “no,” mostly.

Ari Daniel: Plus through internet discussion boards. Occasionally in the recording the middle syllable of the “Ta ta ta” sequence would be swapped out for a different vowel.

Sound of a digital-sounding voice:“Ta ta ta. Ta to ta. Ta ta ta. Ta to ta.”

Patrick Cox: Really Ari? Is there a difference there?

Ari Daniel: Yeah, it goes, “Ta ta ta. Ta to ta.” Listen one more time.

Sound of a digital-sounding voice:“Ta ta ta. Ta to ta. Ta ta ta. Ta to ta.”

Patrick Cox: Okay, I hear that but it’s really subtle, just the middle syllable, right?

Ari Daniel: Right. And Partanen did one other thing with the middle syllable. Sometimes he changed its pitch.

Sound of a digital-sounding voice: “Ta ta ta. Ta [different pitch] ta ta. Ta ta ta. Ta [different pitch]ta ta.”

Ari Daniel: And then just days after they were born, Partanen played the stimuli to the newborns and used an EEG to monitor their brain activity. He compared it to a group of newborns who didn’t receive the in utero “Ta ta ta” stimulation. The results couldn’t be clearer. Both groups of babies responded identically to the sequence with the different vowel because that second vowel is heard all the time in Finnish — you don’t need a special recording to be exposed to it as a fetus. But only the babies who had been exposed in utero to the pitch change recognized it once they’re born. And that’s because just as an English pitch isn’t relevant in Finnish, compared to some languages, Chinese for example, where words take on different meanings based on pitch. So babies that don’t hear different pitches in utero don’t respond to them later. Or more simply, babies respond to the signals they first hear in utero. And of course, these signals can come from one language or many languages.

Eino Partanen: The way I think of the early development is the fetal stage builds up specific predispositions to what we’re going to experience later on after we’ve been born. Babies aren’t born as a blank slate.

Ari Daniel: Rather, a kind of groundwork gets laid in utero, that familiarizes us with the world we’re about to encounter. And if that world has more than one language, we also prep for that in utero.

Janet Werker: A lot of language crosses the uterine wall, and so by the time a baby is born, they’re not an inexperienced listener.

Ari Daniel: Janet Werker is a developmental psychologist at the University of British Columbia in Vancouver.

Janet Werker: It’s a very multilingual city. We have babies growing up in all sorts of combinations of languages.

Ari Daniel: Including bilingual homes where English and Filipino are spoken — two languages with different spoken rhythms. And Werker wanted to know whether babies exposed to English and Filipino in utero are familiar with both languages at birth, and whether they can differentiate between them. She and her colleagues worked with newborns several hours to several days old. Granted, it’s a tricky population.

Janet Werker: They don’t talk yet. They don’t point. They don’t follow instructions.

Ari Daniel: So she wired a pressure sensor up to a pacifier.

Janet Werker: Babies will change their rate of sucking, their strength of sucking — and you can condition the sucking reflex.

Ari Daniel: Which is to say that how much a baby sucks or how strongly that baby sucks can tell you how familiar and interesting something is to the baby. Like these muffled speech samples that Werker played, filtered to sound like they would in the womb.

Sound of muffled voice

Ari Daniel: This is English. And this is Filipino.

Sound of muffled voice

Ari Daniel: The results.

Janet Werker: From the moment a newborn baby is born, who is growing up in a bilingual environment, they listen preferentially to speakers have either of the languages they heard in utero. And they’re able to track the rhythmical properties of each. So they’re born ready to learn two languages and not confuse them.

Ari Daniel: Werker says all this learning before birth might be useful. First, it may allow babies to identify who’s part of their community once they’re born. And second, just from rhythm cues, babies may be able to track how certain words function and give them a head start on learning that language. All this might come in handy when considering early interventions for things like dyslexia. These are still hypotheses, so Werker appreciates a more concrete and intimate lesson, one she’s learned by watching the parents watching their babies in an experiment like this.

Janet Werker: It communicates to the parent that their baby is interested in the world around them and is interested in learning from the first moments of life. And we’d like to think that this might make them treat their baby as the curious, involved little being that they are.

Patrick Cox: Okay, I get it. Newborns, they may seem kind of unformed. They can’t do very much. But don’t be fooled: There’s a ton going on.

Ari Daniel: And even before that, even before they’re born, language is such an irresistible force to us. It finds its way into the womb and it makes connections not just in the baby’s brain, but also between the baby inside and the world outside.

Patrick Cox: Yeah, and in one or several languages, right? And whether it’s one or more appears to really affect how the brain functions.

Ari Daniel: Yes.

Patrick Cox: Okay, Ari. So my kid who you’ve met and played charades with…

Ari Daniel: We had a a good time.

Patrick Cox …she’s bilingual, English and Chinese. Should I award myself a gold star for that? Does she have what some people call the bilingual edge?

Ari Daniel: You know, I asked Janet Werker about this in particular. And I said, “Does raising a kid in a bilingual environment, give that kid some advantage?” And she said that yes, there are certain advantages, like in the realm of what’s called executive function — the ability to switch between different tasks. But on the other hand, Janet Werker told me that often a bilingual kid will have a smaller vocabulary in each language than a monolingual kid, unless the bilingual kid is a really avid reader, and then they can kind of make up for it. So there are differences growing up monolingual versus bilingual. It’s not like one is better than the other. The key is that babies adapt to the language environment that they’re in, when they’re born and even before. So, doing well in the world really starts with doing well in the womb.

Patrick Cox: After the break. Ari Daniel is back with researchers looking into the contested area of bilingual education.

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Patrick Cox: Okay, bilingual education now. California is ground zero for this. In 1998 a group of Californians collected enough signatures to get a measure on the ballot, a measure that would almost completely outlaw bilingual education. The governor of California at the time was a Republican, and voters there had recently passed an anti-immigration ballot initiative. And now there was this ballot measure banning bilingual ed, which was kind of code for banning Spanish in schools. It passed.

Fast forward a couple of decades and the California legislature, now overwhelmingly Democratic with plenty of Latino representation– it decides that voters need to vote again on bilingual ed. So there’s a new measure which would essentially repeal that 1998 ban. It would reintroduce several different forms of bilingual ed back into California schools, And this measure, it also wins at the polls — and it wasn’t even close, 74 percent vote yes. And this repeal vote, a lot of people outside California missed this for understandable reasons– there was another result from that ballot hogging the headlines. Donald Trump was heading to the White House.

What changed Californians’ minds about bilingual education? Why such a dramatic reversal in such a short period of time, 18 years? There were the observations from teachers and other educators about what was working and what wasn’t, who was learning and who wasn’t, which students were dropping out. But more than that, there was the research. Not just research on babies and infants, but on older kids too. Research that continues to this day, and continues to reveal nuances that we weren’t clear about before. At the root, though, of all this is the same question, endlessly picked at by researchers. Does being bilingual carry an advantage?

Ari Daniel: And that question is, at least in the US the subject of a heated discussion.

Patrick Cox: I know when to hand back the reins to Ari Daniel.

Ari Daniel: It’s not a simple pro versus con debate, says Thomas Bak, a cognitive neuroscientist at the University of Edinburgh.

Thomas Bak: If we approach a topic as complex as bilingualism to believe that you can practically give a simple yes or no answer is, for me quite naive.

Ari Daniel: Let’s pull apart some of that complexity. A good starting place, says Judith Kroll, a psycholinguist at UC Riverside [She is now at UC Irvine] is to know that in the bilingual brain, both languages are active at all times, even when just one of those languages is being spoken.

Judith Kroll: Bilinguals develop exquisite control to be able to master and regulate the use of the two languages.

Ari Daniel: That control allows bilinguals to switch between their languages. Select one language while suppressing the other and focus on what they’re communicating in the moment.

Judith Kroll: The idea is that control isn’t necessarily limited to language itself, but may spill over into other domains of cognitive function.

Ari Daniel: Like ignoring irrelevant information and paying attention to what’s useful or juggling different tasks. And Thomas Bak says there may be big payoffs for bilinguals much later in life too.

Thomas Bak: I was involved in studies showing that people who speak more than one language have slower cognitive aging, have also four and a half years later onset of dementia and recover faster after stroke.

Ari Daniel: And some of these benefits may pertain not just to those who grew up bilingually, but also to those who learn another language as adults. These studies are part of a large body of work published over the last two decades that reveal the about-face in how we think about bilingualism in the United States. It used to be viewed with suspicion as an impediment to learning. Now it’s the opposite, where bilingualism is seen as beneficial to some degree — though, not by everyone.

Ken Paap: Yeah, I think it would be fair to say that I’m one of the leading skeptics.

Ari Daniel: Recently, Ken Papp, a cognitive psychologist at San Francisco State University, has been critiquing the studies demonstrating bilingual advantage. He argues that the control required to master and deploy two languages doesn’t necessarily transfer to other domains. He questions the demographics of the populations being tested. And he says that if researchers don’t detect a bilingual advantage in a particular study…

Ken Paap: They’re likely to just place the results of their study in their file drawer and never attempt to publish it. Likewise, reviewers and editors — their typical reaction is well that’s pretty boring, and those manuscripts are likely to be rejected.

Ari Daniel: Initially, Thomas Bak welcomed these criticisms.

Thomas Bak :Debate is healthy in science, it’s necessary.

Ari Daniel: But Bak says that he and other researchers have responded to Ken Paap with studies that have nipped his complaints in the bud. Still, Paap has persisted in vocalizing and publishing his same doubts. Bak says it’s time to move on. Yet perhaps not alone in his critique. Christiane Fellbaum, a computational linguist at Princeton, says there’s conflicting evidence when it comes to the studies examining bilingual advantage.

Christiane Fellbaum: Almost all experiments that I have seen, flawed.

Ari Daniel: Flawed, she says in a couple serious ways.

Christiane Fellbaum: The number of participants tends to be small. virtually no two bi- or multi-linguals have identical profiles. So as a consequence, it’s difficult — if not impossible — to set up a reproducible experiment.

Judith Kroll: It does seem to me that there are naysayers…

Ari Daniel: Psycholinguist Judith Kroll again.

Judith Kroll: …who are willing to take a couple of failures to replicate, to essentially destroy the entire field to dismiss all of the rest of the evidence.

Ari Daniel: To be fair, Fellbaum isn’t out to destroy the entire field. And she says bilingualism may indeed have some advantages. So does all this back and forth amount to anything more than academic infighting? Well, the answer to that question is something folks agree on.

Ken Paap: I think it’s the potential implications for public policy decisions that we make as a society.

Thomas Bak: Our science, it is done in a society we live in.

Ari Daniel: And this is where we get to the election in California. Ron Unz, a software developer and theoretical physicist by training was one of the chief organizers of an initiative passed in 1998 that made bilingual education programs in the state’s public schools a rarity.

Ron Unz: The way to make a child from that background bilingual is for the schools to teach them what they do not know, which is English. Then from the schools to just teach them what they already know, which is Spanish.

Patrick Cox: Wow, Ari, that is so interesting to hear Ron Unz now. I remember him back in 1998 when that first proposition was on the ballot. And his view — it seemed to be the majority view of Californians — was to get kids speaking and understanding English as quickly as possible. And that ballot proposition that he championed, voters overwhelmingly approved didn’t they?

Ari Daniel: That’s right 61 to 39%. And like you say, California was a different place then. There was still a lot of suspicion of bilingualism. And also there was this belief that kids shouldn’t be allowed to learn in their native language, that if they did they just wouldn’t learn English.

Patrick Cox: Right. So what has changed in the meantime?

Ari Daniel: Part of it is that there’s all this research that’s been done that I’ve been telling you about, that suggests a possible bilingual edge. And also California’s demographics have changed. It’s gotten even more multiethnic and more multilingual.

Patrick Cox: And what about the teaching methods? They’ve they’ve changed as well, right? I mean, there’s, there’s been this great rise in dual language immersion schools, where kids are taught whatever it is — math, science, history — in two languages in English for part of the day in the second language for the other part of the day. That must have had an effect too, isn’t it?

Ari Daniel: Right, because dual language programs in public schools tend to be very popular among parents. Many have really long waiting lists. And there are findings churned up by this discussion surrounding bilingual advantage. For example, researchers have found some evidence that bilinguals are better learners. Take a study that Thomas Bak conducted with a group of Scottish elementary schoolers. Most kids in Scotland learn in English only, as you probably know, Patrick, but a small number of them learn in both English and Scottish Gaelic.

Thomas Bak: Kids who are taught both in English and Gaelic are better in English spelling than kids that are only told in English. So kids who learn two languages, their English spelling gets better.

Ari Daniel: And Bak, who speaks seven languages, says the debate over bilingual education has little resonance in countries where speaking more than one language is unexceptional.

Thomas Bak: If we simply go across the world would find that in many countries bilingual education or a multilingual education is absolutely the norm with very good results.

Ari Daniel: Which brings us to an important point. The larger academic controversy over bilingual advantage occurs primarily in places where being monolingual is the norm. Like the US.

Thomas Bak: The biggest opposition come from countries where there is also a very strong, negative attitude to bilingualism in society: ingrained mistrust against anybody who speaks other languages on their own.

Ari Daniel: And this casts the opposition to bilingual education in a place like California in an unfortunate light, says Christiane Fellbaum.

Christiane Fellbaum: It comes down to anti foreign sentiment and perhaps even racism. It’s a very strong word, but I never use it to people are anxious about immigrants and there is a reasonably clearly defined target population.

Ari Daniel: Meaning the Latino community Ron Unz, the one who helped get the 1998 initiative passed, says that’s nonsense. So where does this leave us? Christiane Fellbaum for one, even with her reservations over the extent to which bilinguals are advantaged, she always offers couples who speak different languages the same piece of advice on how to raise their kids.

Christiane Fellbaum: I say, by all means, bring them up bilingually because your children will relate to both of your heritages and be able to look at the world with different perspectives.

Ari Daniel: And with that kind of openness, who knows? Maybe those kids will be the ones to resolve longstanding heated discussions.

Patrick Cox: After its 18 year ban, California is still playing catch-up when it comes to bilingual education. Since the lifting of the ban in 2016, many new dual language immersion programs have come into being, as well as other ways in which kids are learning in either their native tongue or a second language. But researchers say it’s simply too early to assess these programs, how effective they are. The pandemic, especially, has muddied the waters. So it’s going to be a while until we hear anything conclusive. Until then — and after then too — people will continue arguing about bilingual education. Yay!

Thanks to Ari Daniel. He’s a science reporter with NPR. If you haven’t heard it, check out his fabulous Subtitle episode from earlier in this season. It’s called “How the brain of an improv performer works.” Ari is also, as noted before a charades player, the world’s best.

Thanks also to Nina Porzucki, and to Allison Shao who writes the Subtitle newsletter and manages our social media accounts. And thanks to The World public radio program.

We’ll be back in a fortnight. I feel I can say fortnight in the US, at least now there’s a Taylor Swift song called Fortnight. Am I right? Thanks for listening.

Subtitle is a member of the Hub & Spoke audio collective.




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