A Linguistic Shift
Recent census data suggests a multilingual explosion in the United States: over twenty percent of U.S. residents are now multilingual, more than double the percentage of the ‘80s. Consulting the data, we may observe a robust upward trajectory:
It appears we are fast approaching a naturally multilingual United States. What’s more, the monolingual among us should be interested in pursuing bilingualism ourselves—in fact, I feel an obligation, as a future parent, to promote bilingualism in my children. Though there are undoubtedly social benefits, I’ll focus here purely on the cognitive benefits afforded bilingual children, from the strictly neuroscientific (executive functions and cognitive flexibility) to the linguistic, as well as ramifications of both.
Why Be Bilingual?
Better (Raw) Cognition
Better Linguistic Ability
Benefits of Starting Early
Better (Raw) Cognition
Perhaps the best-known cognitive effect of bilingualism is on abilities related to executive function. What is perhaps unintuitive—but also incredibly exciting—is that the benefits of bilingualism seem to be “domain-general”; in the words of Bialystok, “An important aspect of the bilingual advantage in executive control is that it is not confined to linguistic processing.” When Foy & Mann asked bi- and monolingual children to respond to one auditory cue while ignoring another, the bilingual cohort was both quicker and more accurate.
Curiously enough—in a result that has been replicated elsewhere—this advantage was only observed on a non-linguistic variant of the task, in which neither sound was a syllable, versus a linguistic variant, in which both sounds were.
Bilingualism during childhood has also been found to improve conflict resolution and working memory—in one study, bilingual five-year-olds performed comparably on a working-memory task to monolingual seven-year-olds. (Incidentally, working memory is a cornerstone of fluid intelligence, or “IQ”.)
Footnote:
In the least, the two measures correlate significantly (R2 ~0.6) across multiple IQ test modalities. And there are other reasons bilingualism’s benefits to problem-solving should not be easily discounted. In the first paper describing cognitive load (couched in a context of problem-solving), Weller lists attention as an important component of problem-solving ability—as is another beneficiary of bilingualism, cognitive flexibility (see, for example, tSNE inhibition of the mental-set effect boosting problem-solving ability).
To consider the impact of domain-general benefits to executive function, consider the effects of domain-general executive dysfunction: to sample just a few, decreased quality of life and even persistent criminality. A child’s executive functions (which span such skills as self-control, working memory, and planning) prepare them for life; if we can improve a child’s executive functions, we stand a chance of improving their life.
These effects of bilingualism have been documented at all ages, even in infants. However, they are not low-hanging fruit: a study of kindergarteners found that the executive-function advantages of native speakers were not shared by monolingual peers in an immersion program. (More on immersion programs later—they still hold promise!)
Better Linguistic Ability
Of course, there are also linguistic benefits of bilingualism—this is, perhaps, unsurprising.
The literature suggests a positive (if somewhat language-dependent) effect on morphological and syntactic awareness—for example, Davidson et. al. showed that bilingual children (Urdu/English) of multiple ages proved more capable of classifying sentences as grammatically in/correct, and Hirata-Edds observed a similar advantage in Cherokee/English bilinguals.
Interestingly enough, it does not appear that bilingualism aids phonological awareness, despite aiding non-linguistic auditory attention.
Footnote:
Per Loizou & Stewart, any advantage is “a function of the relative phonological complexity of the child's first and second language”: bilinguals benefit when the second is less complex than the first.
Benefits of Starting Early
It might be reasonable to ask: why should we feel a need to encourage multilingualism early? Why not wait until our children are older?
There are a few principled answers: first, troves of research suggest that children learn languages more easily than adults; and, second, the benefits of bilingualism stand a change of dovetailing with one of the most important cognitive experiences of childhood: school.
Footnote:
One argument too small to warrant its own section: if you start early enough, it won’t take much effort on the child’s part (and likely won’t draw any objections). If you’re merely angling for working-memory improvements, you’re better off with this than trying to force your nine-year-old to do N-backing exercises—which, incidentally and to me mind-blowingly, have less and less permanent of an effect!
Simultaneous >> Sequential
It’s apparent: early bilinguals fare better than late bloomers. Even if you don’t believe in the existence of a “critical period” for language acquisition (and you discount the effects of diminishing plasticity, for some reason), there is still evidence in favor of starting a child’s bilingual journey early.
The distinction is made in research between “simultaneous” and “sequential” bilinguals: those who acquire both language at once, or one after another (sometimes significantly later in life). In a review of relevant literature, Byers-Heinlein & Lew-Williams remark that simultaneous bilinguals enjoy “better accents, more diversified vocabulary, higher grammatical proficiency, and greater skill in real-time language processing.”
Syncing with School
What’s more: one of the most important factors in a child’s cognitive development is schooling. To consider just one lossy projection, it correlates with a significant and permanent increase in IQ. It is thus worthwhile to recontextualize known benefits of bilingualism with respect to how they might aid in a child’s education.
For example, enhanced literacy and attention no doubt make for a better student—in this way, we might impute from bilingualism further-reaching (if less obvious) effects on developing cognition.
In fact, Foy & Mann themselves remark, at the end of their study into nonlingual benefits of bilingualism, that “executive function skills associated with academic success may possibly be trained.” Cognitive dividends paid by childhood bi- or multilingualism can go on to reinforce the dividends paid by education, in a way that would not be possible (or at least not nearly as expedient) in adults.
Immersion Programs
Relatedly, perhaps the lowest-effort path to childhood multilingualism exists as a part of schooling: immersion programs.
Bialystok compared the performances of English monolinguals and those in a French immersion program over five years and observed a gradual emergence of significant advantages in (deep breath) the Wug test, verbal fluency, sentence judgement, vocabulary, and IQ (a whopping six-point difference, as measured by Raven’s matrices).
There is an interesting lesson in this work: immersion programs need time to work. As such, this could be taken as further support for an early start: the longer your child can develop their bi- or multilingualism, the more they stand to benefit.
In Closing
I hope I have convinced you, if you need convincing, of the importance of bi- or multilingualism in children (and in adults, though they fall beyond the scope of this post). I have certainly convinced myself.
I will make sure my kids are bilingual, because it seems to be one of the highest-impact way to boost their cognition, and because it will enrich their life experiences with the ability to connect to an entirely difference subspace of humanity—can help produce a better mind, with a better human attached.
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