The World Until Yesterday: What Can We Learn from Traditional Societies? (68 page)

In short, bilingual or multilingual people have constant unconscious practice in using executive control. They are forced to practise it whenever they speak, think, or listen to other people talking—i.e., constantly throughout their waking hours. In sports, art performance, and other arenas of life, we know that skills improve with practice. But: which are the skills that practice of bilingualism improves? Does bilingualism merely develop bilinguals’ specific skill at switching between languages, or is bilingualism more generally useful to them?

Recent studies have devised tests to explore this question by comparing problem-solving by bilingual and monolingual people ranging from
3-year-old children to 80-year-old adults. The overall conclusion is that bilinguals of all those ages have an advantage at solving only a specific type of problem. But it is a broad specific problem: solving tasks that are confusing because the rules of the task change unpredictably, or because there are misleading and irrelevant but glaringly obvious cues that must be ignored. For instance, children are shown a series of cards depicting either a rabbit or a boat that is either red or blue, and that does or doesn’t have a gold star. If a gold star is present, children must remember to sort the cards by color; if a gold star is absent, they must remember to sort the cards by the object depicted. Monolingual and bilingual subjects are equally successful at such games as long as the rule remains the same from trial to trial (e.g., “sort by color”), but monolinguals have much more difficulty than bilinguals at accommodating to a switch in rules.

As another example of a test, children sit in front of a computer screen on which either a red square suddenly flashes on the left of the screen or else a blue square flashes on the right of the screen. The keyboard below the screen includes a red key and also a blue key, and the child must push the key with the same color as the flashing square. If the red key is on the left of the keyboard and the blue key is on the right—i.e., in the same relative position as the flashing square of the same color on the screen—then bilinguals and monolinguals perform equally well. But if the positions of the red and blue keys are reversed to create confusion—i.e., if the red key is on the left side of the keyboard but the blue flashing square is the one on the left side of the screen—then bilinguals perform better than monolinguals.

It was initially expected that this advantage of bilinguals at tests involving rule changes or confusing information would apply only to tasks involving verbal cues. However, the advantage proves to be broader, and to apply also to non-verbal cues of space, color, and quantity (as in the two examples that I just described). But this hardly means that bilinguals are better than monolinguals at everything: the two groups tend to perform equally well at tasks without rule changes to be attended to, and without misleading cues to be ignored. Nevertheless, life is full of misleading information and changing rules. If bilinguals’ advantage over monolinguals in these trivial games also applies to the abundance of confusing or shifting real-life situations, that would mean a significant advantage for bilinguals.

One interesting recent extension of these comparative tests is to infants. One might imagine that it would be meaningless or impossible to test “bilingual infants”: infants can’t speak at all, they can’t be described as bilingual or monolingual, and they can’t be asked to perform tests by sorting cards and pushing keys. In fact, infants develop the ability to discriminate speech that they hear long before they can speak themselves. One can test their powers of discrimination by watching whether they can learn to orient differently to two different sounds. It turns out that newborn infants, who have had no exposure to any of the world’s languages, can discriminate between many consonant and vowel distinctions used in one or another of the world’s languages, whether or not it happens to be their “native” language (which they haven’t heard except from inside the womb). Over the course of their first year of life, as they hear speech around them, they lose that initial ability of theirs to discriminate non-native distinctions that they aren’t hearing around them, and they sharpen their ability to discriminate native distinctions. For instance, the English language discriminates between the two liquid consonants
l
and
r
, while the Japanese language doesn’t; that’s why native Japanese people speaking English sound to native English-speakers as if they are mispronouncing “lots of luck” as “rots of ruck.” Conversely, the Japanese language discriminates between short and long vowels, while the English language doesn’t. However, newborn Japanese infants can discriminate between
l
and
r
, and newborn English infants can discriminate between short and long vowels, but each loses that ability over the first year of life because the distinction carries no meaning.

Recent studies have concerned so-called crib bilinguals: i.e., infants whose mother and father differ from each other in native language, but whose mother and father have both decided to speak her or his own language to the infant already from day 1, so that the infant grows up hearing two languages rather than just one language. Do crib bilinguals already gain over monolinguals the advantage in executive function, enabling them to deal better with rule switches and confusing information, that is apparent after the child can actually speak? And how does one test executive function in a pre-verbal infant?

A recent ingenious study by the scientists Ágnes Kovács and Jacques Mehler, carried out in the Italian city of Trieste, compared seven-month
“monolingual” infants with infants “bilingual” in Italian plus either Slovenian, Spanish, English, Arabic, Danish, French, or Russian (i.e., hearing one language from their mother and the other language from their father). The infants were trained, conditioned, and rewarded for correct behavior by being shown a cute picture of a puppet popping up on the left side of a computer screen; the infants learned to look in the direction of the puppet and evidently enjoyed it. The test consisted of pronouncing to the infant a nonsense trisyllable with the structure AAB, ABA, or ABB (e.g.,
lo-lo-vu, lo-vu-lo, lo-vu-vu
). For only one of the three structures (e.g.,
lo-lo-vu
) did the puppet appear on the screen. Within 6 trials, on hearing
lo-lo-vu
both “monolingual” and “bilingual” infants learned to look towards the left side of the screen to anticipate the appearance of the cute puppet. Then the experimenter changed the rules and made the puppet appear on the right side (not on the left side) of the screen, in response not to the nonsense word
lo-lo-vu
but to
lo-vu-lo
. Within 6 trials, the “bilingual” infants had unlearned their previous lesson and had learned the new correct response, but the “monolingual” infants even after 10 trials were still looking at the now-wrong side of the screen on hearing the now-wrong nonsense word.

One can extrapolate from these results, and speculate that bilingual people may have an advantage over monolingual people in negotiating our confusing world of changing rules, and not merely in the trivial tasks of discriminating
lo-lo-vu
from
lo-vu-lo
. However, you readers will probably require evidence of more tangible benefits before you make the commitment to babble consistently in two different languages to your infant children and grandchildren. Hence you will be much more interested to learn about reported advantages of bilingualism at the opposite end of the lifespan: old age, when the devastating tragedy of Alzheimer’s disease and other senile dementias lies in store for so many of us.

Alzheimer’s disease is the commonest form of dementia of old age, affecting about 5% of people over the age of 75, and 17% of those over the age of 85. It begins with forgetfulness and a decline of short-term memory, and it proceeds irreversibly and incurably to death within about 5 to 10
years. The disease is associated with brain lesions, detectable by autopsy or (in life) by brain-imaging methods, including brain shrinkage and accumulation of specific proteins. All drug and vaccine treatments to date have failed. People with mentally and physically stimulating lives—more education, more complex jobs, stimulating social and leisure activities, and more physical exercise—suffer lower rates of dementia. However, the long latency period of up to 20 years between the beginning of protein build-up and the later appearance of Alzheimer’s symptoms raises questions of cause and effect about the interpretation of these findings concerning stimulating lives: does stimulation itself really decrease Alzheimer’s symptoms, or were those individuals instead able to lead stimulating lives precisely because they were not suffering from early stages of protein build-up, or because of genetic advantages that also protected them against Alzheimer’s disease? In the hope that stimulating lives might be a cause rather than a result of reduced disease processes, older people afraid of developing Alzheimer’s disease are sometimes urged to play bridge, play challenging online games, or solve Sudoku puzzles.

Intriguing results of the last few years suggest a protective effect of life-long bilingualism against Alzheimer’s symptoms. Among 400 patients studied at clinics in Toronto, Canada, mostly in their 70s, and with a probable diagnosis of Alzheimer’s disease (or other dementias in a few cases), bilingual patients showed their first symptoms at an age 4 or 5 years older than did monolingual patients. Life expectancy in Canada is 79, hence a delay of 4–5 years for people in their 70s translates into a 47% decrease of probability that they will develop Alzheimer’s symptoms at all before they die. The bilingual and monolingual patients were matched in occupational status, but the bilingual patients had received on the average
lower
(not higher) levels of education. Because education is associated with lower incidence of Alzheimer’s symptoms, this means that differences in education could not explain the lower incidence of symptoms in the bilingual patients: their lower incidence was
despite
their having received less education. A further intriguing finding was that, for a given level of cognitive impairment, bilingual patients had
more
brain atrophy revealed by brain-imaging methods than did monolingual patients. Expressing this differently, bilingual patients suffer less cognitive impairment
than do monolingual patients with the same degree of brain atrophy: bilingualism offers partial protection against the consequences of brain atrophy.

The protection afforded by bilingualism does not raise the same uncertainties of interpretation about cause versus effect raised by the apparent protection offered by education and stimulating social activities. The latter might be results rather than causes of early stages of Alzheimer’s lesions; and genetic factors predisposing one to seek education and social activities might also protect one against Alzheimer’s disease. But whether one becomes bilingual is determined in early childhood, decades before the earliest Alzheimer’s brain lesions develop, and regardless of one’s genes. Most bilingual people become bilingual not through any decision or genes of their own, but through the accident of growing up in a bilingual society, or of their parents emigrating from their native land to a land with a different language. Hence the reduced Alzheimer’s symptoms of bilinguals suggest that bilingualism itself protects against Alzheimer’s symptoms.

How might this be? A short answer is the aphorism “Use it or lose it.” Exercising most body systems improves their function; failing to exercise them lets their function deteriorate. This is the reason why athletes and artists practise. It’s also the reason why Alzheimer’s patients are encouraged to play bridge or online games, or to solve Sudoku puzzles. But bilingualism is the most constant practice possible for the brain. Whereas even a bridge or Sudoku fanatic can play bridge or solve Sudoku puzzles for only a fraction of a day, bilingual people impose extra exercise on their brain every second of their waking hours. Consciously or unconsciously, their brain is constantly having to decide, “Shall I speak, think, or interpret sounds spoken to me according to the arbitrary rules of language A, or of language B?”

Readers will share my personal interest in some unanswered but obvious further questions. If one extra language offers some protection, do two extra languages offer more protection? If so, does the protection increase in direct proportion to the number of languages, or else more steeply or less steeply? For instance, if bilingual people get four years of protection from their one extra language, does a New Guinean, an Aboriginal Australian, a Vaupés River Indian, or a Scandinavian shopkeeper speaking five languages (four beyond her first language) still get just 4
years of protection, or does she get 4 × 4 = 16 years of protection, or (if juggling four extra languages is much more than four times more taxing than juggling just one extra language) does she even get 50 years of protection? If you had the misfortune that your parents didn’t raise you as a crib bilingual, and that you didn’t learn a second language until you began high school at age 14, can you ever catch up to crib bilinguals in the benefits obtained? Both of these questions will be of theoretical interest to linguists, and of practical interest to parents wondering how best to raise their children. All of this suggests that bilingualism or multilingualism may bring big practical advantages to bilingual individuals, beyond the less practical advantages of a culturally enriched life, and regardless of whether language diversity is good or bad for the world as a whole.

The world’s 7,000 languages are enormously diverse in a wide range of respects. For instance, one day while I was surveying birds in jungle around Rotokas village in the mountains of the Pacific island of Bougainville, the villager guiding me and naming local birds for me in the Rotokas language suddenly exclaimed
“Kópipi!”
as he pointed out the most beautiful bird song that I had ever heard. It consisted of silver-clear whistled tones and trills, grouped in slowly rising phrases of two or three notes, each phrase different from the previous one, and producing an effect like one of Franz Schubert’s deceptively simple songs. The singer proved to be a species of long-legged short-winged warbler previously unknown to Western science.