Published in the July/August edition of TableAUS, the magazine of Australian Mensa
The Joys of Bilingualism and How to Get There
I have the pleasure of teaching two adult classes in French. When other people find out this fact, their first question is, ‘Why would anyone learn another language?’ In fact, most of the class members ask the same question. Learning a language as an adult is a hard slog, and, at the rate of a lesson a week, is likely to take three years to be able to conduct a simple conversation. 
Sure, in a few months, I can give people the confidence to negotiate customs, direct a taxi driver, check in at the hotel and order a good wine, but the 4,000 words said to be needed to hold up one end of a conversation with their supporting grammar and non-verbal clues take longer. 
For older people, one obvious benefit of the process of learning a language is the delay of mental deterioration. One study showed that bilinguals with Alzheimer’s were diagnosed on average four years later than their monolingual peers. The mental agility required to learn a language evidently holds bilinguals in good stead.
New research suggests that people making decisions in their second language may be more objective than when they make similar decisions in their mother-tongue. These studies used standard tests requiring the participants to balance risks. In the mother tongue, people were more likely to avoid a possible 30% loss than make a possible 70% gain; in their second language, they could more easily see that the risk was the same in both cases. So bilinguals (may) make better investment decisions and relationship choices! 
Neuroscientists are surprised at the mental flexibility of bilinguals because not only do their brains have to store the vocabulary and grammar of both languages, when they speak, they activate both languages. This may explain why bilinguals may be slightly slower at recalling specific words in the language they are using, but it also reveals the benefit of more flexible thinking.
When we lived in multilingual Mauritius, we were amused at the strategy Mauritians used when they couldn’t recall a word: they simply switched over to the other language.
Some linguists believe that a second language gives the speaker a different framework for understanding the world. The scholars Sapir and Whorf in the early 20th Century proposed that the language you speak forces you into the worldview of that culture and language. This hypothesis is controversial, not least because it is hard to test.
Scholars have tried to devise conclusive tests.
For example, the range of words for colour differs in different languages. English, for example, makes a distinction between blue and green, and we can pick these colours when we see them. In some languages, there is only word for what English regards as two colours and speakers of those languages make no distinction between blue and green objects. Researchers believe that this means they may not see the difference.
Most linguists today accept a weak version of the Sapir-Whorf hypothesis: the language you are speaking has some influence on your world-view. As a bilingual, I cannot judge how much I am influenced by the world-views of French and English as I use them, but I observe that the French language forces you into expressions which have different implications in each language. For example, when in English I say, ‘We must’ in French I would say ‘Il faut’. This literally means ‘it is necessary’, and I speculate on how much French takes away personal responsibility by using the more impersonal turn of phrase.
At a lighter level, idioms in different languages reveal the way we think about each other. In French, the English expression ‘to take French leave’ is ‘filer à l’anglaise’ (slip away in the English manner)! The claim that French idioms are more logical than their English counterparts is borne out by the French version of ‘I read it in black and white’ – ‘Je l’ai lu en noir sur blanc’, ‘I read it in black on white’. Does the fact that French has one word only for ‘sand’ and ‘gravel’ – le sable – mean that French speakers have a different mental picture of a beach?
I get fascinated by these small – and probably unscientific – differences, and they have the bonus of clarifying my thinking, of hunting out the imagery behind idioms to check what I actually mean when I use them. Knowing two languages may lead to clearer more nuanced thinking.
The other benefit that researchers often overlook is the access a second language gives you to a crowd of potential friends, to the riches of another culture (not every novel is translated into English, and not every movie is sub-titled), and to seeing history through different eyes (World War 2 has a difference resonance for the French than for us Australians.)
So if you are thinking of learning a new language, commit to a few months, a few years or a lifetime. The very attempt will reap great benefits!
 Paul Nation and Robert Waring, “Vocabulary Size, Test Coverage and Word Lists,” http://www.fltr.ucl.ac.be/fltr/germ/etan/bibs/vocab/cup.html Accessed 22/5/2012
 Jonah Lehrer, “The Benefits of Being Bilingual”, May 15, 2012 Wired Magazine, http://www.wired.com/wiredscience/2012/05/the-benefits-of-being-bilingual/, Accessed 21/5/2012