If you answered, "sí," "oui," or "會" and you're watching this in English, chances are you belong to the world's bilingual and multilingual majority.

如果你回答「是」(西班牙文)「是的」(法文) 或者「會」，而你又正在觀看英文版的影片，那你很有可能屬於，這世上會雙語或者多語的多數人。

And besides having an easier time traveling or watching movies without subtitles, knowing two or more languages means that your brain may actually look and work differently than those of your monolingual friends.

除了在旅行時碰到較少麻煩或者看電影時不需要字幕，若你會兩種或以上的語言可能代表你的大腦也許實際上看起來、運作起來都有別於那些只會一種語言的朋友。

So what does it really mean to know a language?

所以到底什麼才叫做「會一種語言」？

Language ability is typically measured in two active parts, speaking and writing, and two passive parts, listening and reading.

語言能力的評估通常分成兩項主動能力：說和寫，以及兩項被動能力：聽和讀。

While the balanced bilingual has near equal abilities across the board in two languages, most bilinguals around the world know and use their languages in varying proportions.

一個協調的雙語者擁有相當程度的兩種語言能力，然而世界上大多的雙語者對於自己語言的瞭解以及使用皆不盡相同。

And depending on their situation and how they acquired each language, they can be classified into three general types.

而且依照不同的狀況以及他們學習每種語言的方式，我們可將這些雙語者大致上分成三類。

For example, let's take Gabriella, whose family immigrates to the US from Peru when she's two years old.

我們以 Gabriella 為例，她的家人在她兩歲的時候從秘魯移民至美國。

As a compound bilingual, Gabriella develops two linguistic codes simultaneously.

身為一位「複合型雙語者」，Gabriella 同時發展了兩種語言代碼。

With a single set of concepts, learning both English and Spanish as she begins to process the world around her.

她對週遭的世界開始進行認知過程，是以一組概念學習英文和西班牙文兩種語言。

Her teenage brother, on the other hand, might be a coordinate bilingual.

另一方面，她的青少年哥哥可能是個「並列型雙語者」。

Working with two sets of concepts: learning English in school, while continuing to speak Spanish at home and with friends.

他的大腦裡有兩組概念在運作：在學校學習英文，同時在家或者跟朋友在一起時繼續說西班牙文。

Finally, Gabriella's parents are likely to be subordinate bilinguals, who learn a secondary language by filtering it through their primary language.

最後，Gabriella 的父母很有可能成為「從屬型雙語者」：他們在學第二語言時，會以自己的第一語言來過濾第二語言。

Because all types of bilingual people can become fully proficient in a language regardless of accent or pronunciation, the difference may not be apparent to a casual observer.

以上所有類型的雙語者不談口音或者發音，都可以完全精通他們的第二語言；若不仔細觀察，這些差異並不明顯。

But recent advances in brain imaging technology have given neurolinguistics a glimpse into how specific aspects of language learning affect the bilingual brain.

然而近來，最新大腦成像技術讓神經語言學者有機會窺探特定的語言學習區塊，是如何影響雙語者的腦袋。

It's well known that the brain's left hemisphere is more dominant and analytical in logical processes, while the right hemisphere is more active in emotional and social ones.

大家都知道，左腦半球支配性較強而且能進行邏輯過程的分析，而右腦在情感和社交方面比較活躍。

Though this is a matter of degree, not an absolute split.

雖然這種看法，在某種程度上獲得認可，但也不是百分百正確。

The fact that language involves both types of functions while lateralization develops gradually with age has led to the critical period hypothesis.

語言包括兩種類型的功能，偏側性隨著年齡逐年發展的事實，引出了所謂「關鍵時期」的假設。

According to this theory, children learn languages more easily because the plasticity of their developing brains lets them use both hemispheres in language acquisition, while in most adults, language is lateralized to one hemisphere, usually the left.

根據這個理論，孩子們較容易學習語言，因為他們發育中的大腦有可塑性這讓他們可以使用大腦的兩個半球來學習語言；而大多數的成人只使用一個半腦來學習語言，通常是左半腦。

If this is true, learning a language in childhood may give you a more holistic grasp of its social and emotional contexts.

如果這是真的，若你在孩童時期學習語言，那麼在語言使用上的社交和情感的情境，你應該會有更完整的理解。

Conversely, recent research showed that people who learned a second language in adulthood exhibit less emotional bias and a more rational approach when confronting problems in the second language than in their native one.

相反地，最近的研究顯示在成人時期學習第二語言的人顯示出較少情緒上的偏見，且比起在學習自己的母語時，運用較理性的方式來面對學習第二外語時碰到的困難。

But regardless of when you acquire additional languages, being multilingual gives your brain some remarkable advantages.

儘管如此，當你在學習其他語言時，多重語言者的身分將為你的大腦帶來一些了不起的優勢。

Some of these are even visible, such as higher density of the grey matter that contains most of your brain's neurons and synapses, and more activity in certain regions when engaging a second language.

而有些是非常顯見的，例如灰質的密度會比較高，灰質中含有大腦大部分的神經元以及突觸；其他優勢還包括了，當你在使用第二語言時，某些腦區域會更加活躍。

The heightened workout a bilingual brain receives throughout its life can also help delay the onset of diseases, like Alzheimer's and dementia by as much as five years.

若雙語者的大腦持續地接收這些增強的練習，會幫助延緩一些疾病如阿茲海默症和失智的發作，最多可延緩五年。

The idea of major cognitive benefits to bilingualism may seem intuitive now, but it would have surprised earlier experts.

習用雙語能享受到許多的好處這樣的想法在現今也許被視為理所當然，然而早期的專家會對此概念感到驚訝。

Before the 1960s, bilingualism was considered a handicap that slowed a child's development by forcing them to spend too much energy distinguishing between languages, a view based largely on flawed studies.

在1960年代前，雙語的能力被視為一種障礙，因為它會減緩孩子的發展：他們被迫花費太多精力在辨認兩種語言的異同，然而這種觀點大多基於有瑕疵的研究。

And while a more recent study did show that reaction times and errors increase for some bilingual students in cross-language tests.

而雖然近代研究顯示一些會雙語的學生，當他們在做跨語言測驗時，反應時間和失誤都增加了；

It also showed that the effort and attention needed to switch between languages triggered more activity in, and potentially strengthened the dorsolateral prefrontal cortex.

此研究也顯示，轉換兩種語言需要的努力以及專注力以引起更多活動產生，這很有可能強化背外側前額葉。

This is the part of the brain that plays a large role in executive function, problem solving, switching between tasks, and focusing while filtering out irrelevant information.

背外側前額葉在大腦中主要負責決策功能、問題解決、任務轉換，以及在過濾不相關訊息時保持專注力。

So, while bilingualism may not necessarily make you smarter, it does make your brain more healthy, complex and actively engaged.

所以即使雙語這項能力無法讓你變聰明，它還是能讓你的頭腦變得更健康、更複雜、更活躍。

And even if you didn't have the good fortune of learning a second language as a child, it's never too late to do yourself a favor and make the linguistic leap from, "Hello," to, "Hola," "Bonjour" or "您好"。

即便你小時候沒有機會學第二種語言，踏出自己的那一步開始說「哈囉」(西班牙文)「你好」(法文) 或「您好」，永遠不嫌晚。

Because when it comes to our brains, a little exercise can go a long way.

因為動的是我們的腦袋，一點小活動就能對腦袋大有幫助。