Guidebooks explain to tourists that Americans smile to strangers a lot.

旅遊指南都會跟觀光客指出，美國人很常對陌生人微笑。

So, why do Americans smile so much, and why is that so strange to everyone else?

為什麼美國人那麼常微笑呢？又為什麼這對外國人而言很奇怪？

Americans seem to smile even when there's not a very good reason to.

美國人似乎就算沒有理由要微笑。

When you see an American smiling, they might be feeling happy, confident, or neutral.

當你看到一個美國人微笑時，他可能感到開心、有自信，或是沒什麼特別的感覺。

Sometimes, just a polite way to make someone else feel comfortable.

有時候，這只是基於禮貌，好讓對方感到舒服。

Think "service with a smile."

試著聯想「面帶微笑的服務」

Here's your receipt. Thank you very much!

這是您的發票，非常感謝！

In other countries, though, smiling for no reason can make you seem kind of dumb.

然而，在其他國家，如果你沒有理由微笑卻這麼做，會讓你看起來有點蠢。

One researcher found in countries like Japan, India, South Korea, and Russia, smiling faces were considered less intelligent than serious ones.

有研究者發現，在日本、印度、南韓和俄羅斯，面帶微笑的臉龐被認為比嚴肅的臉孔要顯得比較不聰明。

His theory is that there's a connection between a country's level of instability and finding smiling stupid.

他的論點是，一國的局勢越不穩定，越傾向認為微笑是愚蠢的。

After all, how can you be so confident and happy when the future's uncertain?

是啊，如果對未來感到迷惘，怎麼會有信心或愉快呢？

That might help explain stereotypically frowning places like Russia, where smiling in photos isn't really a thing.

這能解釋為什麼在有些被認為是愁眉苦臉的國家，像是俄羅斯，人們很少拍照時微笑。

There's also some interesting research that helps explain the other end of the spectrum: why Americans have stereotypically mega-watt smiles.

也有一些有趣的研究得以解釋另一個極端：為什麼美國人如此笑容可掬。

It turns out that countries with a long, robust history of immigration have historically relied more on nonverbal communication.

那是因為移民國家在過去歷史發展比較仰賴肢體語言來溝通。

Therefore, people there might smile more.

因此，人們會比較常微笑。

In a recent study, researchers looked at the number of "source countries" that have fed into a country since Columbus arrived in the Americas.

有個近期研究的研究者觀察自哥倫布來到美洲以來各國人口組成的「移入國」數目。

Places like Canada and the United States are very diverse, with more than 60 source countries. But places like China and Zimbabwe are more homogenous, with just a few nationalities represented in their populations.

有些國家，例如加拿大和美國是非常多元的，有超過 60 個「移入國」。但中國和辛巴威等國家的族群組成則較單一，人口組成只有少數幾個族裔。

The authors found that emotional expressiveness was correlated with diversity.

筆者發現，情緒的表達能力和多元程度呈現正相關。

In other words, when there are a lot of immigrants around, you might have to smile more to build trust and cooperation, since you don't all all speak the same language.

也就是說，如果周圍有很多移民，你可能就更需要透過微笑來建立信任感和合作的意願，因為你們說的語言都不同。

But in the countries that are less-diverse, people were more likely to smile to show they were superior to one another.

但在族群組成較不多元的地方，人們微笑的原因，比較是用來展現優越感。

In these countries, smiling is a way to preserve the hierarchy.

在這些國家，微笑是用來鞏固既有社會階層關係。

But American's just don't smile more often, they also smile much more enthusiastically.

但美國人不只是比較常微笑而已，他們的笑容也開朗許多。

For a study published last year, researchers compared the official photos of American and Chinese business and government leaders.

在去年一份研究報告中，研究者比較了美國和中國政商界領導人的官方個人照。

After coding them according to their levels of "facial muscle movement", they found that American leaders in all contexts were both more likely to smile and showed more excited smiles than the Chinese leaders did.

根據他們「臉部肌肉活動」程度進行量化分類後，他們發現在所有情況下，美國領導人比中國領導人更傾向微笑，也笑得更興奮。

Later, they found the more a country's college students valued happy, high-energy emotions, the more excited the government officials from those countries looked in their photos.

而後，他們也發現，一國的大學生越是偏好快樂、興奮的感覺，該國的政府官員在照片中也會顯得更興奮。

Cultural differences in smiling don't just confuse foreign tourists visiting the United States.

微笑所造成的文化差異不只是使來美國的觀光客感到困惑。

They also come as a surprise for American companies doing business abroad.

美國人在海外做生意也會感到驚訝。

When McDonalds went to Russia in the 90s, they had to coach their employees on how to smile.

麥當勞在 1990 年代拓展到俄國時必須教導當地員工如何微笑。

But when WallMart opened stores in Germany, it had to tell its sales clerks to stop smiling at customers because some people saw it as flirting.

但沃爾瑪到德國時卻叫收銀員不要對顧客微笑因為有些顧客認為這是在調情。

In other words, the American smile is a product of its culture.

換句話說，美式的微笑是文化產物。

And like any other product, we try to export it around the world.

如同其他產品，我們也試著將它出口到世界各國。

This is "You Are Here", a new series about the science behind everyday life.

您正在收看 You Are Here，一個關於日常生活背後的科學原理的新系列。

Let us know what topics you want us to explore in the comments.

歡迎在留言區讓我們知道你想了解哪些主題。

I'm Olga Khazan, thank you for watching.

我是 Olga Khazan，謝謝觀賞。