He isolated which muscles are behind our expressions of terror, sadness and joy.

他分析出了控制我們表達恐懼、悲傷和快樂的肌肉。

While many muscles in our face can simulate a smile, only two produce a genuine smile--one under our eyes and another on the side of our cheeks.

許多臉部肌肉可以模仿出笑容，但只有兩條肌肉能產生真誠的笑容，一條在我們的眼睛下，另一條在我們臉頰兩側。

It looks like your eyes are smiling, too.

這讓我們的眼睛看起來也在微笑。

Psychologists call this a Duchenne smile.

心理學家稱之為「杜鄉的微笑」。

Joy and happiness make us genuinely smile, but can smiling make us genuinely happy?

我們因快樂與喜悅散發真誠的微笑，但笑容能讓我們感到真正的快樂嗎？

Inspired by Duchenne’s work, Charles Darwin suggested that our facial movements influence our emotional experiences.

受到 Duchenne 的啟發，Charles Darwin 認為臉部肌肉的動作影響了我們的情緒。

There’s a feedback loop, so looking scared would make you more fearful and a genuine smile would make you happy.

因為反饋迴路的關係，因此當你看起來很害怕會讓你變得更害怕；而一個真誠的笑容會讓你感到快樂。

It’s called the “Facial Feedback Hypothesis”.

這叫做「臉部回饋假說」。

Skip forward a century, an American psychologist Paul Ekman monitored the smiles of a group of women while they watched a series of movies.

一個世紀後，一位美國心理學家 Paul Ekman 讓一群女性看一系列的電影以研究他們的笑容。

Those who smiled genuinely (a Duchenne smile) and moved those muscles near their eyes reported feeling significantly more amused and happier than those who didn’t smile.

研究指出，露出真誠笑容（杜鄉的微笑）並使用眼部肌肉的女性與沒有嶄露笑容的人相比，感到更快樂。

So he came to the astonishing conclusion that we smile when we're happy.

因此他下了驚人的結論：當我們感到快樂時會露出笑容。

In a more recent study, one group of participants received botox treatment for frown lines, which paralyzed the corrugator muscles in their brow.

一個近期的研究中，一群參與者們接受肉毒桿菌施打在眉間皺紋的治療，讓眉毛下的皺眉肌無力運動。

The participants couldn’t express sad or distressed emotions in their face, and their reported positive mood was higher than other participants who received different cosmetic procedures.

參與者們無法表達難過或哀傷的神情，且研究發現相較於接受其他整形手術的人們，參與者的情緒顯得相當正面積極。

Aside from genuine smiles and frown-muscle paralysis, there’s hope for our fake smiles too.

除了真誠的微笑與無力的皺眉肌肉，假笑也是有好處的。

One study found that when participants were asked to fake a smile while completing a stressful activity,

一項研究指出，當參與者們被要求露出假笑完成一項壓力很大的活動時，

they had lower heart rates during a stressful recovery period than those with the neutral expression.

相較於那些被要求保持一般表情的人們，他們在壓力回復時期時的心跳速度會變慢。

So forcing yourself to smile can make you happier.

因此讓自己保持笑容的確能變得快樂。

It goes to show that if you grin and bear it, it’s more likely your sadness and stress will help to hibernate your worries away.

當你奮力把笑容掛在臉上，你的悲傷和壓力就更有可能幫你緩解煩惱。

And if you don't already, subscribe to BrainCraft for a new brainy video every Thursday.

還沒訂閱的快訂閱 BrainCraft ！每周四會有更多知識影片喔！