Oh, excuse me! Have you ever yawned because somebody else yawned? You aren't especially tired, yet suddenly your mouth opens wide and a big yawn comes out. This phenomenon is known as contagious yawning. And while scientists still don't fully understand why it happens, there are many hypotheses currently being researched. Let's take a look at a few of the most prevalent ones, beginning with two physiological hypotheses before moving to a psychological one. Our first physiological hypothesis states that contagious yawning is triggered by a specific stimulus, an initial yawn. This is called fixed action pattern. Think of fixed action pattern like a reflex. Your yawn makes me yawn. Similar to a domino effect, one person's yawn triggers a yawn in a person nearby that has observed the act. Once this reflex is triggered, it must run its course. Have you ever tried to stop a yawn once it has begun? Basically impossible! Another physiological hypothesis is known as non-conscious mimicry, or the chameleon effect. This occurs when you imitate someone's behavior without knowing it, a subtle and unintentional copycat maneuver. People tend to mimic each other's postures. If you are seated across from someone that has their legs crossed, you might cross your own legs. This hypothesis suggests that we yawn when we see someone else yawn because we are unconsciously copying his or her behavior. Scientists believe that this chameleon effect is possible because of a special set of neurons known as mirror neurons. Mirror neurons are a type of brain cell that responds equally when we perform an action as when we see someone else perform the same action. These neurons are important for learning and self-awareness. For example, watching someone do something physical, like knitting or putting on lipstick, can help you do those same actions more accurately. Neuroimaging studies using fMRI, functional magnetic resonance imaging, show us that when we seem someone yawn or even hear their yawn, a specific area of the brain housing these mirror neurons tends to light up, which, in turn, causes us to respond with the same action: a yawn! Our psychological hypothesis also involves the work of these mirror neurons. We will call it the empathy yawn. Empathy is the ability to understand what someone else is feeling and partake in their emotion, a crucial ability for social animals like us. Recently, neuroscientists have found that a subset of mirror neurons allows us to empathize with others' feelings at a deeper level. (Yawn) Scientists discovered this empathetic response to yawning while testing the first hypothesis we mentioned, fixed action pattern. This study was set up to show that dogs would enact a yawn reflex at the mere sound of a human yawn. While their study showed this to be true, they found something else interesting. Dogs yawned more frequently at familiar yawns, such as from their owners, than at unfamiliar yawns from strangers. Following this research, other studies on humans and primates have also shown that contagious yawning occurs more frequently among friends than strangers. In fact, contagious yawning starts occurring when we are about four or five years old, at the point when children develop the ability to identify others' emotions properly. Still, while newer scientific studies aim to prove that contagious yawning is based on this capacity for empathy, more research is needed to shed light on what exactly is going on. It's possible that the answer lies in another hypothesis altogether. The next time you get caught in a yawn, take a second to think about what just happened. Were you thinking about a yawn? Did someone near you yawn? Was that person a stranger or someone close? And are you yawning right now? (Yawn) (Lip smacking)
不好意思! 別人打哈欠 你會不會也打哈欠? 其實沒有特別累 但突然就張大嘴巴 一個大哈欠 就跑出來了 這現象叫哈欠傳染 對於背後的原因 科學家還不完全了解 但已經有人在研究各種假說 讓我們來了解 一些廣為流傳的說法 先聽聽 2 種生理假說 再看看 1 種心理假說 第 1 種生理假說認為 哈欠傳染其來有自 會由特定刺激引起 就是最初的哈欠 這叫固定行為模式 有點像反射動作 你的哈欠讓我打哈欠 類似多米諾骨牌效應 一個人的哈欠 讓附近看到的人也打哈欠 這效應一旦啟動 就會持續一定的時間 快打哈欠時 你有試過阻止自己嗎? 根本不可能! 第 2 種生理假說 叫無意識模仿 又稱變色龍效應 人會模仿他人的行為 下意識地 做出細微、自然的複製動作 人會模仿他人的姿勢 像是對面的人翹腳 你看到了 很有可能也會翹起腳來 這假說認為 看到別人打哈欠就跟進 是因為不知不覺中 我們會模仿他人的行為 科學家相信 變色龍效應可能和特殊的神經元有關 也就是鏡像神經元 鏡像神經元是一群腦細胞 像鏡子一樣 看到他人的動作後 我們會做出相同的動作 這組神經元很重要 尤其對學習和自我覺察 例如,看到別人的動作 像是編織 或是擦口紅 能讓我們精確地做出相同的動作 腦神經影像利用醫學技術 也就是功能性核磁共振造影 發現看到別人打哈欠 或只是聽到哈欠聲 我們腦中 有鏡像神經元的區塊 會有反應 促使我們做出回應 重複相同的動作:打哈欠 最後要談的心理假說 也和鏡像神經元有關 稱為同理哈欠 同理心是種能力 能感知他人的感受 融入對方的情緒 對人這種社會性動物很重要 近來,神經學家發現 鏡像神經元有組子集 能讓我們同理他人 而且是深層同理 事實上 同理哈欠現象 是在測試固定行為時 所發現的 這研究假設 如果狗聽到人類打哈欠 也會反射性地打起哈欠 不僅證實了這種現象 還發現了其他有趣的事 熟人的哈欠對狗比較有影響力 像是主人 但對陌生人就不是了 同樣地 以人類和靈長類為研究對象 也證實哈欠傳染 在熟人間發生的機率高於陌生人 事實上,早在4、5 歲時 對哈欠傳染就有反應了 那時 兒童開始能正確了解他人的情緒 儘管相關研究推陳出新 想證明哈欠傳染的產生 是因為同理能力 但其實 更需要研究的是背後的機制 說不定真正的答案 就藏在其他假說裡 下次打哈欠時 停下來想想剛才的情形 是不是想到了哈欠這件事? 附近有人打哈欠嗎? 是熟人?還是陌生人? 你現在在打哈欠嗎?