什么是既视感（Déjà vu）？：英语精读讲义

Hey Vsauce, Michael here and today we're going to discuss déjà vu.

嘿，Vsauce，我是 Michael，今天我们来聊聊既视感。

What is it and why does it occur?

它是什么，又为什么会出现？

You know, those moments where the current situation feels like it's happened before. 短語搭配

你知道，就是那种感觉眼前的情景以前发生过的时刻。

You're certain it has, but you don't know when or how it became so familiar.

你确信它发生过，却不知道是在何时，也不知道它为何会如此熟悉。

It's difficult to scientifically study déjà vu because there's no reliable way to cause it to happen in people's heads in a laboratory.

要用科学方法研究既视感很困难，因为在实验室里，没有可靠的方法能让这种感觉出现在人的脑海中。

But here's what we do know. 表達脈絡

不过，下面这些是我们确实知道的。

Humans don't seem to experience déjà vu until they're at least 8 or 9 years old.

人类似乎至少要到 8、9 岁才会体验到既视感。

It's most frequent in your teens and 20s and then tapers off as you get older. 短語動詞

它在十几岁和二十多岁时最常见，之后会随着年龄增长逐渐减少。

So it might have something to do with brain development. 短語搭配

所以，它或许与大脑发育有关。

In fact, we should probably go get ourselves a brain.

其实，我们也许该去弄个大脑来。

That was easy.

真轻松。

Now, like a stomach ache, déjà vu may be a symptom with many possible causes.

既视感就像胃痛一样，可能是一种症状，背后有许多可能的成因。

A lot of the popular theories about what causes it involve

关于既视感为何出现，许多流行理论都认为，问题出在

a disconnect that may be occurring between the deep structures of the brain that process our experiences unconsciously

无意识处理我们经历的大脑深层结构

and the parts of the brain that are conscious of what we experience, process it, and then tell us what we're seeing.

与有意识地感知和处理经历、再告诉我们看到了什么的大脑区域之间可能出现了脱节。

For the sake of simplicity, let's begin with the visual system. 短語搭配

为了简单起见，我们先从视觉系统说起。

Now, the brain sits in your head like this and your eyeballs are over here seeing things,

大脑像这样待在你的脑袋里，而眼球在这边观察事物，

sending that signal to the back of the brain, the occipital lobe, where visual cortex is.

再把信号传到大脑后部的枕叶，也就是视觉皮层所在的位置。

That's where the image is processed and we become aware of what we're seeing.

图像就是在那里得到处理，我们也由此意识到自己看到了什么。

But visual cortex isn't the first stop that information makes. 習語

但视觉皮层并不是这些信息到达的第一站。

Instead, we know that it stops in lots of other places.

我们知道，信息其实还会经过许多其他地方。

For instance, the amygdala, where it may be processed at an involuntary emotional level.

比如杏仁核，信息可能会在那里从不由自主的情绪层面得到处理。

And this fun little part right here, number 31, the tectum.

还有这里这个有趣的小部位，31 号，也就是顶盖。

It's involved in preliminary visual processing and helps control eye movements.

它参与初步的视觉处理，还有助于控制眼球运动。

Now that fact is incredibly important

这一点极其重要，

because what it means is that people with blindness caused by brain damage to the visual cortex cannot see anything. 語法

因为这意味着，因视觉皮层受损而失明的人什么都看不见。

They don't report seeing or recognizing anything.

他们不会表示自己看见或认出了任何东西。

However, the other preliminary parts of the brain that get that message are still healthy.

然而，大脑中其他接收该信号、负责初步处理的部位仍然健康。

And so, despite being legally blind, these people exhibit what is known as blindsight. 文化背景

因此，这些人尽管在法律意义上属于盲人，却会表现出所谓的“盲视”。

They can defy all odds and avoid an obstacle course on the ground. 習語

他们甚至能出人意料地避开地面上设置的一连串障碍。

They can also be presented faces showing joy or anxiety and fear

还可以给他们看表现出喜悦、焦虑或恐惧的面孔，

and feel without knowing why at all on Earth they feel that way a similar emotion.

而他们会产生类似的情绪，却完全不知道自己究竟为何会有这种感觉。

So a lot is going on when we look at things. 短語動詞

所以，我们看东西时，大脑其实在进行很多活动。

And if those preliminary structures in the vision system allow certain blind people to be oddly and unconsciously aware of what they're looking at,

如果视觉系统中的这些初步处理结构，能让某些盲人以一种奇特而无意识的方式察觉自己所看的东西，

we may have the ingredients we need for this disconnect.

那么，我们也许就有了产生这种脱节所需的要素。

Think of it this way. 表達脈絡

可以这样理解。

If I experience event A and then B and then C

假设我依次经历了事件 A、B 和 C，

and the inner parts of my brain commit it to memory and generate an emotional response, 短語搭配

大脑内部区域把它们存进记忆，并产生情绪反应，

but then a fraction of a second later out of sync, 講解

但晚了几分之一秒，时间上没能同步，

my visual cortex finally gets around to telling me, the conscious aware part of my brain, what I'm seeing, 短語動詞

我的视觉皮层才终于把我看到的东西告诉“我”，也就是大脑中有意识、有觉知的部分，

it'll say, "Okay guys,

它会说：“好了，各位，

we're looking at A and then B and then"

我们看到的是 A，然后是 B，接着是——”

and the brain says, "Woah, woah, woah.

大脑却说：“哇，哇，哇。

Wait, wait.

等等，等等。

And then C, right?

接下来是 C，对吧？

I mean, it's already happened,

我是说，这明明已经发生过了，

I thought. Wait, wait."

我刚才就这么觉得。等等，等等。”

And that may be déjà vu.

这或许就是既视感。

But what could cause these processes dealing with the same information to get temporarily out of sync like that?

但处理同一信息的这些过程，为什么会像这样暂时失去同步呢？

Well, it's probably a neurological abnormality,

嗯，很可能是某种神经系统异常，

possibly an epileptic episode where neurons all fire in sync. 用詞

也可能是一次所有神经元同步放电的癫痫发作。

We also know that patients who experience chronic and persistent déjà vu tend to have brain damage in the temporal lobes of their brain. 語法

我们还知道，长期持续出现既视感的患者，其大脑颞叶往往有损伤。

These lobes on either side.

就是两侧的这两个脑叶。

Well, that sounds kind of bad, right? 語氣意圖

听起来有点糟糕，对吧？

I mean, when I experience déjà vu, should I run to the doctor right away? 短語搭配

那我一有既视感，是不是就该立刻跑去看医生？

Well, not at all. 語氣意圖

完全不用。

In fact, minor epileptic events are quite common.

其实，轻微的癫痫性活动相当常见。

You've probably experienced a similar phenomenon known as a hypnagogic jerk. 文化背景

你很可能体验过一种类似的现象，叫作入睡抽动。

That's a fancy name for what occurs when you're about to fall asleep 講解

这是一个听起来很专业的名称，指的是你快要睡着时，

and then all of a sudden you feel like you're falling or that you tripped and your body jolts itself awake. 短語搭配

突然觉得自己在下坠或绊了一跤，身体猛地一抽，把自己惊醒。

What's going on there is that as you fall asleep, 語法

这里发生的情况是，当你逐渐入睡时，

your muscles relax and some part of your brain that's still awake notices that and feels like you're no longer supported. 語法

肌肉会放松，而大脑中某个仍醒着的部分注意到了这一点，并觉得你的身体失去了支撑。

You must be falling and it sends out a huge signal that causes all of your muscles to twitch, waking you up. 講解

它认定你一定是在下坠，于是发出强烈信号，让全身肌肉抽动，把你唤醒。

Oh, and déjà vu is not the only vu out there.

哦，对了，有“vu”的可不只有 déjà vu（既视感）。

There's also something known as presque vu or tip of the tongue. 習語

还有一种叫 presque vu，也就是“话到嘴边”现象。

And this is what happens when you're familiar with something, 短語搭配

当你对某样东西很熟悉时，就可能出现这种现象：

you know you know it, but for the life of you at that moment you cannot recall it. 習語

你知道自己明明知道，但那一刻无论如何就是想不起来。

It's like "What's that actor's name from that movie?

就像：“那部电影里的那个演员叫什么来着？

I've seen it 18 times.

我都看过 18 遍了。

How can I not remember it? 語氣意圖

我怎么会想不起来？

Wow."

天啊。”

One explanation of how that happens is that other words similar to the target word are being remembered

对这种现象的一种解释是，大脑正在回想与目标词相似的其他词语，

and to help you out, your brain is actively blocking other stuff around it, including the word you're actually looking for. 短語動詞

为了帮你找到答案，大脑会主动屏蔽周围的其他内容，其中也包括你真正要找的那个词。

Now, this explanation is really nice because it might help explain why presque vu has a shared or social aspect.

这个解释很不错，因为它或许能说明为何 presque vu 会呈现出群体性或社交性。

Even a bunch of people in a group, all with separate brains,

即使一群人的大脑彼此独立，

if they're given the same blocking words that are related,

如果给他们同样一组会造成阻碍的相关词语，

no one in the group can come up with the name until the subject is changed 短語動詞

那么在话题改变之前，组里谁也说不出那个名字；

and those words are no longer blocked and then all of a sudden someone goes,

等那些词不再受到屏蔽，突然就会有人说：

"Oh, Gary Sinise, that's who it was. 語法

“哦，是 Gary Sinise，原来是他。

Yeah, there you go." 語氣意圖

对，就是他。”

Okay, finally, jamais vu.

好，最后来说 jamais vu，也就是“陌生感”。

This is when something that you know,

这是指你知道的某样东西，

something that you're familiar with, all of a sudden seems brand new and bizarre. 短語搭配

某个你很熟悉的东西，突然显得全新而又怪异。

Schizophrenic patients will sometimes see people they know and insist that it's not the person they know. 短語搭配

精神分裂症患者有时会看到自己认识的人，却坚称对方不是自己认识的那个人。

Instead, it's an imposter.

而是一个冒牌货。

But all of us have probably experienced jamais vu to a certain extent. 短語搭配

不过，我们每个人或多或少可能都体验过 jamais vu。

For instance, when you repeat a word over and over and over and over and over and over again, 短語搭配

比如，当你把一个词一遍又一遍又一遍又一遍又一遍又一遍地重复时，

the word starts to lose its meaning and you start to think, 短語搭配

这个词会开始失去意义，而你会开始想：

"What? How is this even a word? 語氣意圖

“什么？这怎么会是一个词？

It's so weird."

太奇怪了。”

Well, scientists believe that happens because continuing to excite the neurons responsible for that word

科学家认为，这是因为持续刺激负责该词的神经元，

causes them to become inhibited and further use is less intense.

会使它们受到抑制，之后再使用时，反应强度就会减弱。

It's just crazy to think that there's so much out there in the world, in the universe, 語氣意圖

想想就觉得不可思议：在这个世界、这个宇宙中，还有那么多事物

that we don't know, that we don't understand, that we haven't yet discovered. 表達脈絡

是我们不知道、不理解、尚未发现的。

But yet that very feeling of familiarity for what we do know can't always be trusted. 語法

可即便如此，我们对已知事物产生的那种熟悉感，也并非总是可信。

About the only constant seems to be, 語法

似乎唯一不变的只有一件事——

as always, thanks for watching.

还是那句话，感谢观看。