Have you experienced déjà vu?
你出现过“幻觉记忆”吗？
It's that shadowy feeling you get when a situation seems familiar.
就是那种当下情形似曾相识的模模糊糊的感觉。
A scene in a restaurant plays out exactly as you remember.
餐馆里的一幕，跟你记忆中的一模一样。
The world moves like a ballet you've choreographed,
这个世界的运转就像你编的一场芭蕾舞，
but the sequence can't be based on a past experience because you've never eaten here before.
但这一幕绝对不是出自以前的记忆，因为你从来没在这里用过餐。
This is the first time you've had clams, so what's going on?
这是你第一次点花蛤，所以究竟发生了什么？
Unfortunately, there isn't one single explanation for déjà vu.
可惜，现在对于“幻觉记忆”没有一个确定的解释。
The experience is brief and occurs without notice, making it nearly impossible for scientists to record and study it.
这样的经历很短暂，不能事先预知，所以科学家几乎无法记录和研究这一现象。
Scientists can't simply sit around and wait for it to happen to them -- this could take years.
科学家不能只是坐在那儿等着它发生，这可能需要好几年。
It has no physical manifestations and in studies, it's described by the subject as a sensation or feeling.
幻觉记忆在身体上没有任何表现，研究中，它被实验对象形容为一种神经反应或是感情。
Because of this lack of hard evidence, there's been a surplus of speculation over the years.
正由于缺少有力的根据，这些年来出现了太多种的推测。
Since Emile Boirac introduced déjà vu as a French term meaning 'already seen,'
自从艾米尔·布拉克提出“幻觉记忆”（这个法语词的意思是“以前见过”）以来，
more than 40 theories attempt to explain this phenomenon.
有40多种理论都试图解释这一现象。
Still, recent advancements in neuroimaging and cognitive psychology narrow down the field of prospects.
最近在神经影像学和认知心理学上的进展，缩窄了这个领域的研究前景。
Let's walk through three of today's more prevalent theories, using the same restaurant setting for each.
让我们来瞧瞧目前三种最普遍的说法吧，都用餐厅那个例子作背景。
First up is dual processing. We'll need an action. Let's go with a waiter dropping a tray of dishes.
首先是双过程理论。用一个动作来解释。服务生打翻了一堆碗盘。
As the scene unfolds, your brain's hemispheres process a flurry of information:
随着画面出现，你的大脑开始处理一连串的信息：
the waiter's flailing arms, his cry for help, the smell of pasta.
服务生挥舞双臂，他大声求援，意大利面的香味。
Within milliseconds, this information zips through pathways and is processed into a single moment.
在千分之一秒内，这个信息快速穿梭于神经路径中，最后合为一个瞬间的动作。
Most of the time, everything is recorded in-sync.
大脑通常会同步记录信息。
However, this theory asserts that déjà vu occurs when there's a slight delay in information from one of these pathways.
然而，这个双过程理论声称，当其中一条神经路径的信息被延迟时，“幻觉记忆”就会发生。
The difference in arrival times causes the brain to interpret the late information as a separate event.
信息到达的时间差，导致大脑把迟到的信息理解为另一个事件。
When it plays over the already-recorded moment, it feels as if it's happened before because, in a sense, it has.
当它回放记录好的时刻时，它觉得好像已经发生过了，因为，从某种意义上，这时刻确实发生了。·
Our next theory deals with a confusion of the past rather than a mistake in the present.
我们下一个理论讲的是对于过往的混淆，而不再是对于当下的错误理解。
This is the hologram theory, and we'll use that tablecloth to examine it.
这就是全息理论，我们用这张桌布来检视它。
As you scan its squares, a distant memory swims up from deep within your brain.
当你目光扫过方格时，一个遥远的记忆从你脑海深处浮现。
According to the theory, this is because memories are stored in the form of holograms,
根据这个理论，这是因为记忆是以全息图的形式储存的，
and in holograms, you only need one fragment to see the whole picture.
在全息图里，你只需要一个片段去全览整幅图。

Your brain has identified the tablecloth with one from the past, maybe from your grandmother's house.
你的大脑从之前的记忆中认出了这张桌布，也许是你奶奶家的。
However, instead of remembering that you've seen it at your grandmother's,
然而，你并没清楚记起来这图案是在奶奶家看到的，
your brain has summoned up the old memory without identifying it.
你的大脑召唤出以前的记忆，却没有识别出它。
This leaves you stuck with familiarity, but no recollection.
这让你被似曾相识的感觉困惑住，但就是想不起来。
Although you've never been in this restaurant, you've seen that tablecloth but are just failing to identify it.
虽然你从没来过这家餐厅，但是你见过这张桌布，可你却不能识别出它来。
Now, look at this fork. Are you paying attention?
接下来看看这把叉子。全神贯注了吗？
Our last theory is divided attention,
最后一个理论是分散注意力理论，
and it states that déjà vu occurs when our brain subliminally takes in an environment while we're distracted by one particular object.
该理论声称，“幻觉记忆”发生在当我们大脑潜意识地接收一个场景，而我们却被特定的一件事分散了注意力的时候。
When our attention returns, we feel as if we've been here before.
当我们的注意力回来的时候，我们就觉得我们以前来过这儿。
For example, just now you focused on the fork and didn't observe the tablecloth or the falling waiter.
比如，你刚刚专注地盯着这个叉子，但是没注意到这张桌布还有摔倒的服务生。
Although your brain has been recording everything in your peripheral vision, it's been doing so below conscious awareness.
虽然你的大脑记录了你周边的一切，但那都是在不被察觉的状况下进行的。
When you finally pull yourself away from the fork,
当你的注意力从叉子上抽离，
you think you've been here before because you have, you just weren't paying attention.
你就觉得，你来过这儿，因为你确实已经来过，你只是没注意。
While all three of these theories share the common features of déjà vu,
这三种理论都有“幻觉记忆”的特征，
none of them propose to be the conclusive source of the phenomenon.
但哪种都不能被定为这一现象的结论性的缘由。
Still, while we wait for researchers and inventers to come up with new ways to capture this fleeting moment,
虽是如此，尽管我们期待研究人员和发明家提出更好的新方法来捕捉这稍纵即逝的瞬间，
we can study the moment ourselves.
我们还可以自己研究这一时刻。
After all, most studies of déjà vu are based on first-hand accounts, so why can't one be yours?
毕竟大多数对于幻觉记忆的研究都来自第一手资料，为什么不能是你的？
The next time you get déjà vu, take a moment to think about it.
下次当你再出现记忆幻觉时，花点时间想一想。
Have you been distracted? Is there a familiar object somewhere?
你的注意力分散了吗？周围有没有熟悉的物品？
Is your brain just acting slow? Or is it something else?
还是说你的大脑运转慢了？还是另有其因？