Sherlock Holmes, the legendary detective, had a theory that the brain is like an attic where a person can only store a limited amount of memories.

傳奇偵探夏洛克．福爾摩斯，他有個理論是大腦像閣樓一樣，一個人只能儲存有限的記憶量。

Dr. Watson once told him that the Earth travels around the sun, duh, to which Holmes replied,

華森醫生曾經告訴他，地球繞著太陽運行，呃，對此福爾摩斯回應，

“Now that I do know it I shall do my best to forget it.”

「既然我知道了，我應該盡我所能忘記它。」

Holmes figured, clutter your attic with random facts and trivia, and you won't have room

福爾摩斯認為，用任意事實與瑣事塞滿你的閣樓，你就沒有足夠的空間

for the things that matter, like identifying the tiny differences between lethal poisons.

來處理重要的事，像是辨識致死毒藥間的微小差異。

Was Holmes right?

福爾摩斯說的是對的嗎？

Is our memory limited, like the storage capacity of a computer?

我們的記憶是有限的嗎？就像電腦的儲存空間？

Or is our memory unlimited?

還是說我們的記憶是無限的？

And if we did have perfect memory, what would life be like if you never forgot anything?

如果我們有完美的記憶，從不忘記任何事的人生會是如何呢？

The animated film Inside Out depicted memories as glowing spheres stacked in the brain, like

動畫片《腦筋急轉彎》將記憶描繪成堆積在大腦內的光球，

books in a library.

就像是圖書館裡的藏書。

But the reality is a little more complicated.

但實際上稍微更複雜些。

There is no one place in the brain that serves as our memory bank.

大腦裡並沒有專職負責記憶的記憶銀行。

Instead, individual memories are scattered all over the brain.

相反地，個別記憶會散布在大腦各處。

Many brain cells, in several different regions, work together to make one memory.

分布在數個不同區塊的許多腦細胞，會一同合作創造出一個記憶。

For example, a memory of eating grandma's apple pie might involve some brain cells to

舉例來說，一個吃著祖母的蘋果派的記憶可能包含一些幫助你記得派看起來長甚麼樣子的腦細胞、

help you remember what the pie looked like, others to remember the smell of the cinnamon,

還有一些幫你記得肉桂的味道、

and even cells to remember the delicious taste – just to name a few.

還有幫你記得美味口感的腦細胞——僅舉幾個為例。

In reality, though, a memory isn't a physical thing that we can find in any given brain cell.

可是，實際上記憶不是一個我們能在任何腦細胞裡找到的物理性質的東西。

It's an action, not an object.

它是一種作用，而不是一種物體。

Think of baseball fans doing “the wave”: no single fan IS the wave, the magic only

想想籃球粉絲在做「波浪舞」：不是單一的粉絲可以形成波浪，

happens when all the fans are together, doing their thing in a specific order.

這神奇的景象只發生在所有粉絲一同依特定順序做出行動。

In the same way, a memory only happens when many connected neurons fire in a specific pattern.

同樣地，一個記憶的形成只發生在當許多連結的神經元依特性形態激發時。

And because the same cells can fire in many unique patterns, one group of neurons can encode multiple memories.

然後，因為同樣的細胞可以許多獨特的形態激發，一團神經元可以編碼多樣的記憶。

This increases the memory storage capacity of the brain.

這使大腦的記憶儲存能力提升。

Buried deep in the middle of the brain we find a group of cells shaped like a seahorse,

我們在大腦中央發現一團外形像海馬的腦細胞，

which is why 18th century scientists named this bit the 'hippocampus.'

這也是十八世紀科學家將它命名為「海馬迴」的原因。

Without your seahorse, you might never remember.

你沒有海馬迴的話，你可能就記不得任何事。

We owe a lot of our understanding of memories to one famous patient, known for years only by his initials, H.M.

我們對於記憶的了解很大部份要歸功於一位著名的病人，在數年來我們只知道它的名字首字母是 H.M.。

In 1953, H.M. underwent a surgery for epilepsy which demolished most of his hippocampus,

西元 1953 年，H.M. 經歷了一次癲癇手術，這次手術移除了大部分的海馬迴，

and for the rest of his life, he exhibited a severe type of amnesia where he was unable

在他的餘生中，他出現嚴重的失憶症，

to form new memories of facts or events, but, he was still able to remember things he had learned before the surgery.

對於真相或事件他沒辦法形成新的記憶，但，他還能記得手術以前學過的事物。

This showed us that the hippocampus is a key to making memories, but that it isn't where memories are stored.

這顯示出海馬迴是製造記憶的關鍵，但不是記憶儲存的地方。

So how do experiences become memories?

所以經歷要怎麼變成記憶呢？

If we look inside the brain of a mouse in a maze, we could

如果我們觀察在迷宮中的老鼠的大腦，

draw a kind of map, showing which brain cells are active as the mouse experiences something [mouse in maze].

我們可以畫出一幅地圖，顯示老鼠經歷了某些事的時候，哪個腦細胞會開始活動 (老鼠在迷宮中)。

Later, we would see the mouse's brain cells firing in the same patterns,

之後，我們就會看到老鼠的腦細胞以相同的形式激發，

replaying the experience in fast forward, over and over,

一遍又一遍將經歷不斷快轉重播，

backwards and forwards, to make the connections between cells stronger.

倒帶又前進，讓細胞間的連結更加緊密。

This is called consolidation, and it's how animals - including humans - commit new memories to long-term storage.

這稱作 (記憶) 鞏固，這就是動物——包括人類——將新記憶牢記後形成長期記憶儲存的過程。

Days or weeks later, a smell might trigger this same pattern of cells nerve firing in

數天或數周後，某個味道可能會觸發老鼠大腦內同樣形態的細胞神經激發，

the mouse brain, a recall of the maze memories - just like smelling cinnamon might trigger memories of grandma for you.

讓老鼠回憶起迷宮的記憶——就像你聞到肉桂味可能會觸發對於祖母的回憶一樣。

But the brain's way of creating memories isn't foolproof.

但大腦創造記憶的方法並不是如此簡單的。

Sometimes, our mental replay of something we only imagined can feel as vivid as a real experience.

有時候，我們在腦中不斷重播一些只是想像出來的事物，也會感覺像真實經歷一樣生動。

If you picture all the sights, smells, and sounds of a crime scene from someone's description,

如果你從某人的敘述中想像犯罪情境中所有的景象、味道與聲音，

you activate similar brain networks as if you had really been there.

你的大腦網絡會活動得好像你真的去過那裏一樣。

The more you replay the scene in your mind, the more it feels like a real memory.

你在腦海中重播這個場景越多次，就感覺越像真的記憶。

That's why a detective who asks leading questions can inadvertently plant a false memory in a witness.

那就是為什麼一個警探問引導性問題時會不經意地在目擊者腦中植入錯誤的記憶。

We're able to remember a lot, but we forget even more.

我們可以記得很多，但我們忘記得更多。

Some forgetting just happens, but our brains also forget on purpose.

有些就是碰巧忘了，但我們的大腦也會有意地忘記事物。

We have at least three different ways of forgetting.

我們至少有三種遺忘的方法。

The first is what happens when a memory fades over time, so-called “passive oblivescence”(a term you will probably forget).

第一個是記憶隨著時間流逝而淡去，就是所謂的「被動遺忘」(一個你可能會忘記的詞)。

This may happen because the connections between brain cells gradually weaken over time;

因為腦細胞之間的連結隨著時間逐漸弱化時，可能就會發生這個現象；

or perhaps the memory is still there, but you might lose the triggers–sights, sounds,

或是也許記憶還是在，但你失去觸發來源 —— 場景、聲音

smells–you need to retrieve it.

味道——你需要找回來。

Another idea says memories could theoretically last forever, but when the same neurons get

其他意見則表示記憶理論上可以永久存在，但當相同的神經元被用在其他記憶上時，

used in other memories, this “interference” disrupts the original memory.

這樣的「干擾」會破壞原有的記憶。

This slow fade type of forgetting happens to all of us, eventually.

最終這種緩慢逝去的遺忘型態會發生在我們所有人身上。

A second type of forgetting–targeted forgetting–happens at night while we sleep.

第二種遺忘型態——目的性遺忘——會在我們夜晚睡覺時發生。

This is when we clear out random, useless tidbits of information we've learned during the day and erase outdated memories.

這是當我們清除白天學習到的隨機、無用的小知識，以及抹去陳舊的記憶時會發生的遺忘形態。

For example, if yesterday, you thought Earth was, say, a flat disk supported by three elephants,

舉例來說，如果昨天，你覺得地球是，這麼說好了，一個由三隻大象支撐的光碟圓盤狀的，

and today you learned that the Earth is round, your brain needs to purge one of these contradictory ideas - hopefully, the one about the elephants.

而今天你知道地球是圓球狀的，你的大腦就需要清除這些矛盾想法中的其中一個——希望是有大象的那一個。

In certain stages of sleep, we trim and prune connections between cells and erase unneeded memory circuits.

在某個睡眠階段，我們會修整、刪除細胞之間的連結，並清除不需要的記憶迴路。

The third type of forgetting is motivated forgetting, something we all wish we could do for one thing or another.

第三種遺忘形式是動機性遺忘，我們都希望我們可以忘記某些事。

This is when a person intentionally suppresses unpleasant memories.

這是當一個人有意地要抑制不愉快記憶時發生的。

Forgetting on purpose is a way to regulate our emotions and to focus on what needs to

有意圖的遺忘是一種調整我們的情緒的方式，還有讓我們專注在當前我們需要完成的事情上，

be done in the present, instead of getting lost in negative memories of the past.

而不是迷失在過去負面記憶當中。

We may need motivated forgetting to maintain our self-image, to maintain confidence, to

我們可能需要動機性遺忘來保持自我形象、維持自信、

stay optimistic about the future, or to be able to maintain relationships with people who have hurt us.

對未來保持樂觀、或是能夠與傷害我們的人保持關係。

We don't know exactly how motivated forgetting happens, but part of our brain seems to step

我們不知道動機性遺忘確切是怎麼發生的，但我們的大腦有部分似乎

in and block the troubling memory from being retrieved.

介入並阻止我們回想起令人煩惱的記憶。

So that even though it's still somewhere in our brain, eventually we can't find it.

所以即使記憶還在我們大腦中的某處，我們最終還是找不到它。

Our brains have so many ways to forget because forgetting is one of the most important things we do.

我們的大腦有很多方法去遺忘，因為遺忘是我們所做的最重要的事情之一。

Forgetting allows us to move past traumatic life events.

遺忘讓我們移除過去痛苦難忘的人生事件。

In fact, PTSD may be a problem where someone simply remembers too much.

事實上，創傷後壓力症候群 (Post-traumatic stress disorder，簡稱 PTSD)，可能就只是某個人記得太多事情。

Forgetting also allows us to clear out junk.

遺忘也能讓我們把腦中無用的資訊清除。

Imagine every sight, sound, smell, and piece of information your brain processes every day!

想像你的大腦每天都要處理的每個場景、聲音、味道與片段的資訊。

If our brains didn't sweep out the garbage every night, we would soon overflow our neural

如果我們的大腦沒有每天晚上把垃圾掃除，我們的神經元網絡很快就會

networks with random useless trivia, just like Sherlock Holmes predicted.

被隨機無用的瑣事給塞爆，就像 Sherlock Holmes 預言的那樣。

We also wouldn't be able to replace things that are no longer true with better information and update our mental models of the world.

我們也沒辦法用更好的資訊取代不再正確的事物，還有更新我們腦中對這個世界的模型。

Deep in the scientific literature we find stories of a handful of people who NEVER forget anything.

深入發掘科學文獻可以發現一些從未忘記任何事物的人的故事。

They are so rare that their unforgetfulness has a medical name: hyperthymesia.

他們無法忘記任何事的能力太罕見了，這個症狀在科學上稱為：超憶症。

The most famous case is Jill Price, an American woman now in her fifties.

最有名的案例就是 Jill Price，一位現今五十幾歲的美國女性。

Starting from age 14, Jill's memory of her life is nearly perfect.

從 14 歲開始，Jill 對她自己人生的記憶近乎完美無缺。

For any date in the past, she remembers what she wore and had for lunch that day, key historical

她記得過去任何一天的穿著、那天午餐吃甚麼、她有注意到的關鍵歷史事件，

events that she paid attention to, and detailed incidents from her life.

還有她人生事件的詳細內容。

She describes memories playing in her mind in vivid detail like a video reel that has

她描述記憶就像盤式錄影帶一樣在她腦海中播放出生動的細節，

been enhanced with smells and emotions, whether the events occurred yesterday or decades ago.

這些記憶透過嗅覺與情緒強化後更加深刻，無論是昨天或數十年前發生的。

This might sound like a blessing, especially if you're in school, but Jill has described

這聽起來似乎是個好事，特別是你如果還在學校，但 Jill 曾說

being haunted by upsetting memories and by regrets, because unlike the rest of us, she

心煩意亂的記憶與懊悔不斷困擾著她，因為不像我們一樣，

can clearly remember every choice she made and how it turned out.

她可以清楚地記得她做的每個選擇與結果。

There's probably something you truly ''want'' to forget, like that extremely embarrassing

或許有些事是你真的「想要」忘記，像是高中那些超級尷尬的時刻，

moment in high school that always seems to pop up at the worst times.

這樣的記憶總是會在最糟糕的時刻冒出來。

Can we erase those unwanted memories somehow?

我們能稍微清除掉那些不想要的記憶嗎？

In an episode of House, MD, Dr. House treated a patient suffering from painful memories

在某一集《怪醫豪斯》中，House 醫生為了治療一位受痛苦記憶困擾的病人，

by performing something called electroconvulsive therapy: controlled electric shocks to the brain.

他進行了所謂的電療法：控制電流來衝擊大腦。

People who undergo ECT do lose some memories – only not necessarily the ones they hope.

經歷電療法 (Electroconvulsive therapy，簡稱 ECT) 的人確實失去了一些記憶——只是不一定是他們希望的那個。

When it comes to erasing memories in humans, our best tool still works like a hammer, not a scalpel.

當要清除掉人類的記憶，我們最好的工具還是像槌子一般，而不是手術刀。

It's no accident that our ability to forget, like our ability to remember, is a complex and finely-tuned mechanism.

我們遺忘的能力就像我們記憶的能力一樣，是複雜且經過微調的機制，而非偶然的。

If humans couldn't remember and learn from important events, our species probably wouldn't have survived.

如果人類沒辦法從重要事件中記憶與學習，我們這個物種可能不會存在。

But it seems that being able to forget is just as critical, an elementary part of solving this great mystery we call life.

但能夠遺忘似乎同樣重要，這是我們解決人生這個巨大謎團的基本要素。

Stay curious!

保持好奇心！

So you probably can't teach yourself to have perfect memory, and never forget anything.

所以你可能沒辦法傳授你自己擁有完美的記憶力，還有從不忘記任何事。

Not without a massive brain injury or something.

如果沒有嚴重的腦損傷或甚麼的話。

But is memorization really the best way to learn something?

但背誦真的是學習的最佳方法嗎？

Memorizing can definitely help you get started with a new concept.

記憶確實可以幫助你開始學習一個新的概念。

However, truly understanding it requires much more - seeing how concepts are related to

然而，真正了解它還需要更多工作——了解概念間如何互相連結、

each other, looking for different interpretations, dealing with new information.

找尋不同的解釋、處理新的資訊。

These are the skills that will help you learn anything, and if you'd like to sharpen your

這些事幫助你學習任何事物的技能，而你如果想要精進你的大腦

brain and develop these tools, then Brilliant could be the place to go for that.

並發展這些工具，那麼 Brilliant 就會是個好地方。

Check out this Brilliant course on logic and deduction.

去看看這個 Brilliant 的邏輯與推論課程。

It's got fun and challenging riddles and mind-benders, broken up into bite size pieces,

它充滿有趣、挑戰性謎語以及腦筋急轉彎，分成很多小單元，

and they'll guide you through the problems until you're a Sherlock Holmes-level logical thinker…

並且透過這些問題引導你，直到你成為一個 Sherlock‧Holmes 等級的邏輯思想者 ...

To support It's Okay To Be Smart and learn more about Brilliant, go to brilliant dot

如果要支持 It's Okay To Be Smart 頻道，還有了解更多 Brilliant 的內容，

org slash BESMART and sign up for free.

請前往 brilliant.org/BESMART，並免費登入。

And also, the first 200 people that go to that link will get 20% off the annual Premium subscription.

還有，前 200 名前往這個連結的人可以得到高級訂閱 8 折優惠。