Hucksters promise to unlock that hidden potential with methods "based on neuroscience", but all they really unlock is your wallet.

推銷的人承諾讓你透過「有神經科學根據」的方法解鎖潛能，但他們解鎖的不過是你的錢包。

Two-thirds of the public and nearly half of science teachers mistakenly believe the 10% myth.

三分之二的大眾和近半的科學老師都誤信了這 10% 迷思。

In the 1890s, William James, the father of American psychology, said, "Most of us do not meet our mental potential."

1890 年代時，美國心理學之父威廉‧詹姆士說：「我們多數人都未充分發揮心智潛能。」

James meant this as a challenge, not an indictment of scant brain usage, but the misunderstanding stuck.

詹姆士的用意在於給予挑戰，而不是在譴責缺乏用腦，但這誤解延續至今。

Also, scientists couldn't figure out for a long time the purpose of our massive frontal lobes or broad areas of the parietal lobe.

此外，科學家長久以來都搞不清楚人類巨大額葉或大面積頂葉的功能為何。

Damage didn't cause motor or sensory deficits, so authorities concluded they didn't do anything.

損傷並不會造成運動或感覺障礙，所以科學家斷定它們沒有任何用處。

For decades, these parts were called silent areas, their function, elusive.

數十年來，這些部分被稱為 「寂靜區域」，它們的功能難以描述。

We've since learned that they underscore executive and integrative ability, without which we would hardly be human.

我們此後得知它們強調執行及整合能力，沒有它們，我們便稱不上是人類。

They're crucial to abstract reasoning, planning, weighing decisions, and flexibly adapting to circumstances.

它們對於抽象推理、計畫、衡量決策及對各種情況的適應力都至關重要。

The idea that nine-tenths of your brain sits idly by in your skull looks silly when we calculate how the brain uses energy.

如果我們計算腦部如何使用能量，「大腦有十分之九在顱腔內閒著」這個想法會顯得很愚蠢。

Rodent and canine brains consume 5% of total body energy.

齧齒類及犬類的腦消耗身體總能量的 5%。

Monkey brains use 10%.

猴子的腦使用 10%。

An adult human brain, which accounts for only 2% of the body's mass, consumes 20% of daily glucose burned.

一個成年人的腦只占身體總質量的 2%，卻消耗每日燃燒葡萄糖量的 20%。

In children, that figure is 50%, and in infants, 60%.

對應到孩童的數字是 50%、嬰兒則是 60%。

This is far more than expected for their relative brain sizes, which scale in proportion to body size.

腦容量與身體大小成正比，因此就他們相對的腦容量而言，這比預期高出許多。

Human ones weigh 1.5 kilograms; elephant brains, 5 kilograms; and whale brains, 9 kilograms.

人類腦重 1.5 公斤、大象腦重 5 公斤，而鯨魚腦則是 9 公斤。

Yet, on a per-weight basis, humans pack in more neurons than any other species.

然而單以重量比來看，人腦轉載的神經元比其它物種都還要多。

This dense packing is what makes us so smart.

這種高密度填充的神經元就是人類如此聰明的原因。

There is a trade-off between body size and the number of neurons a primate, including us, can sustain.

包含人類在內的靈長類動物必須在體型和能維持多少神經元間取得平衡。

A 25-kilogram ape has to eat 8 hours a day to uphold a brain with 53 billion neurons.

一隻 25 公斤的人猿每天要進食 8 小時以維持腦內 5 百 30 億個神經元。

The invention of cooking one-and-a-half million years ago gave us a huge advantage.

人類在 150 萬年前發明的烹飪給予人類一項巨大優勢。

Cooked food is rendered soft and predigested outside of the body.

煮熟的食物會變軟且已在身體外預先消化了。

Our guts more easily absorb its energy.

我們的腸胃更容易吸收它的能量。

Cooking frees up time and provides more energy than if we ate foodstuffs raw, and so we can sustain brains with 86 billion densely-packed neurons, 40% more than the ape.

比起生吃食物，烹調能讓我們空出時間，並提供更多能量，我們也才能維持腦內比人猿多出 40% 的 8 百 60 億個緊密填充的神經元。

Here's how it works.

這是它運作的方式。

Half the calories a brain burns go towards simply keeping the structure intact by pumping sodium and potassium ions across membranes to maintain an electrical charge.

大腦燃燒的半數卡路里用來維持其結構穩固，並透過抽送鈉、鉀離子通過細胞膜來維持電荷。

To do this, the brain has to be an energy hog.

要這樣做，大腦必須是個耗能大戶。

It consumes an astounding 3.4 x 10^21 ATP molecules per minute, ATP being the coal of the body's furnace.

它每分鐘消耗驚人的 3.4 x 10^21 個三磷酸腺苷分子（ATP），而 ATP 則是人體能源火爐的煤炭。

The high cost of maintaining resting potentials in all 86 billion neurons means that little energy is left to propel signals down axons and across synapses, the nerve discharges that actually get things done.

要讓 8 百 60 億個神經元都維持靜止電位的成本很高，這表示只剩下很少的能量能將信號推送到軸突、越過突觸，也就是實際完成事情的神經放電。

Even if only a tiny percentage of neurons fired in a given region at any one time, the energy burden of generating spikes over the entire brain would be unsustainable.

即使只有極少百分比的神經元在任一時段的任一某個區域被激發，要在整個大腦產生電衝動需要負擔的能量也是無法持續的。

Here's where energy efficiency comes in.

這就是能量效率派上用場的地方。

Letting just a small proportion of cells signal at any one time, known as sparse coding, uses the least energy but carries the most information because the small number of signals have thousands of possible paths by which to distribute themselves.

只讓一小部分的細胞在某一段時間發送信號，稱為「稀疏編碼」，也就是用最少的能量，但傳遞最多的訊息，因為這些少數信號可以用數千種可能的路徑來散發出去。

A drawback of sparse coding within a huge number of neurons is its cost.

在大量的神經元內進行稀疏編碼有個缺點，就是成本很高。

Worse, if a big proportion of cells never fire, then they are superfluous, and evolution should've jettisoned them long ago.

更糟的是，如果有很大比例的細胞從未活躍，那麼這些細胞就是多餘的，演化早該在很久以前就拋棄它們了。

The solution is to find the optimum proportion of cells that the brain can have active at once.

解決的方法就是找出大腦可以一次激發的最佳細胞比例。

For maximum efficiency, between 1% and 16% of cells should be active at any given moment.

應該要有介於 1% 到 16% 間的細胞在任一時刻處在活躍狀態，這是能量的限制。

This is the energy limit we have to live with in order to be conscious at all.

為了保持意識，我們不得不接受能量限制。

The need to conserve resources is the reason most of the brain's operations must happen outside of consciousness.

因為要保存資源，所以大部分的腦部運作都必須發生在意識之外。

It's why multitasking is a fool's errand.

這就是為什麼多工只會徒勞無功。

We simply lack the energy to do two things at once, let alone three or five.

我們就是沒有精力同時做兩件事，別說 3 件或 5 件事了。

When we try, we do each task less well than if we'd given it our full attention.

當我們試著多工，我們每件事的成效都比只專心做一件事要差。

The numbers are against us.

數量對我們不利。

Your brain is already smart and powerful, so powerful that it needs a lot of power to stay powerful, and so smart that it has built in an energy efficiency plan.

你的大腦已經很聰明、威力強大，如此強大，它需要很多能量以保持強大，而且是如此聰明，它已經內建了一個節能計畫。

So, don't let a fraudulent myth make you guilty about your supposedly lazy brain.

所以不要讓一個不實的傳說讓你對可能懶惰的大腦感到愧疚。

Guilt would be a waste of energy.

愧疚會浪費能量。

After all this, don't you realize it's dumb to waste mental energy?

在這長篇大論之後，你難道還不明瞭浪費心智能量是件很蠢的事？

You have billions of power-hungry neurons to maintain, so hop to it!

你有數十億餓的要命的神經元要維持，所以快點上工吧！