That may sound like a huge waste of time, but scientists think it must have some purpose, or humans wouldn't have evolved to do so much of it.

這聽起來像是在浪費時間，但科學家們認為這一定是有目的的，否則人類就不會進化到可以做這麼多白日夢。

So to figure out what's going on here, let's take a closer look at the mind-wanderer in chief: the bored teenager.

所以要弄清楚發生了什麼，讓我們仔細看看主要的思想流浪者：無聊的少年。

Wouldn't it be cool to discover something, anything? Like even this plant.

去發掘一些東西，任何東西，應該會很酷吧。甚至去了解這個植物。

Just to be one of those explorers who sails around drawing stuff for years on end and everyone thinks they're a genius.

成為那些連續多年在繪畫中航行的探險家之一，每個人都認為他們是天才。

But does anyone even do that anymore?

但現在還有人這樣做嗎？

Is there anything left to discover?

還有什麼可以去發掘的嗎？

And would I be tough enough to deal with the dysentery or scurvy or piranhas or whatever?

我是否會足夠堅強來應對痢疾、壞血病或食人魚或其他什麼嗎？

I barely have the endurance to make it through track practice... but I will.

我根本沒什麼耐力通過田徑練習……但我會的。

Any day now, I'll have the discipline to show up before sunrise and practice.

現在任何一天，我都會有紀律地在日出前出席並練習。

I'll win all my races.

我將贏得我所有的比賽。

Winning will become so easy, I'll pick up other events just for fun.

贏得比賽將變得輕而一舉，我會參加各種比賽就為了好玩而已。

And once I'm in the Olympics, they'll have no choice but to crown me, team captain, which I will graciously accept.

一旦我參加奧運會，他們別無選擇，只能為我，也就是隊長加冕，而我會欣然接受。

And will I be nasty to the teammate who yelled at me? No.

而我會不會欺負罵我的隊友？ 不會。

I'll just calmly say, "Hope you're in a better mood."

我會平靜地說，「希望你的心情會好一點。」

Okay. Yours and other people's daydreams might sound or feel something like that.

好喔。你和其他人的白日夢可能聽起來或感覺像這樣。

Let's see what was going on.

讓我們看看發生了什麼事。

To see what parts of the brain are active when you're doing a task, or thinking, or daydreaming,

為了看出你在執行任務、思考或做白日夢時，大腦的哪些部分是活躍的，

scientists use brain imaging techniques that show increased blood flow and energy expenditure in those areas.

科學家使用大腦成像技術顯示這些區域的血流量和能量消耗增加。

These brain areas are active, working together and communicating with each other.

這些大腦區域是活躍的，一起運作並相互交流。

Taken together, they're called the executive network.

合在一起，它們被稱為執行網絡。

When your mind starts to wander, a different set of brain areas becomes active.

當你的思緒開始走神時，一組不同的大腦區域就會變得活躍。

These areas make up the default mode network.

這些區域構成預設模式網絡。

The name default mode makes it sound like nothing is going on.

預設模式這個名稱聽起來像是什麼都沒有發生。

And in fact, for many years, scientists associated this pattern of activity with rest.

事實上，多年來，科學家們將這種活動模式與休息聯繫在一起。

But a closer look reveals that these are the brain areas involved when we revisit a memory, when we think about our plans and hopes,

但仔細觀察會發現，當我們重溫一段記憶、當我們思考我們的計劃和希望時，這些是涉及的大腦區域，

and yes, when our minds are wandering off on a wild daydream.

當然，還有當我們的思緒瘋狂的走神到白日夢時。

The mind can wander to unproductive or distressing places and brood over negative past events, like an argument.

頭腦可能會走神到沒有生產力或令人痛苦的地方，並沉思過去的負面事件，比如爭執。

It can also wander to neutral, everyday matters, like planning out the rest of one's afternoon.

它也可以走神在中立的日常事務上，像是計劃下午的剩餘時間。

But where mind-wandering really gets interesting is when it crosses into the realm of free-moving associative thought that you aren't consciously directing.

但是，走神真正變得有趣的地方是，當它進入你沒有有意識地引導的自由移動的聯想思想領域時。

This kind of mind-wandering is associated with increases in both ideas and positive emotions,

這種走神與點子和正面情緒的增加有關，

and the evidence suggests that daydreaming can help people envision ways to reach their goals and navigate relationships and social situations.

有證據表明，白日夢可以幫助人們設想實現目標的方法，並駕馭人際關係和社交場合。

Scientists think there may be two essential parts to this process:

科學家們認為這個過程可能有兩個基本部分：

a generative phase of free-flowing ideas and spontaneous thoughts, courtesy of the default mode network,

由預設模式網絡提供的自由流動的想法和自發思想的生成階段，

followed by a process of selecting, developing, and pursuing the best ideas from that generative burst,

接下來是從那次生成性爆發中選擇、發展和追求最佳想法的過程，

driven by logical thinking, thanks to the executive network.

由邏輯思維驅動，這要歸功於執行網絡。

A host of imaging studies suggest that these two networks working in sync is a crucial condition for creative thinking.

大量成像研究表明，這兩個網絡同步運作是創造性思維的關鍵條件。

Taken together, the evidence clearly suggests the logical realm of the executive network and the imaginative realm of the default mode network are closely related.

綜上所述，證據清楚地表明執行網絡的邏輯領域和預設模式網絡的想像領域密切相關。

And as you can see, the executive network is still playing a role when the default mode network is doing its thing during daydreaming.

正如你所看到的，當預設模式網絡在做白日夢時，執行網絡仍在發揮作用。

In teenagers, the prefrontal cortex and other areas involved in executive function are still developing,

在青少年中，前額葉皮層和其他涉及執行功能的區域仍在發育，

but teens are perfectly capable of thinking through their problems and goals, especially when given space to do so on their own.

但青少年完全有能力思考他們的問題和目標。特別是在給他們自己提供空間的情況下。