When are you actually an adult? - Shannon Odell

譯者: 穎君 紀 審譯者: Shelley Tsang 曾雯海

Most countries recognize 18 as the start of adulthood

多數國家視 18 歲為成人期的起點，

by granting various freedoms and privileges.

賦予 18 歲以上的人們許多自由和特權。

But is age the best way to measure maturity?

但年齡真的是測量成熟度最佳的工具嗎？

I was born 12:05 AM on November 6th—

- 我出生在 11 月 6 日凌晨 0 點 5 分—

5 minutes short of being eligible to vote in the election tomorrow.

只差五分鐘，就能參與明天的投票。

Meanwhile, your big brother— yours truly—

- 而我呢，你大哥—真的是你哥—

was born 15 minutes earlier, so I can vote.

比你早 15 分鐘出生，所以我可以投票。

It’s arbitrary and unfair!

- 太隨便了吧！不公平！

The voting age should be lowered to 16!

投票年齡應該降到 16 歲！

I firmly disagree!

- 我堅決反對！

No way 16-year-olds are mature enough to make decisions with national consequences.

16 歲的人不可能成熟到可以做出 攸關國家的決定，

I’m eligible and I don’t even know who’s running.

我符合投票資格， 都不知道是誰要選了。

Meanwhile, I know the candidates inside and out.

- 我呢，對候選人們的資訊都一清二楚。

She's obsessed with politics.

- 她是政治狂熱份子。

Exactly! If 16-year-olds aren’t mature enough to vote,

- 我就是！如果 16 歲的人沒有 成熟到可以投票，

then by that same logic, they shouldn’t be allowed to drive.

根據這邏輯，他們也不能開車囉！

I firmly disagree! I’m an excellent driver!

- 我堅決反對！我很會開車！

And I’ve never gotten a ticket, unlike some people.

我沒被開過罰單，哪像「某人」。

That’s so unfair! That stop sign was hidden by a tree.

- 不公平！那個停止標誌被樹擋到了欸！

I think you both make valid points.

我覺得你們兩個的意見都有道理。

And questioning the age limits of adulthood is well warranted.

懷疑成年人的年齡界定也是很正常的事。

Some countries have lowered the voting age to 16,

有些國家降低投票年齡到 16 歲，

and cultural coming-of-age ceremonies are often celebrated at different ages.

各文化裡成年禮所慶祝的歲數也不盡相同。

As there seems to be no consensus on exactly when we reach maturity,

既然在幾歲才叫「成人」的問題上 似乎沒有共識，

perhaps science can give us a clearer answer.

那或許科學能給我們更清楚的答案。

One way neuroscientists have looked to define adulthood

神經學家試著界定「成人」的 其中一種方法

is by when the brain is fully grown.

是看腦部何時發展完全。

Brain development involves two trajectories.

腦部發展包括兩個方向：

First, there's a reduction in gray matter.

第一，灰質會減少。

Gray matter consists of cells and connections

灰質由細胞和神經連結組成，

that facilitate communication at short ranges,

這些連結能夠在短距離內溝通，

creating dense, information-processing hubs.

形成密集處理資訊的區塊。

While a reduction may seem like a bad thing,

雖然「減少」看似負面，

what’s happening is a selective pruning.

但這其實跟修剪枝葉同一個道理：

Connections that are used are kept and strengthened,

常用到的連結會被保留、強化，

while under-used ones are weeded away,

不常用的就被廢棄、清除，

creating a brain that is both fine-tuned to its environment and energy efficient.

打造出既符合環境需求又節能的大腦。

This gray matter reduction coincides with an increase in white matter.

在灰質減少的同時，白質會變多。

White matter refers to connections that are myelinated,

白質指被髓鞘包裹住的神經連結，

coated in a layer of insulation,

髓鞘的絕緣性質

allowing for fast far-range communication between information hubs.

讓資訊處理區塊間溝通得更快， 訊號傳遞得更遠。

For example, these paths connect regions that signal

例如，這些路徑連結了

the pleasure of immediate reward with regions that help us plan ahead,

得到立即獎勵後感到快樂的區域， 和幫我們提前做計畫的區域，

allowing us to make more balanced, forward-thinking decisions.

讓我們做出更有遠見的決定。

Imaging studies show that white and gray matter volumes

神經成像研究顯示 灰質和白質的體積

undergo drastic changes during adolescence,

在青春期時會劇烈改變，

and continuing through your twenties.

一路持續到二十幾歲。

But the brain’s journey is far from finished,

但腦部發展的歷程還遠遠不及結束，

as various experiences continue to reshape its connections

因為你人生中的經驗 會持續重塑大腦連結，

throughout your lifetime.

So brain structure alone may not give us our answer.

所以腦部結構沒辦法幫我們回答問題。

Another way scientists have tried to define adulthood

另一種科學家試定義成人的方式是

is by measuring cognitive development—

測量認知發展：

when are you able to learn and complete mental tasks

你何時能和年長的成人以同樣效率 學會，及完成心理任務？

at the same efficiency as older adults?

By this definition, adulthood may begin as early as 16,

以這個定義， 成人的門檻可以早至 16 歲，

as teens perform just as well on tests

因為青少年們在

that assess reasoning, problem-solving and critical thinking.

推理、解決問題及批判性思考的 測驗中都表現得不錯。

Though capable of making smart, well-informed decisions,

雖然青少年能做聰明、周詳的決策，

teens may be more susceptible to external pressures.

但是他們更容易被外部壓力左右。

Studies show that when performing risk- taking and self-control related tasks,

研究顯示，在處理冒險、自我控制 相關的任務時，

18 to 21 year olds behave much like older adults.

18 到 21 歲的人表現得 很像年長的成人，

But when these tests include an emotional element—

但如果測驗包含情緒這個要素，

such as utilizing self-control when identifying fearful faces—

像是一邊辨識恐懼表情， 一邊處理自我控制的任務，

or a social element—

或是社會性要素，

such as making a decision in the presence of a friend—

像是在有朋友在場的場合做決定，

different patterns emerge.

就會有不同的結果。

Under these influences, 18 to 21 year olds tend to behave more like younger teens,

在這些影響下，18 到 21 歲的人 就表現得比較像年輕人，

and their brains show younger-teen-like patterns of activity.

且他們的大腦活動也較接近年輕青年。

In other words, during your teens and early twenties,

換句話說，在青少年及二十出頭時，

your brain is wired to place more value and attention

你的大腦本來就會更加重視

on social and emotional elements.

社會及情感層面的要素，

This allows emerging adults to better explore their identities

這讓即將成人的青年們 能夠探索各種身份認同、

and connect with others,

與他人產生聯繫，

but may also create more vulnerability to negative peer influence

但也可能讓青年們更容易受負面同儕影響、

and rash heat of the moment decisions.

做出太急躁的決定。

For this reason, many scientists argue that judicial systems

因此，許多科學家認為司法系統應當

should expand juvenile courts to include

讓少年法庭受理的年齡

those in their late teens and early twenties,

開放至接近二十歲及二十出頭，

as current systems fail to recognize

因為現在的系統無法認知

how the emerging adult brain is still changing.

即將成人的人們，他們的大腦仍在變化的事實。

So when are you actually an adult?

那麼，你要長到幾歲才算成人呢？

As you can see, there is no exact age or moment

如你所見，在大腦發展的過程中， 沒有清楚的年齡或瞬間能夠界定成人。

in development that we can point to.

Instead, neuroscience suggests that there are waves of maturity.

取而代之，神經科學家提出腦的發展梯次。

As different brain regions and mental abilities mature at different times,

腦的各區塊和各種心理能力 成熟的時間點都不盡相同，

so do different adult-like states and behaviors.

「有成人樣子」的各種心理狀態和行為 也亦然。

Not everyone will reach each wave of maturity at the same age.

大家踏入每個成熟梯次的年齡都不盡相同。

Each person’s journey to adulthood is unique,

每個人成人的路途都獨一無二，

influenced by genetics, environment, and experience.

被基因、環境，和經驗形塑。