Gurus and life hackers make a living telling us how to get better at it.

印度教宗師和生活駭客以告訴我們該如何更好地面對生活維生。

But can we actually multitask?

但我們真的能一心多用嗎？

The term was first used in the '60s, to describe computer performance.

multitask 這個詞首次在 1960 年代出現，用來形容電腦的性能。

The human brain, though, is not a computer and human attention is a very limited resource.

但是人腦並非電腦，人類的注意力是有限的。

Some psychologists model visual attention as being like a spotlight.

許多心理學家用模型展示，發現視覺注意力就像是一個聚光燈。

It can only be shone in one direction at any one time.

一次只能把光投往一個方向。

Our primary focus - what we're paying most attention to - is like the brightly lit area in the centre of the beam.

我們主要的焦點——最關心的事物，就像是光束中心照亮的區域。

It can also be understood as being like a zoom lens - we can choose to narrow our focus to concentrate in detail, or widen it, to be aware of more things simultaneously.

也可以理解成變焦鏡頭，我們可以選擇縮小焦點，專注在細節上，或是放寬焦點，同時注意更多事情。

But we can't be zoomed in and out at the same time.

但是我們無法同時放大和縮小。

Even though we're constantly receiving a huge amount of information from our senses, it's only possible for a small amount to make it through to conscious awareness.

儘管我們不斷的從感官中接收龐大的訊息，只有一小部份的訊息可以變成自覺意識。

Watch the next section very carefully, and pay particular attention to how many balls bounce in the circle.

仔細地看以下的畫面，特別注意圓圈中有幾顆球在跳。

How many can you count?

你數了幾顆球？

Seven, right?

7 顆，對嗎？

But did you also notice that little dinosaur?

但你有注意到畫面中有一隻小恐龍嗎？

What about the changing shape of the circle?

有注意到圓圈的形狀改變嗎？

Or the smiley face on one of the balls?

或是其中一顆球上的笑臉？

This shows just how powerful focused attention is.

這顯示了專注力有多強大。

Being able to filter out irrelevant detail is an amazingly useful tool, but it means we can miss things that are right under our noses - an effect known as inattention blindness.

可以過濾掉不相關的細節很驚人且有用，但也代表我們可能錯過眼前的事物，這個現象稱作「不注意視盲」。

You can see this very clearly in the famous Invisible Gorilla experiment.

你可以在著名的「看不見得猩猩實驗」中，清楚地看見這個例子。

When asked to concentrate exclusively on how often basketball players in white pass the ball, most people completely miss the gorilla walking across the screen and beating his chest.

當被要求只專注在穿著白衣的籃球選手，注意他們傳球頻率時，大多數人徹底忽略穿越螢幕並搥胸的猩猩。

We just don't have the capacity to process everything at once.

我們沒有能力一次處理所有事。

This is a particular problem when we try to multitask.

這也是在我們試著一心多用時的問題。

We can switch attention from one task to another and back again.

我們可以在任務之間切換注意力。

But when attention is overloaded, we miss things, and the result is nearly always that we perform tasks less well than we would doing them one at a time.

但當注意力超載時我們會錯過事物，與一次做一件事時相比，我們一心多用的結果通常是表現得不太好。

It's only truly possible to do two things at once if they require different sets of cognitive resources.

只有當認知的來源不同時，才可能同時做兩件事。

For example, it's totally possible to read a book and listen to music at the same time.

舉例來說，邊讀書邊聽音樂是絕對可行的。

Which would suggest that driving while talking on the phone is not a problem, as long as it's a hands-free phone.

這暗示著只要使用免持手機，邊開車邊講電話也不成問題。

It's not that simple though.

但這件事沒那麼容易。

Research has shown that while talking on the phone, we have a tendency to create mental images, and this uses the same visual resources needed for driving.

研究顯示，在講電話時我們易於製造心理影像，而這與開車時所使用的視覺資源相同。

And if visual resources become too stretched, it's perfectly possible for a driver to look directly at a hazard but, just like with that little dinosaur, fail to see it.

但如果視覺資源延伸得太長，駕駛極有可能直接注視著危險卻不知道，跟看不到小恐龍是一樣的道理。

Not everything will make it through to conscious awareness.

不是所有事物都會成為自覺意識。

So multitasking makes us at best, inefficient, and at worst, downright dangerous.

所以一心多用說好聽點是讓我們沒有效率，往難聽點是十分危險的。

If you're feeling like you should be doing 17 things at once, remember, that's just not the way your brain is wired.

如果你覺得你一次應該做 17 件事情，記住，我們的大腦不是以這樣的方式連結。

Thanks for watching.

感謝收看。

Don't forget to subscribe and click the bell to receive notifications for new videos.

記得訂閱頻道並按下小鈴鐺接收最新的影片消息。

See you again soon!

再見！