Camera or eye: Which sees better? - Michael Mauser

眼睛 vs. 相機 - Michael Mauser

譯者: Huan-Yu Hsieh 審譯者: Marssi Draw

Watch the center of this disk.

請看轉盤的中心。

You are getting sleepy.

你開始覺得睏。

No, just kidding.

開玩笑的，

I'm not going to hypnotize you.

我沒有要催眠你。

But are you starting to see colors in the rings?

不過你開始看到圓圈的色彩了嗎？

If so, your eyes are playing tricks on you.

如果看得到， 表示你的眼睛正在捉弄你。

The disk was only ever black and white.

轉盤從頭到尾都是黑白的。

You see, your eyes don't always capture the world as a video camera would.

你看，你的眼睛並不總是 像攝影機一樣捕捉世界。

In fact, there are quite a few differences,

事實上，兩者有許多不同，

owing to the anatomy of your eye

歸因於眼睛的構造，

and the processing that takes place in your brain

以及大腦裡的處理過程，

and its outgrowth, the retina.

和它的發展結果──視網膜。

Let's start with some similarities.

我們先來看一些相似之處。

Both have lenses to focus light and sensors to capture it,

兩者都有鏡頭可以對光線聚焦， 還有感光元件捕捉光線，

but even those things behave differently.

但作用方式很不一樣。

The lens in a camera moves to stay focused on an object hurtling towards it,

相機鏡頭以移動 對投擲過來的物體對焦，

while the one in your eye responds by changing shape.

而眼睛的反應方式則是改變形狀。

Most camera lenses are also achromatic,

大部分相機鏡頭是「消色差」的，

meaning they focus both red and blue light to the same point.

意即相機會將紅光與藍光 聚焦在同一個點上。

Your eye is different.

你的眼睛則不同。

When red light from an object is in focus, the blue light is out of focus.

當一個物體的紅光是對焦的， 藍光就失焦了。

So why don't things look partially out of focus all the time?

那為什麼我們看東西 不會一直覺得有部分失焦？

To answer that question,

要回答這個問題，

we first need to look at how your eye and the camera capture light:

我們首先要來看 眼睛和相機如何捕捉光線：

photoreceptors.

光感受器。

The light-sensitive surface in a camera only has one kind of photoreceptor

相機中的感光表面只有一種光感受器，

that is evenly distributed throughout the focusing surface.

平均分布在整個對焦表面。

An array of red, green and blue filters on top of these photoreceptors

這些光感受器上有 一個陣列的紅、綠、藍濾鏡，

causes them to respond selectively to long, medium and short wavelength light.

讓它們分別對 長、中、短波光線產生反應。

Your eye's retinas, on the other hand, have several types of photoreceptors,

眼睛的視網膜則有 幾種不同的光感受器，

usually three for normal light conditions, and only one type for lowlight,

通常正常光線狀況下有三種， 低光源下只有一種，

which is why we're color blind in the dark.

這也是為什麼我們 在黑暗中會產生色盲。

In normal light, unlike the camera, we have no need for a color filter

在正常光線下， 我們不像相機需要色彩濾鏡，

because our photoreceptors already respond selectively

因為我們的光感受器 已經會對不同波長

to different wavelengths of light.

分別產生反應。

Also in contrast to a camera,

另外和相機不同之處在於

your photoreceptors are unevenly distributed,

你的光感受器並不平均分布，

with no receptors for dim light in the very center.

在最中間的地方， 沒有對昏暗光線的接收器。

This is why faint stars seem to disappear when you look directly at them.

這就是為什麼當我們直視 微弱的星光時，星星會消失不見。

The center also has very few receptors that can detect blue light,

中間位置也只有 極少數接收器可以偵測藍光，

which is why you don't notice the blurred blue image from earlier.

所以你之前就沒有注意到 模糊的藍色影像。

However, you still perceive blue there

不過你仍然可以察覺到那裡有藍色，

because your brain fills it in from context.

因為你的大腦會依據 周圍狀況將其補充進去。

Also, the edges of our retinas have relatively few receptors

而且視網膜邊緣 任何波長光線的接收器

for any wavelength light.

都比較少。

So our visual acuity and ability to see color

所以我們的視覺敏銳度 和察覺色彩的能力，

falls off rapidly from the center of our vision.

會從我們視線中心 急速往兩邊下降。

There is also an area in our eyes called the blind spot

眼睛裡也有個區域叫盲點，

where there are no photoreceptors of any kind.

那裡沒有任何種類的光感受器。

We don't notice a lack of vision there

我們不會察覺那裡看不到，

because once again, our brain fills in the gaps.

因為大腦再次幫我們填補了空隙。

In a very real sense, we see with our brains, not our eyes.

事實上，我們是用大腦來看事物， 而不是眼睛。

And because our brains, including the retinas,

而且因為我們的大腦，包括視網膜，

are so involved in the process,

在這個過程中涉入極深，

we are susceptible to visual illusions.

我們很容易產生視覺上的錯覺。

Here's another illusion caused by the eye itself.

這裡有另外一個錯覺的例子， 是眼睛本身造成的。

Does the center of this image look like it's jittering around?

這個畫面的中心看起來一直跳動嗎？

That's because your eye actually jiggles most of the time.

這是因為實際上 你的眼球一直在移動。

If it didn't, your vision would eventually shut down

如果不移動， 你的視覺最終將會停止，

because the nerves on the retina stop responding to a stationary image

因為視網膜上的神經 對強度不變的靜止畫面

of constant intensity.

停止產生反應。

And unlike a camera,

和相機不同，

you briefly stop seeing whenever you make a larger movement with your eyes.

當你的眼睛大幅移動時， 視力會短暫停止。

That's why you can't see your own eyes shift

這就是為什麼你在鏡子中，

as you look from one to the other in a mirror.

看不到自己的眼睛 從一處移動到另一處。

Video cameras can capture details our eyes miss,

攝影機可以捕捉 我們眼睛錯過的細節，

magnify distant objects

放大遠處的物體

and accurately record what they see.

並正確記錄看到的東西。

But our eyes are remarkably efficient adaptations,

但是我們的眼睛是幾億年來

the result of hundreds of millions of years

與大腦共演化之後

of coevolution with our brains.

高效進化的產物。

And so what if we don't always see the world exactly as it is.

就算我們不會每次都看到 世界確切的樣子又如何。

There's a certain joy to be found watching stationary leaves

你可以找到某些樂趣， 看著靜止的樹葉

waving on an illusive breeze,

在錯覺中隨風搖曳。

and maybe even an evolutionary advantage.

甚至觀察到演化的優勢。

But that's a lesson for another day.

這堂課改天再說吧。