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  • 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

Watch the center of this disk.

請看轉盤的中心

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B1 中級 中文 美國腔 TED-Ed 眼睛 感受器 光線 相機 視網膜

【TED-Ed】眼睛 VS.相機 (Eye vs. camera - Michael Mauser)

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    稲葉白兎 發佈於 2015 年 05 月 03 日
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