英語(yǔ)聽(tīng)力文摘 眼睛的“盲區(qū)”

人們都說(shuō)“眼睛是心靈的窗戶”——通過(guò)雙眼,我們能看世間百態(tài),能看人情冷暖,能看繽紛色彩……

可大多數(shù)人并不知道,在視網(wǎng)膜的某一個(gè)地方,世界是黑白的,是沒(méi)有色彩的.

今天,讓我們一起來(lái)學(xué)習(xí)有關(guān)視網(wǎng)膜的知識(shí).了解眼睛的“盲區(qū)”……

The Green Door

Don: Here’s a simple demonstration you can do with cool implications. Find a large object that is brightly colored–let’s make it a green door.

Stand with that door to your side but don’t look directly at it; you want it to be in your peripheral vision. Now, without shifting your gaze, examine the door in the edge of your field of vision. What color is it? Answer? It’s still green.

Yael: It’s still green? What kind of experiment is that? I thought you are going to say something happens to the color.

D: That's exact right! The color stays green, which means something has happened – because nothing in your peripheral vision should have any color at all.

Y: Nothing in your peripheral vision should have any color? Why not?

D: Because color is what we perceive when light of a particular frequency meets cones–special cells in your retina. But the light being reflected off the door is only landing on the outside edge of your retina. And there are almost no cones on the edges. Everything we see roughly seventy-five degrees away from the point we’re fixed on should be black and white.

Y: That's fascinating! But why is the door still green?

D: Presumably the door remains green because vision isn’t a simple matter of retinal cells. All the data your eyes send is interpreted by the brain. Your brain knows that the door is green, so it supplies information that isn’t really there to keep the image stable.

This is just one of the many ways your brain saves time and energy by making reasonably safe assumptions about the world around you.

D: 告訴你一個(gè)很簡(jiǎn)單的論證：通過(guò)它你可以得出很酷的答案。找到一個(gè)大的顏色鮮艷的物件——將其視作一扇綠色的門。

靠著那扇門站定，但是不要直視它，只是把它納入你的周邊視野即可?，F(xiàn)在，不改變凝視的方向，從你視野的最邊緣仔細(xì)看看那扇門。它是什么顏色的?答案是什么?那扇門依然是綠色的。

Y: 還是綠色?這是個(gè)什么實(shí)驗(yàn)啊?我猜你接下來(lái)應(yīng)該會(huì)講講，那扇門的顏色究竟發(fā)生了什么神奇的事情。

D: 當(dāng)然!門保持綠色就意味著發(fā)生了什么改變——因?yàn)樵谥苓呉曇胺秶鷥?nèi)事沒(méi)有什么顏色的。

Y: 周邊視野范圍內(nèi)是沒(méi)有顏色?為什么?

D: 因?yàn)?，?dāng)特定波長(zhǎng)的光線作用于視錐細(xì)胞(視網(wǎng)膜中的一種特殊的細(xì)胞)時(shí)我們所接收到的便是顏色。但是，從門上發(fā)射出來(lái)的光線僅能到達(dá)視網(wǎng)膜的外緣，在視網(wǎng)膜的外緣幾乎沒(méi)有視錐細(xì)胞。從我們所凝視的方向斜75度角所看到的所有東西都只能是黑白的。

Y: 太神奇了!可為什么門還是綠色的呢?

D: 門一直保持綠色大概是因?yàn)槲覀兊囊曈X(jué)并不僅僅是視網(wǎng)膜細(xì)胞所能控制的吧。由眼睛傳送的所有信息都是經(jīng)過(guò)大腦編譯的。大腦所給出的信息是：門是綠色的。因而，大腦傳送出了并未遵循圖像的信息。

為節(jié)省時(shí)間與精力，大腦對(duì)你周圍的世界作出合理、安全的假設(shè)——而這僅僅是眾多省時(shí)省力的方法之一。