What are those colors you see when you rub your eyes? - Paul CJ Taylor

翻译人员: Hagar Abdelrahman 校对人员: suya f.

In the late 1600s, Isaac Newton conducted a series of experiments

17 世纪末，艾萨克·牛顿 进行了一系列的实验，

that broke the two most fundamental rules of eye safety—

这些实验打破了眼睛 安全的两个最基本的规则，

in one, he stared at the sun,

一个是他盯着太阳，

and in the other he stuck a needle under his eyeball.

另一个是他在眼球下扎了一根针。

Newton was hoping to better understand the lights and colors

牛顿希望能更好地理解闭上眼睛时

that sometimes appear when your eyes are closed.

有时侯会出现的光线和颜色。

If you've ever sat around an evening campfire or, unlike Newton,

如果你曾经围坐在篝火旁， 或者，不像牛顿

unintentionally glanced at the sun,

无意中看了一眼太阳，

you may have noticed illuminated patterns briefly dance along your vision

那么你可能会注意到发光的图案 在消失在黑暗中之前

before fading into darkness.

会沿着你的视觉短暂地跳舞。

So how do these visual illusions, known as afterimages, form?

那么，这些被称为后像的 视觉错觉是如何形成的？

Inside the retina, specialized cells called photoreceptors

在视网膜内部， 称为感光受器的特殊细胞

take in light and turn it into a signal the brain can understand.

吸收光并将它变成 大脑可以理解的信号。

Photoreceptors contain thousands of molecules called photopigments,

感光受器包含着数千个 称为光色素的分子，

which are sensitive to particular colors.

它们对一些颜色敏感。

When a light-photon strikes a pigment, part of the photopigment’s structure,

当一个光质子撞击色素时， 光色素结构的一部分，

known as chromophore,

叫发色团通过暂时改变 其分子结构来吸收能量，

absorbs the energy by temporarily altering its molecular structure

in a process called bleaching.

这个过程叫漂白。

This reconfiguration induces a cascade of chemical reactions

这种重构会引发一系列化学反应

that route an electrical pulse to the brain.

将电脉冲传递到大脑。

And once your brain assembles the signals

一旦你的大脑汇集了

from approximately 200 million photoreceptor cells,

来自大约 2 亿个 感光受器细胞的信号，

you see an image.

你就会看到一张图像。

So how does this lead to an afterimage?

那么这如何导致后像呢？

Scientists aren't quite sure,

科学家们还不太确定，

but a leading theory suggests that photoreceptors may be to blame.

但一个领先的理论表明， 原因可以是感光受器。

Looking at something bright causes many pigments in a photoreceptor to bleach.

看着明亮的东西会导致 感光受器中的许多色素漂白。

In this state, photopigments can't absorb light well and need to regenerate.

在这种状态下，光色素无法 很好地吸收光线，光色素需要再生。

However, it's believed that photoreceptor cells momentarily continue to fire

不过，人们认为， 感光受器细胞会暂时继续

and to send signals to the brain,

向大脑发送信号， 当你闭上眼睛时，

熊熊燃烧的篝火 会变成为明亮的图案。

transforming the blazing campfire to a bright pattern as you close your eyes.

This is known as a positive afterimage.

这被称为正后像。

Positive afterimages normally fade within a few seconds,

正后像通常会在几秒钟内消失，

and, under certain conditions,

在某些条件下，

can be replaced by what is known as a negative afterimage.

也可以被所谓的负面后像所取代。

The original colors appear to be swapped for their approximate complement:

原始颜色似乎被替换为其近似的补色：

blue with yellow, red with cyan, green with magenta.

蓝色与黄色，红色与青色， 绿色与洋红色。

If you fixate on a bright image of a green flower on a yellow background,

如果你专注于黄色背景上的一朵 绿色花朵的明亮图像，

then glance at a white screen, or close your eyes,

然后看一眼白色的屏幕， 或者闭上眼睛，

you will see a negative afterimage of a magenta flower on a blue background.

你将看到蓝色背景上的 一朵洋红色花朵的负面后像。

Scientists are still working to understand the origins of negative afterimages,

科学家们仍在努力了解负面后像的起源，

and there are multiple theories.

有几个理论。

Some evidence suggests the source lies in the layers of neuronal cells

一些证据表明，其来源是视网膜中 神经元细胞层内的

in the retina called ganglion cells,

神经节细胞，

while other research implicates deeper processing in the brain.

而其他研究则涉及大脑 进行更深层次的处理。

Another theory suggests the source lies, again, in the photoreceptors.

另一个理论表明， 来源再次在于感光受器。

The idea is that certain cells are activated if one color—

这个想法是，如果看到一种颜色

such as green— is viewed.

例如绿色，某些细胞就会被激活。

Meanwhile, other cells that are normally activated by viewing red—

同时，通常通过看绿色的补色红色，

green’s complement— are then left deactivated.

而激活的其他细胞则处于停用状态。

But if you stare at a green image for an extended period of time,

但是，如果你长时间盯着绿色图像，

it's thought that while the activated green cells become fatigued,

人们会认为，激活的绿细胞 变得疲劳的同时，

the red cells are still sensitive to input.

红细胞仍然对输入敏感。

As a result, when you look away or close your eyes,

结果，当你移开视线或闭上眼睛时，

the opposing red cells are momentarily more active than the tired green cells,

对立的红色细胞会暂时 比疲惫的绿色细胞更活跃，

creating the perception of a color that is close to the original color’s complement.

从而产生一种接近原始颜色 补色的色彩感知。

But scientists still don’t know for sure.

但是科学家们还不确定。

And yet another puzzling visual illusion involves no light or staring at all.

还有另一种令人费解的视觉错觉， 根本没有光线或盯着。

Simply rubbing, or like Newton, inadvisably stabbing behind your eye

简单地摩擦，或者像牛顿一样， 不明智地在眼后刺伤

can generate the brief appearance of lights and colors.

会产生光线和色彩的短暂出现。

These are known as pressure phosphenes.

这些被称为压力光幻视。

Newton hypothesized that the colorful circles of light

牛顿假设彩色光圈是

were caused by the physical bending of his retina.

由物理弯曲视网膜造成的。

Today, some scientists believe that pressure phosphenes

现在，一些科学家认为，压力光幻视

are indeed the result of distortion—

的确是扭曲的结果—

that rubbing or poking your eyes physically stretches neurons,

就是摩擦或扎眼睛 会在物理上伸展神经元，

bending the photoreceptors out of shape and causing them to fire.

使感光受器弯曲变形 并导致它们发射。

But again, the science of phosphenes is far from settled,

但是，同样，光幻视 的科学还远远未确定，

and there are other ways they can form.

它们还有其他形成方式。

For example, during procedures where magnetic pulses are sent

例如，在将磁脉冲发送

into specific parts of the brain,

到大脑具体部分的过程中，

some people, including those with certain types of blindness,

一些人，包括患某些类型失明的人

report seeing flashes of light.

都报告说看到了闪光。

And astronauts, traveling where few others have gone before,

宇航员在以前很少 有人去过的地方旅行，

often describe seeing similar effects when exposed to cosmic radiation

他们经常描述在暴露于来自

from the Sun and other stars.

太阳和其他恒星的宇宙辐射 时会遇到类似的效果。