Here's a grid, nothing special, just a basic grid, very grid-y.

這有一張網格圖，沒什麼特別就是普通的格子。

But look closer, into this white spot at the center where the two central vertical and horizontal lines intersect.

但仔細看中心的白點，就是兩條平行和垂直線相交的點。

Look very closely. Notice anything funny about this spot?

再靠近一點看，這個點有比較特別嗎？

Yeah, nothing.

呃...沒有。

But keep looking. Get weird and stare at it.

但繼續盯著它，開始有點怪怪的。

Now, keeping your gaze fixed on this white spot, check what's happening in your peripheral vision.

現在請把目光定在這個點上，用餘光看看附近的點。

The other spots, are they still white? Or do they show weird flashes of grey?

其他的點還是白的嗎？還是閃著詭異的灰色？

Now look at this pan for baking muffins.

再看這個烤瑪芬的烤盤。

Oh, sorry, one of the cups is inverted. It pops up instead of dipping down.

喔有其中一個好像反了，應該要凹下去結果它凸起來。

Wait, no spin the pan. The other five are domed now?

但把它轉過來看，其他五個才是反的吧？

Whichever it is, this pan's defective.

反正就是這個烤盤有問題。

Here's a photo of Abraham Lincoln, and here's one upside down.

這裡有林肯的照片還有另一張是反著放的。

Nothing weird going on here.

應該沒什麼奇怪的吧！

Wait, turn that upside down one right side up... what have they done to Abe?

但把反的照片擺正後...他們對林肯幹了什麼好事？

Those are just three optical illusions, images that seem to trick us.

上述只是三個「錯視」的例子，我們會被所見欺騙。

How do they work?

這是怎麼回事？

Are magical things happening in the images themselves?

這幾張圖有什麼古怪嗎？

While we could certainly be sneaking flashes of grey into the peripheral white spots of our animated grid,

我們是可以把影片裡的白點附近，偷偷混進灰點。

first off, we promise we aren't.

但我們先澄清絕對沒有。

You'll see the same effect with a grid printed on a plain old piece of paper.

你自己用紙印一樣的圖，出來也會看到一樣的效果。

In reality, this grid really is just a grid.

事實上它只是普通的網格。

But not to your brain's visual system.

但大腦的視覺系統可不這麼認為。

Here's how it interprets the light information you call this grid.

他們是這麼解讀網格上的光學訊息：

The white intersections are surrounded by relatively more white on all four sides than any white point along a line segment.

交叉上的白點被相對較白的四條線包圍，其他的交叉點也是如此。

Your retinal ganglion cells notice that there is more white around the intersections because they are organized to increase contrast with lateral inhibition.

視網膜神經節細胞發現交叉點附近有更白的部分，因為神經的「側抑制」會增加對比。

Better contrast means it's easier to see the edge of something.

增加對比意味著能更清楚發現界線。

And things are what your eyes and brain have evolved to see.

眼睛和腦的進化就是為了看見這些差異。

Your retinal ganglion cells don't respond as much at the crossings because there is more lateral inhibition for more white spots nearby compared to the lines, which are surrounded by black.

視網膜神經節細胞不把焦點放在交叉點上，因為會受到周圍白點更多的「側抑制」影響，因為會受到周圍白點更多的「側抑制」影響。

This isn't just a defect in your eyes;

這也不能說是眼睛的問題。

if you can see, then optical illusions can trick you with your glasses on or with this paper or computer screen right up in your face.

因為就算你戴著眼鏡、 用紙本或電腦螢幕看圖都有這樣的錯視效果。

What optical illusions show us is the way your photo receptors and brain assemble visual information into the three-dimensional world you see around you, where edges should get extra attention because things with edges can help you or kill you.

錯視讓我們發現，我們的感光受器和大腦如何把生活周遭的光學訊息整合在一起，通常這些邊緣或界線需要格外留意，因為他們不是會幫助你就是會害死你。

Look at that muffin pan again. You know what causes confusion here?

再重新看看瑪芬烤盤，知道哪裡怪怪的了嗎？

Your brain's visual cortex operates on assumptions about the lighting of this image.

大腦的視覺皮層會自己假想一個光源。

It expects light to come from a single source, shining down from above.

它假設光是單一方向，從圖的上方往下照。

And so these shading patterns could only have been caused by light shining down on the sloping sides of a dome, or the bottom of a hole.

所以陰影會在突起的下方或是凹陷的上方。

If we carefully recreate these clues by drawing shading patterns, even on a flat piece of paper, our brain reflexively creates the 3D concave or convex shape.

只要我們畫好陰影的位置，就算是在平面上，我們的腦會自然地製造出凸起或凹陷的錯覺。

Now for that creepy Lincoln upside down face.

至於詭異的林肯顛倒照片。

Faces trigger activity in areas of the brain that have specifically evolved to help us recognize faces.

「臉」的影像會啟動大腦中特殊進化來辨識臉部的區域。

Like the fusiform face area and others in the occipital and temporal lobes.

例如梭狀臉區 (FFA) 或枕葉和顳葉的某些區域。

It makes sense, too, we're very social animals with highly complex ways of interacting with each other.

這也很合理，因為我們是具有高度複雜化的互動模式的社會性動物。

When we see faces, we have to recognize they are faces and figure out what they're expressing very quickly.

當我們看到臉，必須要認出「那是臉」然後趕快理解他們的表情在說什麼。

And what we focus on most are the eyes and mouth.

我們最容易注意到的大部分為眼睛和嘴巴。

That's how we figure out if someone is mad at us or wants to be our friend.

這是我們如何察覺別人是在對我們生氣還是想跟我們當朋友。

In the upside down Lincoln face, the eyes and mouth were actually right side up, so you didn't notice anything was off.

在反過來的林肯的臉上，眼睛和嘴巴其實是被擺正的，所以你不會覺得有什麼問題。

But when we flipped the whole image over, the most important parts of the face, the eyes and mouth, were now upside down, and you realized something fishy was up.

但當我們把照片轉正，臉上最重要的部份，也就是眼睛和嘴巴反過來了，你就會發現哪裡有問題。

You realized your brain had taken a short cut and missed something.

你發現你的腦抄捷徑結果漏掉一些細節。

But your brain wasn't really being lazy, it's just very busy.

但你的腦不是想偷懶，而是因為他太忙了。

So it spends cognitive energy as efficiently as possible, using assumptions about visual information to create a tailored, edited vision of the world.

所以要儘可能有效率地耗費能量，運用理所當然的假設來理解、創造出完美的世界。

Imagine your brain calling out these edits on the fly:

想像你的腦有以下的飛快對話：

"Okay, those squares could be objects.

「嗯這些方格可能蠻重要的。」

Let's enhance that black-white contrast on the sides with lateral inhibition.

「那我們用『側抑制』加強黑白的對比。」

Darken those corners!

「把其他角落變黑！」

Dark grey fading into light grey?

「深灰漸淡成淺灰？」

Assume overhead sunlight falling on a sloping curve. Next!

「假裝光從上面來製造出陰影， 下一個！」

Those eyes look like most eyes I've seen before, nothing weird going on here."

「這些眼睛跟平常一樣沒什麼問題。」

See? Our visual tricks have revealed your brain's job as a busy director of 3D animation in a studio inside your skull, allocating cognitive energy and constructing a world on the fly with tried and mostly -- but not always -- true tricks of its own.

看到了嗎？ 這些錯視的把戲揭露大腦在你頭殼下的工作室，像 3D 動畫導演的忙碌工作要有效的分配精力，迅速地建構出周遭的世界，可惜有時候會出錯。