Scott Fraser: The problem with eyewitness testimony

Translator: Joseph Geni Reviewer: Morton Bast

翻译人员: Wei Wu 校对人员: Jing Peng

The murder happened a little over 21 years ago,

这是一宗21年前发生的谋杀案。

January the 18th, 1991,

1991年1月18日，

in a small

在加利福尼亚州

bedroom community

林伍德（Lynwood）的一个

of Lynwood, California, just a few miles

贫困社区内发生的。这个社区位于

southeast of Los Angeles.

洛杉矶东南，相距几英里。

A father came out of his house

一位父亲从屋子里走出

to tell his teenage son and his five friends

告诉他的儿子和他儿子的五个朋友，

that it was time for them to stop horsing around

不要在房前的草坪和走道上

on the front lawn and on the sidewalk,

打闹了。

to get home, finish their schoolwork,

该回家写作业，

and prepare themselves for bed.

准备睡觉了。

And as the father was administering these instructions,

当父亲在说着这些的时候，

a car drove by, slowly,

一辆车缓缓驶过。

and just after it passed the father and the teenagers,

当车刚驶过这位父亲和孩子们的时候，

a hand went out from the front passenger window,

一只手从车前窗伸了出来

and -- "Bam, Bam!" -- killing the father.

然后“砰砰”两声，父亲被杀了，

And the car sped off.

车扬长而去。

The police,

警察属

investigating officers, were amazingly efficient.

调查此案的工作人员相当有效率。

They considered all the usual culprits,

他们考虑了所有可能的罪犯，

and in less than 24 hours, they had selected their suspect:

24小时内，他们确立了可疑对象：

Francisco Carrillo, a 17-year-old kid

一个17岁的孩子，名叫 Francisco Carrillo.

who lived about two or three blocks away

他住在离枪击案发地

from where the shooting occurred.

两三个街区的地方。

They found photos of him. They prepared a photo array,

他们找到他的照片，并准备了一组照片（供目击者识别）。

and the day after the shooting,

枪击发生第二天，

they showed it to one of the teenagers, and he said,

警察让一个目击者指认照片，那个孩子说：

"That's the picture.

"就是他，

That's the shooter I saw that killed the father."

他就是那个杀人凶手。"

That was all a preliminary hearing judge had

预审听证法官听到了这样的证词

to listen to, to bind Mr. Carrillo over to stand trial

同意以一级谋杀罪名起诉 Carrillo

for a first-degree murder.

并移交正式审判。

In the investigation that followed before the actual trial,

在正式审判开始前有个调查，

each of the other five teenagers was shown

另外五名目击证人全部进行了指认

photographs, the same photo array.

使用与上次相同的一组照片。

The picture that we best can determine was probably

在以上头像照中，我们认为

the one that they were shown in the photo array

左下角的那张图片最有可能是

is in your bottom left hand corner of these mug shots.

出现在指认照片中的那张。

The reason we're not sure absolutely is because

由于司法系统证据保存机制存在的问题

of the nature of evidence preservation

使得我们对于这些照片当时的情况

in our judicial system,

并不是百分百确定。

but that's another whole TEDx talk for later. (Laughter)

但这是另外一个 TEDx 演讲的内容了（笑声）

So at the actual trial,

在正式审判中

all six of the teenagers testified,

六个少年都做了证，

and indicated the identifications they had made

并指出他们在照片指认中指认出来的

in the photo array.

是同一个人。

He was convicted. He was sentenced to life imprisonment,

他被判罪名成立，终身监禁

and transported to Folsom Prison.

被运押至佛森监狱

So what's wrong?

那么，哪里错了？

Straightforward, fair trial, full investigation.

情节简单，审判公正，调查完整。

Oh yes, no gun was ever found.

哦对，没有找到枪！

No vehicle was ever identified as being the one

而且也没有找到凶手

in which the shooter had extended his arm,

当时使用的汽车，

and no person was ever charged with being the driver

也没有找到当时为凶手

of the shooter's vehicle.

开车的人。

And Mr. Carrillo's alibi?

那么 Carrillo 的不在场证词呢？

Which of those parents here in the room might not lie

在座的各位中有谁能够保证

concerning the whereabouts of your son or daughter

会在子女受到谋杀调查的时候

in an investigation of a killing?

坚持不撒谎呢？

Sent to prison,

他被投入监狱，

adamantly insisting on his innocence,

但他坚持自己是清白的，

which he has consistently for 21 years.

21年来，他一直如此表示。

So what's the problem?

哪里出了问题？

The problems, actually, for this kind of case

实际上，这类官司中存在的问题

come manyfold from decades of scientific research

都涉及人类记忆机制，学术界在这个问题上

involving human memory.

研究了很多年。

First of all, we have all the statistical analyses

首先，我们通过“洗冤计划”（Innocence Project）

from the Innocence Project work,

提供的统计数字可以看到

where we know that we have, what,

从中我们知道

250, 280 documented cases now where people have

有至少280宗案件

been wrongfully convicted and subsequently exonerated,

被告被误判,从而最终得以无罪释放，

some from death row, on the basis of later DNA analysis,

有些被告被判死刑，最终靠DNA比对洗冤，

and you know that over three quarters of all of those cases

在这些嫌疑人最终被无罪释放的案件中

of exoneration involved only eyewitness identification

有超过3/4的案件是仅仅依靠目击证人证词

testimony during the trial that convicted them.

将嫌疑人定罪的。

We know that eyewitness identifications are fallible.

目击证人的证词不是绝对准确的。

The other comes from an interesting aspect

这也引出人类记忆中有趣的一面

of human memory that's related to various brain functions

牵涉到大脑很多不同的功能模块

but I can sum up for the sake of brevity here

不过我可以在这里简单的

in a simple line:

概括一下：

The brain abhors a vacuum.

"大脑痛恨空白", （会自动填充信息）

Under the best of observation conditions,

在最好的观察条件下，

the absolute best,

绝对最好的,

we only detect, encode and store in our brains

我们也只能感知到所处环境中极少的信息

bits and pieces of the entire experience in front of us,

并将其编码，存储在大脑中，

and they're stored in different parts of the brain.

保存在大脑的不同部位。

So now, when it's important for us to be able to recall

那么当我们需要回忆起

what it was that we experienced,

我们所经历的事情时，

we have an incomplete, we have a partial store,

我们大脑中的记忆是不完整的,

and what happens?

大脑会怎么做？

Below awareness, with no requirement for any kind of

不需要你的意识进行任何形式的干预，

motivated processing, the brain fills in information

大脑会自动的进行信息填充,

that was not there,

这些信息并不真实,

not originally stored,

或并不是＂原始储备＂

from inference, from speculation,

而是通过推断、猜测而得,

from sources of information that came to you,

填充上任何无意识的信息,

as the observer, after the observation.

作为事发之后的目击者.

But it happens without awareness such that

这一切都是悄然进行的，

you don't, aren't even cognizant of it occurring.

你觉察不到这一切的发生。

It's called reconstructed memories.

这被称作记忆重构。

It happens to us in all the aspects of our life, all the time.

大脑无时无刻不在进行着记忆的重构。

It was those two considerations, among others --

众多疑点中有两点——

reconstructed memory, the fact about the eyewitness fallibility --

重构记忆，目击证人证词的不可靠性——

that was part of the instigation

这些疑点鼓舞了

for a group of appeal attorneys

一些上诉律师

led by an amazing lawyer named Ellen Eggers

在充满个人魅力的律师

to pool their experience and their talents together

Ellen Eggers 的带领下通力合作

and petition a superior court

向上级法院提交了

for a retrial for Francisco Carrillo.

要求重审 Francisco Carrillo 案的请愿书。

They retained me, as a forensic neurophysiologist,

我也以神经生理学取证专家的身份参与其中。

because I had expertise

因为我是目击证人

in eyewitness memory identification,

记忆分析领域的专家。

which obviously makes sense for this case, right?

这在本案中很重要，不是么？

But also because I have expertise and testify about

另外我还有人类夜视能力分析的经验

the nature of human night vision.

并为法庭提供过专家证词。

Well, what's that got to do with this?

这跟本案有什么关系？

Well, when you read through the case materials

当你翻阅了 Carrillo 案件中的

in this Carrillo case,

原始笔录，

one of the things that suddenly strikes you is that

你会突然发现在调查报告中

the investigating officers said the lighting was good

调查人员声称枪击案发生时

at the crime scene, at the shooting.

现场的光线很好。

All the teenagers testified during the trial

所有的目击者作证时都说

that they could see very well.

现场的光线足以看清（嫌犯）。

But this occurred in mid-January,

但是枪击发生的地点在北半球，

in the Northern Hemisphere, at 7 p.m. at night.

时间是1月中旬的晚上7点。

So when I did the calculations

然后，我计算了一下

for the lunar data and the solar data

枪击案发生的地点在当天晚上7点的

at that location on Earth at the time of the incident

太阳和月亮的位置，

of the shooting, all right,

然后我注意到，

it was well past the end of civil twilight

那时太阳已经完全落下

and there was no moon up that night.

而月亮那天也没有升起。（朔月）

So all the light in this area from the sun and the moon

当时日月能够提供的亮度

is what you see on the screen right here.

跟现在这块屏幕的亮度差不多。

The only lighting in that area had to come

所以当时，人工光源是唯一的

from artificial sources,

光照来源。

and that's where I go out and I do the actual reconstruction

于是接下来我利用光度计

of the scene with photometers, with various measures

重建了当时的场景，考虑了

of illumination and various other measures of

不同的光亮程度和不同的颜色成分

color perception, along with special cameras

并且使用特殊的摄像机

and high-speed film, right?

进行了高速摄像，

Take all the measurements and record them, right?

将这些实验数据和实际场景的效果都记录了下来，

And then take photographs, and this is what the scene

然后我们拍摄了一些照片，

looked like at the time of the shooting

这张就是类似枪击事件发生时候的照片，

from the position of the teenagers

从当年少年们所站的位置,

looking at the car going by and shooting.

目击汽车驶过,然后嫌疑人开枪行凶。

This is looking directly across the street

这张展示的是从他们站的地方

from where they were standing.

径直看过街道的照片。

Remember, the investigating officers' report said

注意，调查专员的报告中

the lighting was good.

提到光线很好。

The teenagers said they could see very well.

孩子们说他们看得很清楚。

This is looking down to the east,

这张是顺着道路向东看的照片，

where the shooting vehicle sped off,

罪犯们就是驾车从此逃逸的。

and this is the lighting directly behind the father

这张照片展示的是父亲和孩子们

and the teenagers.

所站位置背后的光照强度。

As you can see, it is at best poor.

我们可以看到，非常的暗。

No one's going to call this well-lit, good lighting,

没人会把这样的光照说成是光照充足的，

and in fact, as nice as these pictures are,

事实上，这些照片很逼真，

and the reason we take them is I knew I was going to have to testify in court,

我们拍摄这些照片，是为了作为证据呈上法庭，

and a picture is worth more than a thousand words

因为一图胜千言，

when you're trying to communicate numbers,

尤其是你要解释很多抽象概念

abstract concepts like lux, the international measurement

例如勒克斯（lux），国际通用的照明单位

of illumination, the Ishihara color perception test values.

或是石原色觉测试值（Ishihara color perception test values）之类的概念时。

When you present those to people who are not well-versed

当你跟那些非专业人士（陪审团成员）

in those aspects of science and that, they become

讨论这些抽象概念的时候

salamanders in the noonday sun. It's like

他们就会开始打瞌睡，走神溜号。

talking about the tangent of the visual angle, all right?

比如讨论视角的切线概念时，

Their eyes just glaze over, all right?

他们的眼皮子便开始打架

A good forensic expert also has to be a good educator,

一个好的鉴定专家，首选得是一个好老师

a good communicator, and that's part of the reason

善于交流沟通。也是我们拍摄

why we take the pictures, to show not only

这些照片的目的。这样我们不仅可以

where the light sources are, and what we call the spill,

展示光源的位置，光源的照射角度，

the distribution, but also so that it's easier

光照的分布，还可以让证据鉴定人（即法官）

for the trier of fact to understand the circumstances.

让法官直观理解现场的环境。

So these are some of the pictures that, in fact,

这些就是我在法庭作证时

I used when I testified,

用到的部分照片，

but more importantly were, to me as a scientist,

但是作为一名科学家，更为重要的是

are those readings, the photometer readings,

我能够根据这些数据，光度计的数据，

which I can then convert into actual predictions

推断出来在这样的光照环境下，

of the visual capability of the human eye

以人类的视物能力

under those circumstances,

能够看得多清楚，

and from my readings that I recorded at the scene

再加上我事先测量的同样的时间点

under the same solar and lunar conditions

同样的日光和月光照射条件下的

at the same time, so on and so forth, right,

光照数据，综合累加起来，

I could predict

我能断定

that there would be no reliable color perception,

当时的光照不足以分辨不同的颜色（视网膜锥状细胞负责感知颜色）

which is crucial for face recognition,

也就不能准确的辨别人脸，

and that there would be only scotopic vision,

而当只有暗视觉的时候（视网膜杆状细胞负责感知明暗）

which means there would be very little resolution,

能看到的清晰度就大打折扣

what we call boundary or edge detection,

这个时候只能够看清物体的轮廓，

and that furthermore, because the eyes would have been

因为在这样的光照条件下，

totally dilated under this light, the depth of field,

眼睛会完全失去焦点，无法对焦，

the distance at which you can focus and see details,

这个时候你能看到的范围

would have been less than 18 inches away.

不会超过18英寸。

I testified to that to the court,

我在法庭上做了如上表述，

and while the judge was very attentive,

尽管法官已经听得非常仔细，

it had been a very, very long hearing

重审请愿的听证工作

for this petition for a retrial, and as a result,

还是持续了很长时间，直到最后

I noticed out of the corner of my eye

我终于意识到

that I thought that maybe the judge was going to need

我们可能需要一些

a little more of a nudge

比数字更直观的东西

than just more numbers.

来说服法官。

And here I became a bit audacious,

这时我变得有点大胆

and I turned

我反过来

and I asked the judge,

向这个法官挑战，

I said, "Your Honor, I think you should go out

我说，“法官大人，我想最好还是

and look at the scene yourself."

您亲自去现场看看。“

Now I may have used a tone which was more like a dare

这个时候我的口气更像是命令

than a request — (Laughter) —

而不是请求——（笑声）

but nonetheless, it's to this man's credit and his courage

尽管如此，这位富有勇气和声望的法官

that he said, "Yes, I will."

回答说，“好，我亲自看。”

A shocker in American jurisprudence.

这在整个美国司法审判过程中都很罕见。

So in fact, we found the same identical conditions,

最后，我们在相同的天气条件下

we reconstructed the entire thing again,

再次构造出整个案发环境，

he came out with an entire brigade of sheriff's officers

而法官大人在一大群地方警察的保护下

to protect him in this community, all right? (Laughter)

来到了这个社区。（笑声）

We had him stand actually slightly in the street,

我们让他站在更靠近街道的位置，

so closer to the suspect vehicle, the shooter vehicle,

距离嫌疑车辆，枪手乘坐的汽车

than the actual teenagers were,

比那些少年更近一些，

so he stood a few feet from the curb

他站在距离街道只有几英尺的地方

toward the middle of the street.

朝着街道正中央望去。

We had a car that came by,

我们让一辆车开了过去，

same identical car as described by the teenagers, right?

跟少年们描述的一模一样的车，

It had a driver and a passenger,

里面坐了一个司机一个乘客，

and after the car had passed the judge by,

当汽车经过法官身旁的时候，

the passenger extended his hand,

乘客从车里伸出自己的手，

pointed it back to the judge as the car continued on,

在移动的汽车里将手指向法官，

just as the teenagers had described it, right?

跟少年们说的一模一样，

Now, he didn't use a real gun in his hand,

当然他手里拿着的不是真的手枪，

so he had a black object in his hand that was similar

而是一个跟目击者描述的手枪相似的

to the gun that was described.

一个黑色的替代物。

He pointed by, and this is what the judge saw.

他指着法官，这张照片是法官看到的情形

This is the car 30 feet away from the judge.

法官距离汽车三十英尺远，

There's an arm sticking out of the passenger side

从副驾驶座这边伸出一只手

and pointed back at you.

指着你。

That's 30 feet away.

距离30英尺，

Some of the teenagers said that in fact the car

几个少年声称枪响的时候他们距离汽车

was 15 feet away when it shot.

只有15英尺这么远。

Okay. There's 15 feet.

好，这是15英尺。

At this point, I became a little concerned.

这时我开始有点担心了。

This judge is someone you'd never want to play poker with.

这个法官是那种完全不苟言笑的人。

He was totally stoic. I couldn't see a twitch of his eyebrow.

他面无表情，连眉毛都没动一下。

I couldn't see the slightest bend of his head.

我觉得这些没能改变一点点他的看法。

I had no sense of how he was reacting to this,

我不知道他会有什么反应，

and after he looked at this reenactment,

在他看完这些现场模拟之后，

he turned to me and he says,

他转向我，问道，

"Is there anything else you want me to look at?"

“你还有什么想展示给我看的么？”

I said, "Your honor," and I don't know whether I was

我说，“法官大人，” 此时我也不清楚

emboldened by the scientific measurements that I had

是我口袋中的科学测量数据

in my pocket and my knowledge that they are accurate,

和我掌握的准确知识给了我勇气，

or whether it was just sheer stupidity,

还是我当时昏了头——

which is what the defense lawyers thought — (Laughter) —

辩护律师倒是这么看我的——（笑声）

when they heard me say,

他们听见我说的是，

"Yes, Your Honor, I want you stand right there

“有的，法官大人，我希望你站在原地

and I want the car to go around the block again

我想叫车子开一圈绕回来

and I want it to come and I want it to stop

我想让车子停在您的正前方

right in front of you, three to four feet away,

距离你只有三英尺远，

and I want the passenger to extend his hand

然后让里面的乘客把手伸出来

with a black object and point it right at you,

拿着黑色的“手枪”指着你，

and you can look at it as long as you want."

你想看多久就看多久。”

And that's what he saw. (Laughter)

这就是他看到的。（笑声）

You'll notice, which was also in my test report,

你可能注意到了，我在报告中也写了，

all the dominant lighting is coming from the north side,

主要光源都是从北面射过来，

which means that the shooter's face would

这意味着枪手的脸是看不清的。

have been photo-occluded. It would have been backlit.

枪手的脸是背光的。

Furthermore, the roof of the car

另外，汽车的顶棚

is causing what we call a shadow cloud inside the car

在汽车内造成了阴影的效果，

which is making it darker.

使得车内更加昏暗。

And this is three to four feet away.

这只有三到四英尺的距离。

Why did I take the risk?

我为什么要冒这个险？

I knew that the depth of field was 18 inches or less.

因为我知道人的眼睛只能看到18英寸远。

Three to four feet, it might as well have been

三到四英尺，跟一个足球场的距离

a football field away.

一样远。

This is what he saw.

这是他能看到的。

He went back, there was a few more days of evidence

他回去后，又经过了几天的听证工作。

that was heard. At the end of it,

听证结束后，

he made the judgment that he was going to grant

他作出裁决，批准了请愿书的

the petition for a retrial.

案件重审要求。

And furthermore, he released Mr. Carrillo

不仅如此，他当庭释放了 Carrillo 先生

so that he could aid in the preparation of his own defense

让他能够在检方再次对他提出起诉的时候

if the prosecution decided to retry him.

为自己的辩护工作提供帮助。

Which they decided not to.

检方最终放弃了起诉。

He is now a freed man. (Applause)

他终于自由了。（掌声）

(Applause)

（掌声）

This is him embracing his grandmother-in-law.

这是他拥抱他女友外婆时的照片。

He -- His girlfriend was pregnant when he went to trial,

他的女友在他入狱时已经怀孕，

right? And she had a little baby boy.

她后来产下一个男婴。

He and his son are both attending Cal State, Long Beach

他和他的儿子现在都在加州大学

right now taking classes. (Applause)

长滩（Long Beach）分校求学。（掌声）

And what does this example --

通过这个案例

what's important to keep in mind for ourselves?

我们应该牢记住什么？

First of all, there's a long history of antipathy

首先，在美国司法审判的历史中

between science and the law

法律界和科学界长期处于

in American jurisprudence.

相互分离的状态。

I could regale you with horror stories of ignorance

作为一名尝试将科学引入法庭的

over decades of experience as a forensic expert

鉴证专家，在多年的工作经历中，

of just trying to get science into the courtroom.

目睹了无数因愚昧导致的可怕故事。

The opposing council always fight it and oppose it.

抗诉方始终反对并对抗着这种愚昧。

One suggestion is that all of us become much more

我的建议是我们所有人

attuned to the necessity, through policy,

都应该掌握必须的知识，

through procedures,

建立规章制度

to get more science in the courtroom,

让司法审判更加科学化

and I think one large step toward that

而我认为要达到这个目标

is more requirements,

需要有大的改变才行

with all due respect to the law schools,

在完全尊重法学院需要的基础上,

of science, technology, engineering, mathematics

为每个学法律的学生开设理科科目,例如科学,

for anyone going into the law,

技术,工程,数学等课程,

because they become the judges.

因为他们将成为未来的法官。

Think about how we select our judges in this country.

回想一下这个国家是如何选拔法官的。

It's very different than most other cultures. All right?

跟别的国家有很大的不同，对么？

The other one that I want to suggest,

我的另一个建议是，

the caution that all of us have to have,

我们每个人都需要警醒自己，

I constantly have to remind myself,

我也一直警醒着我自己

about just how accurate are the memories

我们如此的相信自己的记忆，

that we know are true, that we believe in?

但是记忆究竟有多准确可靠？

There is decades of research,

研究结果已经发表几十年了,

examples and examples of cases like this,

还是有无数这样的案例

where individuals

人们非常

really, really believe. None of those teenagers

非常相信自己的记忆。

who identified him

那些少年

thought that they were picking the wrong person.

从未想过他们指认错了人。

None of them thought they couldn't see the person's face.

没有一个人想过，其实他们不可能看清凶手的脸

We all have to be very careful.

我们每个人就应该万分小心

All our memories are reconstructed memories.

我们所有的记忆都是大脑重新构造出来的

They are the product of what we originally experienced

它是我们当时的经历和自那之后

and everything that's happened afterwards.

所有经历的大杂烩产物。

They're dynamic.

记忆是动态的，

They're malleable. They're volatile,

记忆是可变的，是不稳定的，

and as a result, we all need to remember to be cautious,

所以，我们都应该警惕

that the accuracy of our memories

我们记忆的准确性

is not measured in how vivid they are

跟回忆的是否生动无关

nor how certain you are that they're correct.

跟你自己是否相信无关

Thank you. (Applause)

谢谢大家。（掌声）