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The New Science of Eyewitness Memory | John Wixted | TED
The New Science of Eyewitness Memory | John Wixted | TED
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0:04
Imagine for a moment that you're absolutely certain
0:07
about the person you saw commit a crime.
0:10
You're so confident,
0:12
you'd be willing to testify about it under oath in a court of law.
0:16
Your memory is strong,
0:18
crystal clear, absolutely unshakable.
0:22
But now imagine that that same memory, though it feels 100 percent true,
0:27
is actually false
0:29
and could send an innocent person to prison,
0:31
maybe even to death row.
0:34
This is the complex and sometimes heartbreaking world of eyewitness memory.
0:39
But for decades, we've been telling ourselves a story about eyewitness memory
0:42
that itself may not be entirely true.
0:46
Most of you have probably heard cautionary tales
0:48
about how wildly unreliable eyewitness testimony can be.
0:53
You may have heard about famous cases
0:55
like the case of Ronald Cotton,
0:57
where Jennifer Thompson, a rape victim,
1:00
misidentified him as her attacker.
1:02
As she would later recall her testimony from his criminal trial,
1:07
"I was absolutely, positively,
1:09
without a doubt certain that he was the man who raped me
1:12
when I got on that witness stand.
1:13
And nobody was going to tell me any different."
1:16
The jury understandably found her testimony convincing.
1:20
Cotton was found guilty and sentenced to life in prison.
1:25
But Ronald Cotton did not rape Jennifer Thompson.
1:28
Instead, it was a known rapist prowling her neighborhood that night.
1:32
Cotton spent almost 11 years in prison
1:35
before DNA testing finally proved his innocence
1:38
and revealed the identity of the true rapist,
1:41
a man named Bobby Poole.
1:44
Jennifer Thompson's testimony was sincere, but her memory was wrong.
1:49
DNA exoneration cases just like this one,
1:52
involving confident misidentifications,
1:54
have happened literally hundreds of times,
1:57
leading many to seriously question the reliability of eyewitness memory.
2:03
But wrongful convictions like these are not the only reason
2:06
why most people think eyewitness memory is unreliable.
2:09
For years, scientific research has also painted a damning picture
2:12
of human memory.
2:14
Starting in the 1970s,
2:15
scientists like Elizabeth Loftus
2:18
began to show how shockingly easy it is to manipulate memory.
2:22
In groundbreaking studies,
2:24
she and others implanted false memories in adults
2:27
of having been lost in a shopping mall as a child,
2:30
or as having been attacked by a vicious animal,
2:33
even though these things never actually happened.
2:37
Findings like these seem to confirm our worst fears.
2:39
Memories are not like video recordings.
2:42
They're more like evidence from a crime scene,
2:46
collected by people without gloves,
2:49
distorting and contaminating it with every touch.
2:53
This message from science
2:56
reinforced the message from the wrongful convictions,
2:58
and the conventional wisdom was set in stone for decades.
3:02
The legal system should not trust eyewitness memory.
3:05
It's just too unreliable.
3:08
But here's where the story takes an unexpected turn.
3:11
What if the problem is not so much about how unreliable eyewitness memory is,
3:16
because of how easily contamination can create false memories,
3:21
and more about how and when we test the witness's memory.
3:26
Think about forensic evidence like DNA or fingerprints.
3:30
Everybody knows that forensic evidence can be contaminated
3:33
and end up implicating an innocent person,
3:37
much like contaminated memory can.
3:39
But we don't just dismiss forensic evidence for that reason.
3:43
Instead, we collect it as early as possible in the police investigation
3:48
before it's contaminated.
3:51
Why do we do that?
3:53
It's because reliable information comes from analyzing uncontaminated evidence,
3:58
not contaminated evidence.
4:00
And the exact same principle applies to memory evidence.
4:05
Collect it early, before it's contaminated.
4:10
An eyewitness’s memory of whether or not the police suspect
4:13
is the person who they saw commit the crime
4:16
can be highly reliable,
4:19
but only if the witness's memory is uncontaminated,
4:22
not after it's been contaminated.
4:25
And scientists now agree
4:26
that even the first test contaminates the witness's memory for a given suspect.
4:32
If the suspect’s innocent, for example,
4:35
it's the first time the witness is seeing his face,
4:39
and this is happening at a time
4:40
when the witness is actively thinking about the crime.
4:43
So even if the witness says,
4:45
"No, that's not the guy who did it,"
4:48
this is how the innocent suspect’s face first becomes associated with the crime
4:53
in the witness's memory.
4:55
That's contamination.
4:57
You can’t keep that from happening,
5:00
and you can’t put the witness’s memory back the way it was.
5:04
So focus on the first uncontaminated memory test
5:07
early in the police investigation,
5:10
not the last, thoroughly contaminated test
5:13
that happens at the criminal trial one, two, or even three years later.
5:19
Unfortunately, courts tend to do the reverse,
5:22
placing their faith in the last test of memory at trial
5:26
while all but ignoring the critical first test.
5:30
This is a seriously underappreciated problem.
5:37
Well, with that in mind,
5:38
let's take a closer look at how the police conduct
5:40
that all-important first test of a witness’s uncontaminated memory.
5:48
In the days or weeks after a crime,
5:50
the police might find a suspect,
5:52
a person who they think may have committed the crime,
5:55
and they'd like to show him to the witness
5:57
to see if they have the right guy.
5:59
They could just hand the suspect's photo to the witness and ask,
6:03
is this the guy who did it?
6:06
The problem is, that would be suggestive,
6:08
because it would reveal to the witness who the police think
6:10
may have committed the crime.
6:12
To test memory in a less suggestive way,
6:15
the police will often show the witness a whole set of six photos.
6:20
It's called a six-pack photo lineup.
6:22
One photo is of the suspect,
6:25
and the others are of similar-looking individuals
6:28
who the police know are innocent.
6:30
That way, they can still show the suspect's photo to the witness,
6:34
but without revealing who they think committed the crime.
6:37
It's a much fairer way to test memory,
6:39
and it becomes fairer still when other recommended practices are followed.
6:44
Such as letting the witness know
6:46
that the perpetrator who they saw commit the crime
6:49
may or may not be among these photos.
6:51
And the officer who's administering these photos to the witness
6:54
should not even know who the suspect is
6:57
to avoid unintentionally influencing the witness’s choice.
7:02
When it's done this way, it becomes a pure test of the witness's memory,
7:06
and this is where things start to get interesting.
7:09
About 10 years ago, work from my lab,
7:11
published in strong, high-impact scientific journals,
7:17
first reported that a confident identification of a suspect
7:21
from an initial photo line-up is highly reliable.
7:26
Big surprise.
7:28
Not unreliable.
7:31
For a scientific field that has spent decades
7:33
cautioning the legal system
7:35
about the unreliability of eyewitness memory,
7:38
these findings were not easy to enthusiastically embrace.
7:44
But almost all of the recent science finds that an initial,
7:47
confident identification is much more reliable
7:50
than the field previously thought.
7:52
Not infallible, of course, but certainly not unreliable.
7:58
These new scientific findings raise an interesting question
8:01
about the DNA exoneration cases that I told you about earlier.
8:05
The ones where we know that on the last test of their memory,
8:09
at the criminal trial,
8:10
witnesses confidently misidentified an innocent person
8:14
contributing to a wrongful conviction.
8:17
The question is: What did those witnesses do
8:20
the very first time their memory was tested for that same person?
8:25
And when you look into that,
8:27
you find they usually did not confidently misidentify
8:30
the innocent suspect at that time.
8:32
The problem is, nobody listened to them.
8:35
Remember Jennifer Thompson?
8:38
She struggled with the initial photo lineup a few days after the crime.
8:43
Narrowing it down to two pictures,
8:46
wavering hesitantly between them for literally minutes
8:49
before finally landing on Ronald Cotton's face and saying,
8:52
"I think it's him."
8:55
It was obviously inconclusive identification,
8:57
full of doubt and indecision.
9:01
By the time of his criminal trial, after much memory contamination,
9:05
that her doubts were gone and she became absolutely, positively,
9:08
without a doubt certain
9:09
that Ronald Cotton was the man who raped her.
9:12
If they had known then what we know now,
9:15
focus on the first test,
9:17
where, in this case, you find a completely inconclusive identification,
9:21
it seems likely that Ronald Cotton never would have been wrongfully convicted
9:25
in the first place.
9:26
And that's the point.
9:29
Alright, here's where the story takes another interesting turn.
9:33
On this first test using a photo lineup,
9:35
witnesses often don't even tentatively identify the suspect
9:39
the way that Jennifer Thompson tentatively identified Ronald Cotton.
9:43
Instead, at a time when the witness's memory of the perpetrator is as fresh
9:47
and strong and uncontaminated as it will ever be,
9:51
the witness looks at the photos,
9:52
including the photo of the suspect, and says,
9:56
"None of these guys match my memory of the person who committed the crime."
10:00
In other words, the witness rejects the lineup,
10:03
providing clear evidence that the suspect in the lineup is innocent.
10:09
You see, this is absolutely the key point.
10:13
The first test of an eyewitness's uncontaminated memory
10:18
can provide reliable evidence pointing in either direction:
10:22
towards guilt or innocence,
10:25
depending on how the test turns out.
10:27
And when the witness rejects the lineup,
10:29
it provides reliable evidence pointing in the direction
10:34
of the suspect's innocence.
10:36
Yet many witnesses who reject an initial photo lineup,
10:40
after their memory becomes contaminated,
10:43
will show up at a criminal trial a year or two later,
10:46
unaware that their memory is contaminated,
10:49
and now confidently identify the very same person
10:52
they initially rejected.
10:54
Half the time, they don't even remember doing that,
10:56
it was so long ago.
10:58
These defendants are often convicted, sentenced to long prison terms,
11:02
and are now behind bars.
11:04
And unlike Ronald Cotton,
11:08
they do not have any DNA evidence to prove their innocence.
11:12
But what they do have is a new message
11:16
from the world of memory science that can help to do that.
11:19
And ironically,
11:21
in a complete mind flip,
11:24
it's reliable evidence of innocence
11:26
from the memory of an eyewitness the first time they were tested.
11:31
Consider the case of Miguel Solorio.
11:34
He was arrested in 1998 for murder.
11:37
But on the first test, four witnesses rejected his photo lineup.
11:43
Nobody paid any attention to that.
11:45
More than a year later,
11:46
two of those same witnesses showed up at his criminal trial
11:49
and identified him as the shooter in front of a judge and jury.
11:53
He was convicted and sentenced to life in prison
11:56
without the possibility of parole.
11:59
Miguel spent 25 years of his life,
12:03
from age 19 to age 44,
12:06
behind bars,
12:07
before finally being exonerated in late 2023,
12:12
with the help of the new science that I'm telling you about today:
12:16
focus on the first uncontaminated test.
12:20
As tragic as Miguel's story is,
12:23
at least the new science helped to overturn his conviction
12:26
before he spent his entire life in prison.
12:30
But others with a similar story remain behind bars as we speak.
12:34
And some of them,
12:36
their lives are hanging in the balance.
12:39
Consider the case of Charles Don Flores.
12:42
He, too, was arrested for murder in 1998.
12:45
There was one witness in this case.
12:48
On the day of the crime,
12:49
she told the police that she saw a white male with shoulder-length hair
12:53
go into her neighbor's house
12:54
shortly before the murder occurred.
12:57
A couple days later, she goes back to the police station.
13:00
They hypnotize her.
13:01
It's always dicey, but she stuck to her story.
13:04
She said it's a white male with shoulder-length hair.
13:07
The police asked her to make a composite sketch, so she did.
13:11
Came out to be a white male with shoulder-length hair,
13:13
just like she said.
13:15
Now keep in mind, this is very early in the police investigation.
13:19
This is a time when her memory of the perpetrator is as fresh and strong
13:23
and uncontaminated as it will ever be.
13:27
And this is what the perpetrator looks like.
13:30
But the police suspected Charles Don Flores,
13:32
a Hispanic man with short hair.
13:35
And for some inexplicable reason,
13:37
put his photo in a photo lineup and showed it to the witness.
13:43
This is still early in the police investigation.
13:46
This is the all-important first test of a witness's uncontaminated memory
13:50
for the suspect, Charles Don Flores.
13:53
The witness looked at this photo lineup,
13:57
didn't see any white males with shoulder-length hair,
14:00
and quite understandably rejected it,
14:03
providing clear evidence that Flores is innocent.
14:07
Fast forward to his criminal trial a year later,
14:10
and you can probably guess how this story turns out.
14:13
Now the witness is more than 100 percent certain that it was Charles Don Flores
14:17
she saw go into her neighbor's house on the day of that murder.
14:22
The jury was convinced, he was found guilty
14:25
and sentenced to death.
14:27
He's been on death row for more than 25 years,
14:30
where he remains to this day.
14:33
And in all those years,
14:36
no jury even heard what the witness did
14:39
on the first test of her uncontaminated memory,
14:42
much less about the new scientific consensus,
14:45
emphasizing the importance of focusing on that first test,
14:48
because that's where the reliable information is.
14:54
So, you see, this isn't just an academic exercise.
14:57
It's about exonerating the wrongfully convicted,
15:00
some of whom are on death row,
15:02
and about preventing wrongful convictions from happening in the first place.
15:06
It's about understanding that memory is not an enemy to be distrusted,
15:11
but a complex tool that, when properly used,
15:13
can serve the cause of justice.
15:16
The reforms that need to be made going forward seem pretty clear.
15:20
Number one, in both police investigations and legal proceedings,
15:25
prioritize the first test of the witness's uncontaminated memory,
15:29
because that's where the reliable information is.
15:32
Number two, at the same time,
15:34
de-emphasize confident suspect identifications
15:39
made by a witness who earlier rejected that same face
15:42
because that likely reflects memory contamination, not the truth.
15:46
And number three,
15:47
to get these reforms underway, educate legal professionals,
15:51
police chiefs,
15:53
defense attorneys, prosecutors, judges
15:56
about the new science of eyewitness memory.
16:00
Over the last couple of years,
16:01
my colleagues and I have been doing just that,
16:03
reaching out to defense attorneys and prosecutors alike
16:06
to bring this new understanding to the legal system.
16:09
We find that initially, at least,
16:11
defense attorneys are alarmed by this new message
16:14
because they're uncomfortable with the idea that eyewitness memory
16:17
can ever be reliable.
16:20
To them, listening to what an eyewitness has to say,
16:23
even on the very first test of their uncontaminated memory,
16:26
is just a recipe for another wrongful conviction.
16:29
And prosecutors,
16:31
they're equally alarmed, but for the opposite reason.
16:34
To them, not listening to a witness
16:36
who makes a confident suspect identification
16:39
after previously rejecting that same face
16:43
sounds like a recipe for letting the guilty walk free.
16:47
So we've managed to bring both sides of the aisle together in a way,
16:52
to both the defense and the prosecution our new message sounds dangerous.
16:57
But it's not dangerous.
16:58
It's just how memory works.
17:01
To better serve the cause of justice,
17:03
both sides and all of us have to follow the science by listening to memory
17:09
when it most reliably speaks the truth.
17:13
It will become a more just world if we can find a way to do that.
17:18
Thank you.
17:20
(Applause)
The New Science of Eyewitness Memory | John Wixted | TED - Video học tiếng Anh
