Forensic neuroscience can mean life or death - Dr. Scott Fraser at TEDxUSC

Dr Scott Fraser discusses a drive-by shooting in which witness evidence turned out to be flawed as in many other similar cases. He considers the problems of memory and looks at how the quality of light at a crime scene can be scientifically investigated.

The murder happened a little over
21 years ago on January 18th 1991.

In a small bedroom community
of Lynwood, California,

just a few miles southeast of Los Angeles.

Father came out of his house to tell
his teenage son and his five friends

that it was time for them
to stop horsing around

on the front lawn and on the sidewalk,

to get home,
finish their school work,

prepare themselves for bed.

And as the father was administering these
instructions, a car drove by, slowly.

And just after it passed the father
and the teenagers, a hand went out

from the front passenger window
and Bam! Bam!, killing the father.

And the car sped off.

The police investigating officers
were amazingly efficient.

They considered all the usual culprits,

and in less than 24 hours
they had selected their suspect;

Francisco Carrillo,
a seventeen-year-old kid,

who lived about two or three blocks away
from where the shooting occurred.

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

and the day after the shooting
they showed it to one of the teenagers

and he said, "That's the picture, that's
the shooter I saw that killed the father."

That was all a preliminary hearing judge
had to listen to,

to bind Mr Carrillo over
to stand trial for a first-degree murder.

In the investigation that followed
before the actual trial,

each of the other five teenagers was shown
photographs, the same photo array.

The picture that we best can determine
was probably the one that they were shown

in the photo array is in your bottom
left-hand corner of these mugshots.

The reason we're not sure absolutely

is because of the nature of evidence
preservation in our judicial system.

But that's another whole
TEDxTalk for later.

So, at the actual trial
all six of the teenagers testified

and indicated identifications
they had made in the photo array.

He was convicted,
he was sentenced to life imprisonment,

and transported to Folsom prison.

So what's wrong? Straightforward,
fair trial, full investigation.

Oh yes, no gun was ever found.

No vehicle was ever identified

as being the one in which
the shooter had extended his arm,

and no person was ever charged with
being the driver of the shooter's vehicle.

And Mr Carrillo's alibi?

Which of those parents
here in the room might not lie

concerning the whereabouts of your son or
daughter in an investigation of a killing?

Sent to prison,
adamantly insisting on his innocence,

which he has consistently for 21 years.

So what's the problem?

The problems actually for
this kind of case come manifold

from decades of scientific research
involving human memory.

First of all we have
all the statistical analysis

from the Innocence Project work,
where we know

that we have, what,
250, 280 documented cases now,

where people have been
wrongfully convicted

and subsequently exonerated,
some from death row,

on the basis of later DNA analysis.

And you know that over three-quarters
of all of those cases of exoneration

involved only eye-witness
identification testimony

during the trial that convicted them.

We know that eye-witness identifications
are fallible

The other comes from
an interesting aspect of human memory,

that's related to various brain functions,

but I can sum up for the sake of brevity
here in a simple line:

the brain abhors a vacuum.

Under the best of observation conditions,
the absolute best,

we only detect, encode
and store in our brains,

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

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

So now when it's important

for us to be able to recall
what it was that we experienced,

we have an incomplete, we have
a partial store, and what happens?

Below awareness, with no requirement
for any kind of motivated processing,

the brain fills in information
that was not there, not originally stored,

from inference, from speculation,
from sources of information

that came to you as
the observer after the observation.

But it happens without awareness such
that you aren't cognizant of it occurring.

It's called reconstructed memories.
It happens to us

in all the aspects of our lives,
all the time.

Let me ask you to consider
the horrific events of 9/11.

Think about when you first got
the information about this catastrophe,

how you felt and more importantly,

when was first time you saw
the second trade tower imploding collapse,

after the first trade tower had gone down?

If you're like most Americans,
myself included,

you have a very clear memory

that you saw the first tower come down
and then you saw

the second tower finally collapse
after the other plane crashed into it

within an hour or two afterwards.

I remember vividly where I was.
I was down at LAX,

at the satellite terminal
for American Airlines,

waiting to get on an airplane
to fly to San Diego.

Of course, all the air traffic was ceased.

And so I had nothing to do but
to sit and watch the television monitors

with all of the news broadcasts
over and over and over again.

Of the horrendous events and I know I saw
that second trade tower come down

an hour or two after the first.

And all of the research we have indicates
that most Americans too,

except for a few people
that live in certain places in New York.

And you know something?
That's a totally false memory.

It could not be something you experience,

there was absolutely no media footage

of the second trade tower collapsing
until over 24 hours after the event.

But in fact you know
intellectually, cognitively,

that they did occur fairly close in time.

You did know about and see the first one,
you did see the second one;

but you didn't see it until
over a day later at the earliest.

But the brain without you being aware
has pulled them together,

and you believe you saw them
very close in time.

It is a reconstructed memory,
not an accurate memory.

No matter how vivid,
no matter how sure you are,

it was those two considerations
among others,

reconstructed memory, the fact
about the eye-witness fallibility,

that was part of the instigation
for a group of appeal attorneys

led by an amazing lawyer,
named Ellen Eggers,

to pool their experience and accounts
together and petition the superior court

for a retrial for Francisco Carrillo.

They retained me
as a forensic neurophysiologist

because I had expertise

in eye-witness memory identification,
which obviously makes sense for this case,

but also because I'd expertise and testify
about the nature of human night vision.

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

Well, when you read through
the case materials in this Carrillo case,

one of the things
that suddenly strikes you is that

the investigating officers
said the lighting was good

at the crime scene, at the shooting.

All the teenagers testified
during the trial

that they could see very well.

But this occurred in mid-January,
in the northern hemisphere,

at 7 pm at night.

So when I did the calculations,

at that location on Earth at the time
of the incident of the shooting,

it was well past the end of civil twilight
and there was no moon up the night.

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

is what you see on the screen right here.

The only lighting in that area had to come
from artificial sources.

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

with photometers,
with various measures of illumination

and various other
measures of power perception

along with special cameras
and high-speed film;

take all the measurements and record them,
and then take photographs.

and this is what the scene looked like
at the time the of the shooting

from the position of the teenagers

looking at the car going by and shooting.

This is looking directly
across the street,

remember the investigating officer's
report said the lighting was good;

teenagers said they could see very well.

This is looking directly across the street
from where they were standing.

This is looking down to the east
where the shooting vehicle sped off.

And this is the lighting directly behind
the father and the teenagers.

As you can see it is at best poor.

No one is gonna call this
well-lit, good lighting

and in fact as nice as these pictures are
and the reason we take them

is I knew I was going
to have to testify in court.

And a picture is worth
more than a thousand words

when you're trying to communicate numbers,
abstract concepts like lux,

the international measurement
of illumination,

the Ishihara color
are color perception test values.

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

in those aspects of science and that,

they become salamanders
in the noonday sun.

It's like talking about
the tangent of the visual angle;

their eyes just glaze over.

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

a good communicator and that's part
of the reason why we take the pictures

to show not only where
the light sources are

and what we call the spill,
the distribution,

but also so that
it's easier for the trier of fact

to understand the circumstances.

So these are some of the pictures
that in fact I use when I testify.

But more importantly were to me,
the scientists, are those readings,

the photometer readings,
which I can then convert

into actual predictions
of the visual capability of the human eye

under those circumstances.
And from my readings

that I recorded at the scene
under the same solar and lunar conditions

at the same time and so on and so forth,

I could predict that there would be
no reliable color perception

which is crucial for face recognition.

And that there would
only be scotopic vision

which meant there'd be
very little resolution

which we call boundary or edge detection,

and furthermore because the eyes would
have been totally dilated

under this light,
the depth of field,

the distance at which you can
focus and see details

would have been less
than 18 inches away.

I testified to that to the court

and while the judge was very attentive,
it had been a very, very long hearing

for this petition for a retrial.

And as a result I'd noticed
out of the corner of my eye

that I thought that maybe the judge
was going to need a little more of a nudge

than just more numbers.

And here I became a bit audacious
and I turned and I asked the judge,

I said, "Your honor, I think you should
go out and look at the scene yourself."

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

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

that he said, "Yes, I will"
a shocker in American jurisprudence.

So in fact we found
the same identical conditions,

we reconstructed the entire thing again,

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

to protect him in this community.
(Laughter)

We had him stand actually
slightly in the street, so closer

to the shooter vehicle
than the actual teenagers were.

So he stood a few feet from the curb

toward the middle of the street.

We had a car that came by,

same identical car
as described by the teenagers.

It had a driver and a passenger,

and after the car had passed the judge by,

the passenger extended his hand,

pointed it back to the judge,

as the car continued on,
just as the teenagers had described it.

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

we thought the sheriff's department
would probably question the necessity

for that kind of realism.

So we had a black object in his hand that
was similar to the gun that was described.

He pointed, Bam!
And this is what the judge saw.

This is the car
30 feet away from the judge.

There's an arm sticking out
of the passenger side

and pointed back at you.
That's 30 feet away.

Some of the teenagers
just said that in fact

the car was 15 feet away
when it shot.

There's 15 feet.

At this point I became a little concerned.

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

He was totally stoic.

I couldn't see a twitch of his eyebrow,

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

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

And after he looked at this re-enactment,

he turned to me and he says, "Is there
anything else you want me to look at?"

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

by the scientific measurements
that I had in my pocket,

and my knowledge that they are accurate,

or whether it was just sheer stupidity,
which is what the defense lawyers thought

when they heard me say, "Yes Your Honor,
I want you to stand right there.

I want the car to go around
the block again.

And I want it to come, and I want it
to stop right in front of you,

three to four feet away
and I want the passenger

to extend his hand with a black object,
point right at you,

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

And that's what he saw.
(Laughter)

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

all the dominant lighting
is coming from the north side

which means that the shooter's face
would have been photo occluded,

would have been backlit.
Furthermore, the roof of the car

is causing what we call
a shadow cloud inside the car,

which is making it darker.

And this is three to four feet away.

Why did I take the risk?

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

Three to four feet; it might as well
have been a football field away.

This is what he saw, went back,

there was a few more days of evidence
that was heard.

At the end of it, he made the judgment

that he was going to grant
the petition for a retrial,

and furthermore he released Mr Carrillo

so he could aid in the preparation
of his own defense

if the prosecution decided to retry him.

Which they decided not to.
He is now a freed man.

(Applause)

This is him embracing here
his grandmother-in-law.

His girlfriend was pregnant
when he went to trial

and she had a little baby boy.

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

right now, taking classes.

(Applause)

What does this example, what's important
to keep in mind for ourselves?

First of all there's a long history
of antipathy between science and the law

in American jurisprudence.

I could regale you with
horror stories of ignorance.

Over decades of experience
as a forensic expert,

of just trying to get science
into the courtroom,

deposing council
always fighting an opposer.

One suggestion is that all of us
become much more attuned

to the necessity, through policy,
through procedures,

to get more science in the courtroom.

And I think one large step
toward that is more requirements,

with all due respect to the law schools,

of science, technology,
engineering, mathematics,

for anyone going into the law
because they become the judges.

Think about how
we select our judges in this country,

it's very different
than most other cultures.

The other ones I wanna suggest,
the caution that all of us have to have,

I constantly have to remind myself

about just how accurate are the memories
that we know are true,

that we believe in.

There is decades of research,
examples and examples of cases like this,

where individuals really, really believe.

None of those teenagers
who identified him

thought that they were picking
the wrong person,

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

We all have to be very careful.

You just saw a marvelous film
about all kinds of complexities of memory,

It is an enormously confusing

and difficult set of processes
and principles that are involved.

All our memories
are reconstructed memories.

They are the product
of what we originally experienced

and everything that's happened afterwards.

They're dynamic, they're malleable,
they're volatile, and as a result

we all need to remember to be cautious.

That the accuracy of our memories
is not measured in how vivid they are

nor how certain you are
that they're correct.

I'm sure I saw the second trade tower
collapse an hour later,

but I know it could not have happened.

Thank you.

(Applause)