Transcriber: Riley Syrocki Autery Reviewer: Maria Pericleous
I’d like to tell you a story.
It’s a true story about a murder
and about a machine that has poisoned the justice system
and changed the way we think about the truth.
You are probably familiar with this machine.
You might have seen it on daytime talk shows,
or on true crime series on Netflix.
It taps into something that everyone does,
and exploits the fear that everyone has.
It’s called the lie detector.
But the truth about it is just as shocking
as any TV show.
100 years ago this weekend, on the 30th of May 1922,
a woman called Anna Wilkins was driving home from a camping trip
with her husband, Henry, and their two kids.
They were heading north towards their home in San Francisco
and they had just got to the edge of the city,
when Henry noticed a car following them.
It was dark blue, with big round headlights.
Henry was driving, and he moved over to let the car go past, but it didn’t.
Instead, the car kept following them,
getting closer and closer,
as they headed downhill into the city.
Finally in the Sunset District, on the edge of San Francisco,
the car swerved towards them,
forcing Henry to the side of the road.
Henry and Anna’s car slammed into the curb,
and when Henry looked up,
there was a man standing at his window, pointing a gun at him.
The man was shouting at Henry, asking for money.
Henry handed over his wallet, but the man didn't leave.
Instead, the man started asking for Anna’s jewelry as well,
and that made Henry angry.
Henry started shouting at the bandit.
He said, “Haven’t you taken enough?”
Then Henry reached for his own gun, he had a gun in the side pocket of his car,
but he was too slow.
The bandit fired a bullet into the car,
but the bullet missed Henry and hit his wife Anna instead.
The shooter ran back to his own car and sped away.
Henry looked at his wife,
she was bleeding from a wound in her chest,
and he raced to a hospital as fast as he could,
but, he was too late.
Anna died before surgeons could operate on her.
When doctors told Henry the news, he was so upset that he collapsed.
Or, at least that’s the story that Henry told the police.
But over the following weeks, a different version started to come out.
It turned out that Henry and Anna did not have a happy marriage.
Henry was violent,
and a few weeks before she died, Anna had filed for a divorce.
On top of that, the evidence that Henry had given to police
didn’t match what other witnesses had said.
He had told the police that the car chasing him
was red, for example,
but all the other witnesses seemed to think that it was blue.
A few days after Anna’s murder, police arrested their two main suspects,
but when they showed these suspects to Henry in an identity parade,
he said he didn’t recognize either of them.
A few days later, though,
journalists found out that Henry had actually worked
with one of the suspects a few years previously.
The police were starting to suspect that Henry might be lying,
that maybe he was somehow involved in his wife’s death,
but they had no evidence.
So in order to find out whether this really was a robbery gone wrong,
or something more sinister, they turned to a brand new machine,
a machine that had just been invented
in the nearby town of Berkeley, California,
and which was already taking America by storm.
It was called the polygraph machine, also known as the lie detector.
The polygraph was invented in 1921
by a rookie police officer called John Larson.
Policing in those days was a brutal profession.
Officers kept order with their fists and with clubs
rather than with their wits.
But that was starting to change in Berkeley
thanks to a visionary Police Chief called Auguste Vollmer.
Vollmer had brought scientific methods into policing for the first time.
He used fingerprinting, gunshot analysis and crime scene photography.
He also started hiring young men from the University of Berkeley
to work in the police department.
The newspapers called these men college cops.
John Larson was one of these college cops, but he wasn’t a fresh-faced undergraduate.
Larson was already a trained scientist.
He had a Ph.D. in physiology, and he had joined the police
because he wanted to get some real-world experience
before he embarked on a career in criminology.
Larson’s driving force
was to try and predict crimes before they happened.
He wanted to end the brutal tactics used by his police colleagues.
He wanted to bring in a new and more enlightened way of policing.
So, Larson was really pleased when his boss called him in one day
with what he thought was an interesting assignment.
Vollmer had read a research paper
about how blood pressure changes when people tell untrue stories,
and he asked John Larson to try and develop
a way of tracking and measuring this change,
so that it could be used during interrogations.
Larson went away to work on this, and a few weeks later
he’d come up with an ugly device that combined blood pressure cuffs
with tubes that wrapped round the chest to measure breathing,
and two pens that scratched it all onto a moving roll of paper.
This was the first polygraph machine,
the lie detector that would soon spread all over the world.
A week after Henry's wife was shot,
He was still refusing to admit that he had anything to do with it.
But there was growing evidence
that he had actually lied to police about what had happened that night.
So, in June 1922,
the San Francisco Police Department arranged for John Larson
to conduct a lie detector test on Henry Wilkins
to try and get to the truth about his role in his wife’s murder.
The polygraph is supposed to work like this.
So the examiner asks the suspect two different types of questions.
Some of them are control questions, like, is your name Henry?
Others are target questions, like,
did you steal the car, or did your shoot your wife?
The idea is that people should be under more emotional stress when they're lying,
and therefore they should show more of a reaction
to questions about the crime.
Their blood pressure and their breathing rate should change.
And so by comparing their answers to these target questions
to their answers to the control questions,
you should be able to spot a liar.
But there’s a big problem with this: we are all different.
Something that stresses you out
might have absolutely no effect on the person sitting next to you.
In the film Pinocchio, the puppet’s nose gets longer every time he tells a lie.
But, in the real world, lying isn’t that neat.
Lying isn’t that obvious.
There is no such thing as a Pinocchio’s nose.
Some people claim to be able to tell when someone is lying
by the way they speak or the way they move their eyes
but there is no single telltale sign of lying
that works for everyone all of the time.
That’s why we’re all so terrible at catching liars.
On average, we can spot them just 54% of the time.
And despite what you might have heard,
the polygraph isn’t much better than this.
One estimate puts the polygraph’s accuracy at just 65%.
That isn't much better than tossing a coin.
And that makes so-called lie detectors dangerous
because, although they can help police officers get confessions,
they can also lull them into a false sense of security,
they can coerce people into falsely confessing,
or they can allow criminals to walk free.
For almost as long as the polygraph has been around,
people have been figuring out ways to beat it.
These are called countermeasures,
and they usually work by exaggerating
your body’s response to the control questions.
If you amp up your body’s reaction to these questions,
when the target questions come around
the theory is the examiner won’t be able to tell the difference.
It will look like you were just really nervous,
and that you might be telling the truth.
You can do this by clenching your muscles, by pinching yourself,
or by stepping on a pin that you’ve hidden in your shoe.
Anything that will get your pulse and blood pressure going up,
so when the comparisons come around, there’s no way to tell the difference
between when you’re lying and when you’re pinching yourself, would work.
Some people have tried to beat the polygraph by taking drugs
or by drinking loads of coffee before a test.
Other people might just naturally show no emotion.
Some researchers think that psychopaths
might be essentially immune to lie detector tests.
When the lie detector works, it’s because people think that it works,
not because of the machine itself.
They’re so scared of the supposed power of the machine,
that they break down and confess.
Sometimes it works so well
that people confess to things that they haven’t even done.
It didn’t take long for police officers to realize
that they could get people to confess
even if they didn’t actually have access to a lie detector.
There’s a great story from the 80s from Detroit, where police
were extracting confessions from suspects using a photocopier machine.
They would put a suspect’s hand on the machine, press a button
and a piece of paper would shoot out, with the words “He’s lying” printed on it.
(Laughter)
More recently, the US Supreme Court
heard evidence about a man who was tricked into confessing.
Officers put a sieve on his head, attached some wires to it,
and told him it was a lie detector.
Back in 1922, John Larson spent hours interrogating Henry Wilkins
at The Hall of Justice in San Francisco,
asking him questions about his wife’s death
over and over again.
But Henry didn’t crack, he passed his lie detector test.
But when he left the police station after the test,
Henry was being followed,
and he went straight to a secret meeting with the brother of one of the suspects.
So he had just spent hours
telling police he’d never met these men before in his entire life,
and straight after the lie detector test
he goes to a secret meeting with their brother.
It looked like Henry Wilkins had beaten the lie detector.
His case went to a trial, it went to a retrial,
and he beat those too!
He never faced justice for his role in his wife’s death.
John Larson was distraught, as he watched all this unfold.
He was still convinced that Henry was lying,
and he was so desperate to get to the truth
that he actually abandoned his scientific impartiality.
Larson made friends with Henry Wilkins after his trial.
He helped Henry move house, he helped Henry get a new job.
And he somehow convinced Henry to take another polygraph test.
And guess what? Henry passed again.
So, the Henry Wilkins case has to go down as a huge failure for the lie detector.
It exposed the truth about the machine.
But 100 years later, the lie detector is being used more than ever.
There are still two and a half million polygraph tests a year
in the United States.
It’s used by police forces, by security services and by employers
all over the world,
even though it doesn’t work.
For 100 years, we’ve been told a lie about the power of the machine.
A lie that gets reinforced
every time you see it crack a stubborn suspect on a television show.
It’s easy to understand why.
We are living in a golden age of liars,
it’s really tempting to think that there’s a machine out there
that can catch devious criminals or unmask corrupt politicians.
But the truth is that lie detectors
are just another tool used by those very same politicians
to stamp out free speech and to oppress minorities.
And that’s exactly what’s happened with the polygraph.
To John Larson’s horror,
the lie detector quickly found a home in the military.
By the 1950s it was being used to weed out political dissidents in the United States.
And in the 1970s,
It was used by governments to target and to blackmail homosexuals.
Today, governments expand the use of lie detectors
when they want to look tough on crime.
They’re targeting migrants, they’re targeting asylum seekers.
They don’t really care whether it actually works or not,
they just want to look tough.
By the time he died,
John Larson considered his machine a Frankenstein’s monster.
He had wanted to bring in a more enlightened way of policing,
but he ended up giving the police a psychological form of torture.
He spent the rest of his life trying to undo
some of the damage that he’d done.
But Larson was too late,
because not only does the polygraph continue to grow in popularity,
In the last 20 years, history has been repeating itself.
New types of lie detector are being developed,
that use brain scans and artificial intelligence.
They claim to be able to achieve this impossible goal of catching liars.
And it almost sounds plausible.
Every day we hear amazing things about what A.I. can do,
so why shouldn’t it be able to tell if you’re lying?
But the truth is, these new technologies are just as flawed as the polygraph.
You can break them down into five types,
based on the five different types of evidence that they look for.
But they all rely on the same basic assumption,
this idea that lying is more mentally taxing
and more emotionally stressful than telling the truth.
That makes sense, lying is really hard.
You have to figure out what another person is thinking,
you have to suppress your own emotions
and you have to hold yourself back from blurting out the truth.
Being honest certainly feels easier.
It doesn’t have what psychologists call a cognitive load.
Most theories of lie detection assume that this cognitive load
leaves some evidence in our actions.
The first two types of evidence are verbal,
the things that we say, and the way we say them.
There is some evidence, for instance,
that people lying in their online dating profiles
tend to use the words “I” “me” and “my” more often.
Voice stress analysis tries to catch liars using tone of voice.
Body language is another source of potential information,
so this might be the one that attracts the most folk theories
about lie detection.
People think they can spot a liar by the way they’re standing
or if they don’t make eye contact with you when they’re talking.
The fourth type of evidence is physiological.
So there’s the polygraph, of course,
which tries to tap into blood pressure, breathing and sweat.
But there are also infrared cameras that try to analyze facial tempature.
Unlike Pinocchio, our noses might actually shrink slightly when we lie,
as warm blood flows towards the brain and away from the face.
By the 1990s and 2000s,
government funding was unlocking a new and apparently more direct route to lying,
via the brain.
So there have been two types of brain-based lie detectors
developed so far.
Some are based on EEG readings,
so suspects wear a device that measures their brain waves
and then they’re shown words or images associated with the crime.
The idea is that the culprit’s brain will recognize
those words or images that are linked to the crime,
Whereas people that are innocent won’t have that same pattern of response.
The second type of brain-based lie detection uses fMRI.
So, a person is put in a giant scanner,
and the scannar looks for blood flow inside the brain.
This is based on the idea that lying uses certain parts of your brain
more than others, and that, as those brain cells fire
they need energy, so blood will flow to those areas of the brain
to provide them with energy and you can see that on the scanner.
Now, these new technologies might sound impressive,
but researchers are already figuring out how to beat them.
And the latest development in the last few years is artificial intelligence.
So in the same way that John Larson combined different types of measurements
to make the polygraph,
some startups are combining lots of different measurements using A.I.
I saw one of these systems in action.
It uses a suspect’s voice and facial expressions,
and assigns them a score,
based on how much it thinks they’re lying.
There’s literally a dial, and it goes from red to green,
depending on how much the algorithm thinks you’re telling the truth.
Another technology measures your pupil dilation,
because that offers a clue to how hard you’re thinking.
The theory is, the harder you are thinking the more likely it is that you’re lying.
But again, you can see the flaw with this.
All of these technologies suffer from the same problems
as the polygraph machine.
The same problem that I mentioned earlier.
There is no Pinnochio’s nose.
Even if your technique works on some people,
it won’t work on everyone,
and there is no way of telling those two groups apart.
I've spent the last four years exploring these new forms of so-called lie detector
for my book, Tremors in the Blood,
and researching the history of the polygraph.
The way that these inventors talk,
the way they interact with the people they’re testing,
reminds me so much of John Larson and of Henry Wilkins.
History is repeating itself.
So if you ever find yourself strapped to a polygraph machine,
or placed inside a brain scanner,
or being watched by an all-powerful lie detecting, A.I. ,
here’s what you should do.
Think about John Larson and his fights against his own creation.
Think about all the lies you've told,
the little white lies, and the lies that have sunk so deeply into your soul
that you almost believe them yourself.
And think about the big lie.
The lie behind the box sitting on the table in front of you.
The lie detector thrives on fear and ignorance,
and the only way to beat it is by knowing the truth.
(Applause)