Transcriber: Dinh Lieu Vu Reviewer: David DeRuwe
Brian Williams was a celebrated news anchor.
He told a story to “The Late Show with David Letterman”
about a harrowing and exciting helicopter crash in Iraq.
The problem is the story wasn’t exactly true,
and his lie resulted in him being terminated from the network,
he lost his nightly news anchor job,
he was eventually reinstated, and he retired a couple of months ago,
but his deception resulted in his reputation being somewhat tarnished,
even after 28 years of excellent journalism.
When politicians or journalists
or even professional athletes that we admire lie to us,
it stings and it causes us to be more cynical.
But when people we know, people we love and trust lie to us,
it really hurts because it ruins our relationships
and it makes us less trusting in the future.
I've been a deception detection researcher for over 20 years,
and when people find out what I do for a living,
they often ask me questions like
“Is it true that liars look up to the left and truth tellers look up to the right?”
Nope, that’s not true.
“You can tell when people are lying pretty easily, right?
It’s written all over their face.”
Nope, that’s not true either.
“But when you know someone really well,
you can really tell when they’re lying, can’t you?”
Nope, that’s not true either.
We all believe these kinds of myths because they're perpetuated in movies
and television shows and sometimes even in YouTube videos that you've watched.
But we need to make sure that we dispense with these myths,
that people who need to detect deception for a living
really know the truth and understand how to do it,
so that we can all be safer and live better lives.
Today, I’m going to tell you about three facts about deception,
and I'm also going to talk about some solutions,
some ways that we can really detect deception without relying on these myths.
The first fact is that humans are terrible lie detectors.
We are wrong about half the time if we’re trying to judge between truths and lies.
That's because we're full of biases.
We have experiences and history that color the way that we perceive things,
and we often believe some of the myths
because we don’t always get good feedback on our decisions.
We also look for the wrong cues.
Many of you might believe that the eyes are the windows to the soul,
that you can really tell when people are lying by looking them in the eye,
and that’s simply not true.
Liars can lie while they look you in the eye.
In fact, some of you may have done it already,
but you really need to not rely on those myths
and misperceptions about deception if you want to detect it accurately.
The second fact I want to talk about is that there is no Pinocchio’s nose.
We would all like one or two cues
that we could look for and always detect deception,
and I’m sorry to tell you that just doesn’t exist.
There’s a company that works with law enforcement
that says they can detect deception just by looking at blinks of the eye,
or sometimes they’ll say it’s the twitches in the face
or the diameter of your pupils.
If anyone tells you that they can detect deception
using one or two quick tricks like that, they simply aren’t telling you the truth.
And there is no one tell that works for everyone.
The third fact is that deception is subtle.
It’s beneath the surface.
It is very small differences between truth and lies that we’re looking for.
And so we might tell a true story,
but just alter one fact, like the day it happened,
or you might tell a story and leave out some important details.
So lies and truths are embedded together,
and it makes it more difficult for us to detect them.
So what do we do?
How do we detect deception, then,
if it’s so difficult and there are no good cues for us to use?
Well, the first thing is to stop using just one cue.
If you think you’re looking at someone biting their lip
or looking at their eyes, then that’s not going to do it for you.
Instead, what I tell people is to look for clusters of cues,
to look for patterns of behavior that might reveal deception,
and the things that I like to look for
are uncertainty, tension, and cognitive load.
So let’s talk a little bit about what those things look like.
The first cluster that I like to talk about is uncertainty,
because when people are telling a lie, they often are making something up.
They’re not talking about their lived experiences,
and they don't have memories to draw from that they can use to tell the lie.
This means when they’re telling their story,
they’re more ambivalent and they don’t have as much detail in their story.
It might be more implausible, like it doesn’t sound like it could really happen,
and when they’re gesturing or using their body, they’re not as involved,
they’re less animated, and they use fewer first-person pronouns
because they aren't really owning the story.
All those things add up to something
that makes someone look a little bit more uncertain
when they’re lying than when they’re telling the truth.
The second cluster is around tension.
Tension is the opposite of relaxation,
and innocent people can be tense, too, if you’re questioning them
and they’re afraid you’re not believing them,
but liars are often tense because they’re being extra vigilant.
They’re watching you, making sure that you’re believing them,
and trying to adapt to what you’re saying.
And this comes out in lots of different ways:
They might have an increased pitch of their voice.
They might purse their lips, press them together.
They might have fewer smiles, less facial animation, and they might gesture less.
They sometimes freeze up and they don’t gesture naturally
like we do when we’re talking.
The third cluster is around what I call cognitive load,
and cognitive load is what happens when your brain is working extra hard,
and liars are working extra hard
because they’re trying to keep their story straight,
they’re monitoring you,
they’re making sure that they’re believed, and they’re trying not to be inconsistent.
And so when you're looking for cognitive load,
you might notice inconsistencies or contradictions in what they’re saying.
They might give very short answers, and they might repeat themselves more -
use the same story, the same exact words even, over and over again,
and they might pause for longer periods of time
while thinking of what they’re going to say next.
It’s basically a sign that their brain’s working overtime.
Notice that all three of my clusters
are combinations of verbal and non-verbal cues.
You can’t just look at someone and expect to see it;
you have to also listen to what they’re saying
because the linguistic content, the verbal cues,
are just as important as the nonverbal cues.
We don’t shout “Liar” when we see someone press their lips together.
You have to look at the whole picture
and try and get a sense of what they’re doing overall.
When you do see signs of these clusters,
it doesn’t automatically mean that they’re lying,
but it means you should probe for more information,
or you can check out their story and make sure that it’s really accurate.
Back to my suggestions.
My third suggestion is that we shouldn’t rely on flawed humans by themselves.
Computer algorithms can help us to detect deception
because they can look at all of these different cues
in ways that humans simply can’t process all at once.
That would be hard to do in conversation,
but it is something that law enforcement
and other agencies could be doing right now.
In my lab, we use facial tracking,
gesture tracking, pupillometry, even thermal imaging
to try and get at a host of different non-verbal cues at once
and verbal cues as well.
We track posture, gestures, vocal tone, linguistic content,
literally hundreds or perhaps even thousands of cues at one time.
Now, when I say to people that I work with computer algorithms
to detect deception, they start getting scared.
They start thinking of “The Matrix” or “The Terminator” or “Minority Report”
where computers take over human decision-making and run amok.
But I’m not talking about turning decisions over to AI;
I’m talking about using the computers that we have now
to detect deception more accurately.
It’ll be less biased, more objective, and it’ll help humans do things
that we’ve proven humans can’t really do on their own.
So I hope from this talk,
you’ve learned some ways to think about deception a little bit differently
and some ways to perhaps detect deception more accurately in the future.
Thanks.
(Applause)