Chapter 1: What is the main topic discussed in this episode?
ABC Listen. Podcasts, radio, news, music and more. Tammy Shipley believed someone was out to hurt her. I thought someone was after me and I wanted to just be safe. She's put under 24-hour surveillance.
I tried to get in contact multiple times.
And then something strange happens. She just drank and drank and had something like 20 litres of pure water.
Ambulance emergency. I've got a woman unconscious.
So every now and then, at the start or end of an interview, I will ask the person I'm speaking to how they got interested in their line of work. Sometimes the answers are interesting, sometimes they're not. Rebecca Wilcoxon's answer for how she got into studying lie detection has to be one of the funniest I have ever heard. Especially because the story starts straightforward enough.
When I was younger, my uncle Peter, he worked for ASIO. And he was this really cool guy that spoke multiple languages and looked like a spy. I think that's why I got really interested in forensics. And then it takes a turn. And I once, many years ago, was in a relationship with someone who really lied a lot. So I...
I think that played into it because I once figured out a way to tell if he was lying and it worked for quite a bit.
What was your way? How did you work that out? What was it? What was the method?
So, yeah, he used to lie for just reasons unknown. He was just one of these people that lied a fair bit. Anyway, there was one time he told me some story and I knew it wasn't true. I can't remember what exactly it was, but I had hard evidence that it wasn't true and And I said to him, I know that you're lying because I've figured out a way to tell when you're lying.
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Chapter 2: What inspired Rebecca to study lie detection?
And he goes, oh, is that right? And I said, yes, it is. And he said, well, what is it? I said, you do something with your face. I'm not going to tell you, but you do something with your face when you're lying to me. So for quite some time after that, when every now and then when he's saying something, he'd hold his face really still.
Oh, my God. So you kind of set him up either way.
I did. So that worked for quite some time. Oh, that's so funny.
So were you making it up the first time around when you said it?
Yes, I was. I was making it up. It's just that I had hard evidence. And, yeah, I was just being nasty and said it to him. But then... Yeah, every now and then he'd be telling me something to hold his face really still and go, you're lying.
Rebecca, that is amazing. I'm obsessed with that. All the women of the world and the men of the world can use this now to like catch their partners out.
That's when I knew I wanted to study psychology, I think.
I love it. That's probably the best origin story I've ever heard. So thank you.
You're welcome.
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Chapter 3: What misconceptions do people have about detecting lies?
So yeah, I think in a jury situation, we're up against it. But what people really, really need to do is listen to the evidence.
In Lindy Chamberlain's case, it was four years before new evidence, the discovery of one of Azaria's pieces of clothing near a dingo den, would lead to her acquittal and release from prison, where she'd been serving a life sentence. A final inquest in 2012, 32 years after the original event, confirmed that Azaria Chamberlain died as the result of being attacked or taken by a dingo.
From ABC Radio National, this is All in the Mind. I'm Sana Kadar. Today, it's part four of our four-part series, Forensic, on the psychological tools police use to crack crimes and how they can sometimes fall short. Okay, so if there aren't any solid behavioral ways of telling whether someone is lying or not, what about looking at brain activity?
This is an area that's long been of interest for researchers and law enforcement. The idea that you could scan someone's brain and tell if they're lying or not. But there's a core challenge when it comes to brainwaves and lie detections.
So I can give you a lie detector, let's say, that has 99% accuracy in the lab, but unless I can tell you that we are actually measuring lying with full validity, there is always going to be a way for somebody to cheat that and try to invoke other related processes that we are using in our lie detector to try and seem as if they're not lying when they are.
Arthur Lee is an assistant professor at Boston University in the United States, and he researches complex mental states and how you might decode them using neuroscientific methods. A couple of years back, he and colleagues at the University of Berkeley turned to a puzzle that had plagued science for decades.
Because as Arthur says, there are now ways to detect whether someone is lying with some level of accuracy, at least better than chance, in lab experiments. But those same tests do a very poor job discriminating deception from other emotions or states in the brain, like selfishness or nervousness. That means you can get false positives.
And in the real world, that could translate to false convictions.
So I first wanted to bring up this idea of accuracy versus validity. It's not only important that a test is very accurate, but it also needs to be the case that the test is measuring what it purports to measure. So the question then became for us was, okay, if we use the brain to say, classify when somebody is lying or not, how can we be sure that we are actually measuring lying?
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Chapter 4: How do body language cues mislead us in lie detection?
This is showing that Even though we created what is purportedly a lie detector, the validity of it has shortcomings, and it's actually being confounded with other things like financial interest or selfishness, those kind of things. So this is us saying, if you just focus on improving the accuracy, these are the things you're going to miss.
So if you build a lie detector in the lab, who knows what's going to happen in the real world when there are other things that are confounded with lying.
Oh, and by the way, this is also the broad problem with polygraphs, the lie detectors you see in movies and TV. They're not used in Australia, but some law enforcement in other countries do still use them. Anyways, with their lying data and the selfishness data, Arthur and his colleagues did something interesting.
So then we move on to the third part of the task where, which is, it's not really a task, but essentially we say, we have a way to balance out the signals in the brain such that we can make the confounding signals of selfishness cancel each other out in the brain while retaining most of the predictive power of lie versus non-lie trials.
So this is a bit of a statistical trick that we used to say, we want to build a model that can predict lie versus no lie in the first task as much as possible while staying true to the constraint, the statistical constraint that you should not be able to distinguish selfish versus non-selfish trials at all.
Over simplifying things, if lying and selfishness are two different frequencies, they kind of subtracted the selfishness signal from the lying signal.
That actually works pretty well. You're able to remove this selfishness contrast from the brain while still retaining your ability to detect lie versus non-lie trials. This is not to say that we now have a lie detector.
But this is to say, look, we created a lie detector, we identified a confounding process, and we were able to subtract the confounding process, so hopefully we now have a more purified version of lying, or a mental construct of lying.
If you have other concerns, other things that can be confounded with lying, you can now construct an experiment, subtract those out, and we can keep playing this game until either one of two things happen. One is we remove all confounding process and somehow we're left with this pure lying signature, which means that there is a neural signature that is uniquely tied to lying.
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Chapter 5: What methods are used in lie detection research?
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