The television show The Traitors, which returns to RTÉ One this evening, shows just how good some people are at telling lies, and how bad most of us are at spotting deception.
So why is it so difficult to catch a liar?
Speaking to RTÉ's This Week, Dr Gillian Murphy a senior lecturer in the School of Applied Psychology in UCC said we are primed to be interested in lying, to want to understand it, and get better at lie detection.
"There's a real evolutionary basis to that," she says.
"We've evolved in a different way to lots of other species in that we're very social animals.
"And if we're going to work as a society and we're going to trust each other and we're going to share tasks and share resources, then people being able to lie is such a threat to us."
So is it difficult to be a good liar? Dr Murphy says that depends on how complicated the lie is, and the stage we are at in life.
"Children tend to be very transparent when they’re lying, it’s very obvious," she says.
"We get better at it as we get older, but there's a multitude of factors that will make certain lies maybe more difficult to sustain or more difficult to make them believe."
A lot, she says, depends on how much of a ruse you're trying to build. How complex the lie is, and how much capacity we have, as liars to sustain the deception.
"Within psychology, we would talk about the cognitive effort of telling a lie," she says.
"And a lot of theories around deception really relate to that idea that you don't have an unlimited brain capacity, you don't have an unlimited span of attention.
"And if you are constantly trying to think, what would I say if this were true, and you're trying to build a very complex fake world, that requires a lot of effort."
She says a lot of our strategies for trying to detect deception rely on trying to max out that effort "trying to trip people up, trying to take advantage of the fact that actually constructing a lie and telling one can be very difficult when you're trying to monitor what you're saying."
Asked whether people have "tells" - do they change their body language, do they shift their gaze when they are telling lies, Dr Murphy said there is decades of research on this, but no singular reliable sign of deception.
People not good at detecting a liar by looking for signs
People, she says, are not very good at detecting a liar just by looking for tell tale signs, or changes in body language.
"The signs are too faint and too unreliable," she said.
"We really just can't rely on them at all. And so when someone tries to detect [a liar] just paying attention, they'll really only succeed at a bad chance level.
"So, you know, they'll be right about 50% of the time. And even people who think they might be particularly good at it, often they're not."
Dr Murphy said it is slightly different when the liar is someone you know because then you have a sense of them, and know what they look like when they’re lying versus when they’re telling the truth.
So why are people often quite good at lying? She says the answer is very straightforward: "We evolved to be able to lie."
There are advantages to being able to lie, there is a reason why we are good at it, and if we all behaved in a certain way when we lie, then it would defeat the purpose of being able to lie.
So how do you catch a liar? The writer Mark Twain once wrote that if you tell the truth you don’t have to remember anything.
Dr Murphy agrees: "A good way to kind of trip up a liar is to put more effort on them. Make them go into more detail."
She agrees that it is a life skill to be able to catch a liar. Every day there are people who are trying to deceive us, whether it be purveyors of fake news or someone trying to con us out of our hard earned money. It is important to have some skills to spot people who are being deceptive.
Dr Murphy said sometimes you just get a bad feeling about a liar: "If you look at people who are good at spotting a grifter, often they'll have a very intuitive, immediate response that says…you know, this guy is fishy.
"I think he's smarmy, he's lying, and I'm not sure why."
But she also points out that not all lying is bad.
"We tell white lies all the time. Even just putting on kind of a face, anyone who works in customer service will know they engage in what we would call the emotional labour of having to put on a cheerful face and say, 'oh, I'm having a great day' when you're not.
"That's also a form of lying."
"It's a really broad spectrum and we tend to focus on the negative aspects of lying, but there are lots of positives too and we sometimes do it to actually preserve our relationships."
