How to catch a liar: academic research sheds new light

<span>Portsmouth’s lying and deception research draws on psychology and criminology.</span><span>Photograph: Helen Yates</span>
Portsmouth’s lying and deception research draws on psychology and criminology.Photograph: Helen Yates

Fictional detectives such as Sherlock Holmes or Hercule Poirot – or even Jazatha Christie from The Traitors – can often spot a liar from just a few obscure clues. But in the real world, it’s not as simple.

“A lot of people say they can always tell when someone’s lying,” says Danielle Chandler, 38, who is doing a PhD on the topic of deception at the University of Portsmouth. “But research shows there’s just over a 50% chance of being able to accurately tell, so you might as well flip a coin.”

Chandler says another common misconception is that you can identify a liar from their non-verbal body language. “TV programmes would make you think you can look at someone and tell if they’re lying or not,” she says. “I’ll ask potential students at open days how to tell if someone is lying and nine times out of 10 they’ll say it’s about looking out for behavioural cues, such as that someone doesn’t look at you, or that they fidget a lot.” But Chandler says this can be misleading: “Because if I was in a police interview, guilty or not, I’d probably fidget,” she says. “There are a lot of misconceptions like that.”

The University of Portsmouth is ranked the top university in the world for its lying and deception research, as well as for student recruitment in both psychology and criminology. With good reason – researchers such as Chandler are cutting through the misconceptions and conducting world-leading research that is of interest to practitioners at institutions such as the Home Office, the FBI and the police force.

Their research has practical implications. For example, reviewing deception research, Prof Aldert Vrij, from the department of psychology at the university, and his colleagues, during the Covid-19 pandemic in December 2021, concluded that face masks may actually improve a jury’s ability to spot lies during court proceedings.

Vrij, who is the world’s most prolific author in the field of deception detection, says that non-verbal lie detection techniques, such as analysing body language, are poor ways to tell whether someone is lying. Listening to what people actually say is a far better indicator, he says – though, admittedly, it doesn’t make for entertaining TV.

“We find that lie tellers try to keep the story simple,” Vrij says. “Because they’re afraid to give away leads. Lie telling is more difficult than truth telling, so to make it easier, they give less information. A truth teller’s stories are more complex. So the complexity of stories is often a clue as to whether someone is telling the truth or not.”

Chandler, meanwhile, has been researching the effect of asking someone to draw a sketch during investigative interviews. “Truth tellers tend to include more people in their sketches,” Chandler says. “(Liars are) more likely to draw from a bird’s eye perspective that takes them out of the context. Truth tellers are more likely to draw from an over-the-shoulder perspective, as they’ve actually experienced stuff.”

Research like this can be used by real-life detectives to work out whether someone’s story is reliable. Police work and work carried out by other professional lie detectors is often confidential, says Vrij, however, research produced by the department is of interest to and used by practitioners. “What they do is confidential. So they’re not really telling us exactly how they’re using those techniques. But we do know that they’re interested in it,” he says. The university is collaborating with the Ministry of Defence, the Home Office and US partners. “Our research can be very easily implemented,” he says. “All the research we carry out can be used in different scenarios.”

For example, the department’s research reveals certain interview techniques are helpful for analysing what someone says. “Ask them to elaborate and see what they say,” says Vrij. “You want to encourage them to tell you more. Truth tellers will give you more information. Lie tellers prefer to tell the same story.”

Sometimes in police interviews, officers will have evidence – Vrij’s research has shown that it can be best to keep it hidden from the interviewee. “That’s completely the opposite to what happens in TV programmes,” he says. “What you need to do is to ask about their whereabouts, but don’t reveal the evidence. Truth tellers will be more in alignment with the evidence. If you give all the evidence in advance, (the interviewee) can come up with a story that includes the evidence in an innocent way.”

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Graduates of the university are in high demand when they complete their studies. Some, like Chandler, stay in academia. Others go into practice and work for places such as the Home Office, or the police, Vrij says.

During Chandler’s time at the university, she has had the opportunity to talk to practitioners from across the globe at conferences and events.

“There’s a conference in the summer that’s a mixture of practitioners from all around the world who come to hear about our research,” Chandler says. “There are people from different places like the CIA and the FBI, and from different countries, and they come here. It’s been nice speaking to them and listening to their interview practices and to see how interested they are in our research. Because I think a lot of people are willing to make changes in terms of techniques. As long as we can keep putting this research out and as long as we have this scientific evidence of what we’ve found, then it can be used in practice.”

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