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The Traitors - what is the truth when it comes to detecting deception?

As this year’s thrilling season of The Traitors comes to a close this week, a former police officer with a background in psychology and criminology reveals the reality and science of deception detection.

Will Ross really bring down the Traitors from the inside? Will Harry be successful in murdering his fellow contestants? And is there really such a thing as “traitor behaviour”?

According to Jennifer Schmidt-Petersen, Programme and Student Lead for Policing Programmes and Module Lead for Forensic and Criminal Psychology at The University of Law, identifying when someone is concealing the truth really isn’t straightforward. Jennifer says: “Cases such as the one of Karen Matthews show how convincingly some people can lie and how readily they are believed.”

In 2008, Karen Matthews fooled the nation into believing her daughter had gone missing, when she had in fact been knowingly kidnapped by Karen’s then boyfriend in a bid for the pair to split the reward money upon finding the “missing” child.

Jennifer continues: “Research on deception detection has exploded since the mid-90s (Granhag et al. 2018). Especially in crime fiction but also in the real world, there are many claims about fool proof ways to detect deception that work every time and that often involve pseudo-science. In reality, despite some behaviours having found to be associated with lying in some cases, there are no specific cues to reliably help distinguish truth tellers from liars.”

So-called “traitor behaviour” has become the phrase of the season this year, with Ash falling victim early in the series for acting suspiciously. So, can body language really give a Traitor away?

According to Jennifer, body language is not a sure sign that someone is lying: “There are a lot of urban myths about detecting lies and deception. For example, a polygraph is a measure of arousal and not necessarily a measure of lying. Simple signs thought to be indicators of lying can often be misleading, especially in the absence of baseline information for an individual. Cues or indicators of deception that have been identified are just that - indicators. There is no 100% reliable cue that someone is lying. The majority of cues to deceit are actually signs of strong emotion and they can therefore be very misleading.”

With no hard and fast way to tell for certain if someone is lying, it will be down to the discussions at the Roundtable to oust the real Traitors. With that in mind, Jennifer shares three important factors that need to be considered when it comes to deception detection:

1. Understand their baseline behaviour

We’ve seen various discussions from contestants on how people changed from when they first met versus being around the roundtable. While these have mostly led to incorrectly identifying a Traitor, this isn’t a bad strategy to take when it comes to someone we know well. As there is no one cue of deception that is 100% reliable, it has been pointed out that behaviour needs to be compared with what is typical for each individual.

When comparing the baseline with behaviour it may then be easier to detect if the person is struggling to create a convincing account.

2. Use the evidence strategically

Strategic use of evidence is also important. If evidence is disclosed early in an interview, as it sometimes is if the aim is to get a confession, the suspect will have a good idea about what the investigators knows. It may also get a suspect to shut down rather than engage in a dialogue.

On the other hand, the more information is elicited from a suspect before evidence is revealed, the more checkable facts there are. Therefore, a lie can be as useful as an admission for investigators as evidence can help to establish deception if used correctly.

Research also suggests that the perceived strength of incriminating evidence is a key factor when making a decision to confess. Worryingly, the US policing system allows officers to lie to a suspect or exaggerate the evidence they have. For very good reasons, this isn’t allowed in the UK as it can also heighten the risk of an innocent person falsely confessing.

When looking at the literature, it is clear that most people perform well when it comes to telling lies and poorly when it comes to detecting them. This means we need to draw on known facts and evidence to check for truthfulness (Canter and Youngs, 2009).

3. Impose cognitive load

According to psychology, part of an interview strategy may be to magnify possible cues to deception, for example by imposing cognitive load.

Imposing cognitive load essentially means giving the suspect more to think about, perhaps by placing demands on them. In doing so, the ability to process information becomes increasingly complex, which could in turn lead to a slip-up.

Some people may experience keeping a secret as burdensome (Pennbaker, 1989, 1990) and it is also likely to require a lot of cognitive and emotional resources (e.g. Lane & Wegner, 1995).

Jennifer continues: “Watching television programmes and films can be a useful way of learning about police practices or make us feel like we’re a real-life detective. The important thing however is to remember that these programmes are made for our entertainment and won’t always reflect real life. That said, there are plenty of other good reasons why someone may choose a career in policing such as: the opportunity to make an impact in their community, real world relevance, employability prospects, and the intrinsically interesting topic.”

To discover more about topics like this, take a look at our Policing, Criminology and Psychology courses.