why context is key when it comes to uncovering liars

Warning: includes spoilers for episode one of The Traitors.

The Traitors has returned to BBC One with a second season after the runaway success of the reality show’s debut series.

In the game show, 22 strangers stay at a remote castle and compete in a number of challenges to win a prize fund of £120,000. A small number of players are secretly selected as the “traitors”.

The remaining players, known as the “faithfuls”, have to root out the traitors if they are to take home the cash prize. They must do this before the traitors “murder” them – sending them out of the competition overnight.

Fellow faithfuls do not know who has been “murdered” until the unlucky player does not arrive for breakfast in the castle the next morning. The traitors must lie about their identity and appear as a faithful if they want to win.

The faithfuls seem to find it difficult to uncover the traitors’ true identities, whether that is at the round table, where the players discuss who they think are traitors, or as the traitors enter the breakfast room the morning after a “murder”. The faithful seem unable to tell lies from truth.

Research has found that people are only marginally more accurate than chance at judging whether someone is lying or telling the truth.

One reason we are such poor lie detectors may be because we tend to believe others are telling the truth more often than we think that others may be lying to us. This is called the “truth bias”: that is, a bias towards believing what others say.

People are not always truth biased, though. For example, police officers making judgments of strangers show a bias to think that suspects are lying. But when they are making judgments of strangers in contexts unrelated to their job, they become truth biased.

And while those of us who are not police officers are ordinarily truth biased, when we believe we are in a situation where more people have lied than told the truth, we become lie biased too. So, whether we tend towards guessing others are lying or telling the truth depends on the situation.

The Traitors and the problem of context

The Adaptive Lie Detector account (Alied), a theory of how people decide who is lying, offers an explanation for these findings. It claims that when people make judgments about a particular statement (such as “I was in Wales last week”), they try to use reliable information about that statement to decide if it’s true or not.

For example, CCTV footage confirming the claim would be reliable information that the person is telling the truth. A witness contradicting the claim would be reliable information that they are lying.

Alied says that when reliable information is not available, people instead use their understanding of the situation to make a judgment. If most people in this situation usually tell the truth, Alied claims that people will usually believe others. If most people in this situation lie, Alied claims people will usually disbelieve others. Research in my own lab and in other labs has supported Alied’s claims.

In The Traitors, there is very little reliable information available to the faithful. There is no CCTV footage of the traitors meeting. The traitors do not personally deliver the murder note. There are no reliable pieces of information that the faithful could discover. They have little to work from other than their observations of people’s behaviour.

And while some of the players in the new series have mentioned plans to look out for eye contact and watch people’s faces, research shows that nonverbal behaviour is not a reliable indicator of deception.

According to Alied, when there is no reliable information, people rely on their understanding of the situation. The situation in The Traitors, known to all the players, is that there are many more faithful players than traitors. And so, while suspicions may run wild, most people are being honest in this situation.

Alied would predict that contestants on The Traitors will believe most others around the round table. And while we are seeing lots of the faithful accusing others, each individual faithful player tends to accuse only a small number of people, often only one person. If Alied is correct, the faithful are continuing to believe most of the others around them.

Spotting liars is a difficult task. But the traitors still run the risk of presenting behaviours that the faithful may interpret as deceptive. To quote Harry, one of the traitors of the new season: “If you can’t be good, be careful”.

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