Trying to spot when someone is lying is not easy. For a start, the common belief that liars avert their gaze when they’re telling fibs is not true. Most of the time, they’ll be looking straight at you.

A much more reliable way of detecting someone is telling you a lie is to concentrate on the amount of detail they’re sharing with you. It’s always been believed that details were an easy indicator of honesty, but this is not the case.

Researchers from Maastricht University, Tilburg University, and led by Bruno Verschuere, associate Professor of Forensic Psychology at the University of Amsterdam conducted nine separate tests on more than 1,000 people to examine their lie-spotting abilities, and they discovered that people are able to spot lies more easily when examining one piece of the narrative than the whole story.

It might feel counterintuitive to listen to what people are saying without paying attention to all kinds of other signals, such as how convincingly or emotionally someone conveys their story. If they include a lot of detail in their story, or seem to get emotional, that’s a signal they’re lying through their teeth.

People who are telling the truth can give a rich description because they actually experienced the event, but although liars can invent details, this actually increases the risk of getting caught out.

Tests conducted by the researchers included showing participants videos, statements, transcripts and live accounts of an event. In the first test, 39 participants were faced with statements describing the recent activities of students that were both true and invented. These involved accounts describing walking around the campus, their activities, who they met or what they did — and also details of their thought processes.

Having examined all the accounts, each participant was then asked to rate each statement on a scale from ‘totally deceitful’ (−100) to ‘totally truthful’ (+100), Across the experiments, participants were either instructed to look out for all possible clues of deception or to focus on specific apparent behaviours.

The researchers concluded that relying on just one good cue to detect a lie was much more reliable than trying to pick up on a handful of cues. These could include factors such as location, the person’s behaviour or even the time of the event.

When judging rich statements of a past event, details provided an easily assessed indicator of truth. But despite their diligence, they concluded that detecting deception was “incredibly difficult” as participants had an overall accuracy rate of 59% to 79%.

Some previous research suggested that the approach should vary depending on whom you are speaking with. Friends, colleagues and relatives show different behaviours. Other researchers have pointed to facial expression as an obvious signal of honesty with fake smiles only appearing ‘in the mouth’ and not shown in the eyes.

The reality is that detecting a lie depends on careful observation of the person.

The research was published in Nature Human Behaviour