If someone starts explaining why they were late by giving you an intricate, blow-by-blow rundown of what exactly held them up, be warned: that person is probably lying.

A researcher into insurance fraud in the UK said that liars give themselves away by thinking too hard about their story.

Sharon Leal, a research fellow at the University of Portsmouth, examined how people behave when they make fraudulent insurance claims.

The expert in detecting deception said her research showed that liars make extensive plans before they lie, but that truth-tellers do not plan their story.

She explained that because liars need to think about their plan when being questioned, this puts a large load on their brain which in turn affects their behaviour.

She said it was these changes which were likely to form the basis of new investigative methods designed to spot the cheats.

Leal said: “There is a real need to use evidence-based methods that are scientifically proven to work to stop wasting insurance companies’ time and money and to stop innocent people being treated as suspects while the guilty get away.”

She explained that an insurance company’s investigation into a claim could be triggered for a range of reasons, including a large claim on a new policy, or the investigator having a gut feeling that something did not add up.

She said that a common trigger for an investigation was when the claimant could not recall specific details surrounding the incident, such as what the other person was wearing or how many people were in the vicinity at the time.

Leal said: “Insurance fraud has been on the rise since the recession began and insurance companies are very keen to find a way of beating those who cheat.

“There is a saying, ‘Needs must when the devil rides’, which means when times are tough, people are more likely to break the rules. That is certainly true in the case of insurance fraud.

“People think if they are telling the truth it will shine out, but it doesn’t.

“Insurance investigators waste time and money when they chase innocent people.”

Leal said that many current techniques and lie-detector gadgets were unreliable.

“Contrary to popular belief, motivated liars do not fidget, avert their gaze or blink nervously. They are usually calm and have planned their lies down to the last detail.

“Also, many people do not see anything wrong with making a false claim and if they don’t feel nervous or guilty, it follows that the techniques that rely on these factors will ultimately fail.

“Even the majority of experts overestimate their ability to spot a lie. They might as well toss a coin in the air, their record of finding the cheats would be the same at about 50-50.”

Leal has been awarded a grant by an insurance fraud investigation firm to study lying.

She hopes that by studying liars in laboratory conditions she will be able to identify the real clues that give them away when making false insurance claims.

She is spending her first year studying what investigators do and how often their methods are successful and her second year trialling new methods and testing the results. – Daily Mail