If your husband comes late at your anniversary dinner and starts giving you an intricate, blow-by-blow rundown of what exactly held him up, then beware - he is probably lying, at least according to a researcher.
Sharon Leal, a research fellow at the University of Portsmouth, who is into insurance fraud, said that liars give themselves away by thinking too hard about their story and tend to overelaborate.
Leal examines how people behave when they make fraudulent insurance claims. She said that her research has shown 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 is these changes, which are most likely to form the basis of new investigative methods designed to spot the cheats.
"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," the Daily Mail quoted Leal as saying.
Leal said that many current techniques and lie-detector gadgets are 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," she said.
"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," she added.