"Move your eyes, blink, smile. Now try to relax," she says. "We will see if you ____(I)____ a good or bad liar shortly."

Prof Hanein and colleague Prof Dino Levy lead a team at Israel's Tel Aviv University that have developed a new method of lie detection.

They say they have identified two types of liars - those who involuntarily move their eyebrows when they tell a fib, and those that cannot control a very slight lip movement where their lips meet their cheeks.

Their software and its algorithm can now detect 73% of lies and they intend to improve that as they develop the system. "When you try to conceal a lie, one of the things you try to avoid is any sort of body reaction," she says.

Prof Levy adds: "But it's very, very hard for you to conceal a lie with this technology."

Methods of lie detection have probably been around for as long as tall tales have been told. One of the first documented examples comes from 1000BC in China, where a suspect would have to fill his or her mouth with dry rice.

After a period of time the grains would be checked, and if they remained dry then the person was determined to be guilty. The theory was that if the individual had indeed lied he or she ____(II)_____ fearful or nervous, and therefore have a dry mouth.

The early 20th Century saw the invention of the first lie detection machines or polygraphs. The most well-known of these is the "analogue polygraph", which typically has three or four ink-filled needles that dance round on a strip of moving paper.

The suspect has sensors attached to their fingers, arms and body and the machine then measures breathing rate, pulse, blood pressure and perspiration as they answer a series of questions.

Yet there are continuing concerns about the accuracy of these machines and whether it is possible to fool them. So researchers and technology firms around the world are working to develop more high-tech polygraph systems.

[…]

It is important to stress, however, that the legality of lie detectors varies greatly from country to country.

In the UK, polygraphs have been used by the probation service "in the management of people convicted of sexual offences" since 2014. And they are now being trialled regarding domestic abuse offenders.

But the results of polygraph tests cannot be used in criminal cases in the UK's three separate legal systems - England and Wales, Scotland and Northern Ireland.

At the same time, UK employers are allowed to offer a lie detection test to staff, but this has to be optional.

In the US, the rules differ from state to state, with the further complication of US-wide federal law on top.

https://www.bbc.com/news/business-60153129

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