University test catches out lie detector cheats

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RESEARCHERS at the University of Portsmouth have created a test to catch out people who trick lie detectors.

The university put together an experiment where 86 people were asked to commit a mock crime by stealing a data file.

Then another 82 ‘innocent’ people were brought into the test who had no knowledge of the ‘crime’.

Both groups of people were subjected to the Symptom Validity Test, which required them to choose one word from a pair of words.

One of the words would always be related to the crime, and the other would not.

Innocent people chose the words at random but liars chose the incriminating words 33 per cent of the time.

People who chose three or fewer crime-related words failed the test.

Failing the test is a strong indication of guilt but researchers warn passing the test does not indicate innocence and it is possible to beat the test using a strategy.

Researcher Dom Shaw said: ‘We found a pattern in the guilty participants’ responses. Our results suggest at some point during the test, some liars worked out that avoiding too many crime-related words would appear suspicious.

‘As a result, they started including more crime-related words to appear as if they were choosing purely by chance.’