The full-body suit that can tell if you're lying: Polygraph monitors fidgeting suspects' movement up to 120 times a second for signs of guilt

  • New lie detector test that puts suspects into a full-body suit developed 
  • Suit polygraph better at spotting signs of guilt such as fidgety movements
  • £30,000 suit contains 17 sensors detecting movement 120 times a second
  • Detector is far more reliable than previous polygraphs, researchers say

By DAILY MAIL REPORTER and OLLIE GILLMAN FOR MAILONLINE

Published: | Updated:

A new lie-detector test has been developed that puts suspects into a full-body suit for questioning.

Interrogators have long used polygraphs to detect untruths, but the reliability of the technique has always been doubted.

Now researchers in Britain and the Netherlands have developed a test which they claim has a success rate of more than 70 per cent. The team say traditional polygraphs are only 60 per cent accurate.

Interrogators have long used polygraphs to detect untruths, but a new full-body suit is said to be more reliable than previous lie detectors (archive picture)

Interrogators have long used polygraphs to detect untruths, but a new full-body suit is said to be more reliable than previous lie detectors (archive picture)

The new method monitors a suspect’s full-body movements for signs of guilt because liars tend to fidget more, The Guardian reported last night.

The suit, which contains 17 sensors that detect movement up to 120 times a second, costs £30,000 but the scientists are looking at cheaper ways of replicating their creation.

Researcher Ross Anderson, professor of security engineering at Cambridge University, said: 'The polygraph has been around since the 1920s and by measuring physiological stress induced by anxiety you can get to 60 [per cent accuracy]. 

'However, it can easily be abused as an interrogation prop and many people are anxious anyway facing a polygraph on which their job or liberty depends.

'The takeaway message is that guilty people fidget more and we can measure this robustly.'  

Findings from the  study, by academics at Cambridge, Lancaster and Utrecht universities, will be published today at an international science conference in Hawaii. 

The researchers' experiment involved 180 students at Lancaster University. Half were told to tell the truth and half were told to lie.

The full-body suit was put to the test as the test subjects were quizzed on a computer game, which some had played and some had only read notes about.

The new suit monitors a suspect’s full-body movements for signs of guilt because liars tend to fidget more (file picture) 

The new suit monitors a suspect’s full-body movements for signs of guilt because liars tend to fidget more (file picture) 

A second experiment saw some of the students hand a wallet in to a lost property box while others hid it. Both groups were then questioned while wearing the suit.

'Overall, we correctly classified 82.2 per cent of the interviewees as either being truthful or deceptive based on the combined movement in their individual limbs,' the report says.

The suit correctly identified people telling the truth 88.9 per cent of the time and liars on slightly more than three-quarters of occasions.  

Mr Anderson said: 'Our first attempt looked at the extent to which different body parts and body signals indicated deception. It turned out that liars wave their arms more, but again this is only at the 60 per cent level that you can get from a conventional polygraph.

'The paydirt was when we considered total body motion. That turns out to tell truth from lies over 70 per cent of the time, and we believe it can be improved still further by combining it with optimal questioning techniques.'

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