London: A new test that monitors a person's full-body movements for signs of guilt can identify liars with over 70 per cent accuracy, scientists say.
The test, developed by an international team of researchers, is based on the premise that people fidget more when they lie.
The research, led by former Lancaster University PhD student and Cambridge researcher Dr Sophie van der Zee, used an all-body motion capture suit - the kind used in films to create computer-generated characters.
The suit contains 17 sensors that register movement up to 120 times per second in three dimensions.
The researchers using the suit were able to identify liars with over 70 per cent accuracy.
"This method is effective because of its sensitivity to subtle changes in behaviour that are difficult for human judges to detect," said Professor Paul Taylor of Security Lancaster, who worked on the research.
"Combine this robust measurement with effective questioning techniques, and the accuracy of this approach may improve still further," Taylor said.
The experiment carried out by Van der Zee, Taylor, and their colleagues Ross Anderson of Cambridge University and Ronald Poppe of Utrecht University, involved 180 participants at Lancaster University lying and telling the truth about two experiences.
The research suggests motion capture may be at least 10 per cent more accurate than the polygraph, which is widely used in the US for criminal cases.
The polygraph's reliance on anxiety-based physiological responses is problematic, because being strapped to a machine whilst being interviewed by a police officer can cause anxiety regardless of guilt.
The new detector identifies changes in body movements related to feelings of guilt rather than anxiety.