LYING IN court, to the police or at immigration control looks set to become much more difficult.
Scientists at the universities of Bradford and Aberystwyth have developed a powerful lie-detection system that is non-invasive and can be used without the person knowing they are being assessed.
Initial tests of the system, which uses an ordinary video camera, a thermal imaging system and the power of the computer, showed it can spot the liar about 70 per cent of the time.
Lead researcher Hassan Ugail, professor of visual computing at Bradford, believes accuracy may in time be pushed up to 90 per cent. He describes it as “a completely non-invasive lie- detection technique”.
The polygraph lie detector must be connected to the subject’s body and depends on the person agreeing to submit to the test. Prof Ugail’s device could be used without the person realising they had come under scrutiny.
He described his new system yesterday at the British Science Association’s annual Festival of Science. He believes it is unique given that it involves capturing telltale facial gestures of the subject and also thermal images.
Studies show that lying increases brain activity, which in turn changes the normal temperature patterns seen in blood vessels in the face. The thermal camera can track changes in a blood vessel, watching for a rise in temperature which would indicate the subject was lying.
It can measure changes to as little as 0.1 degree. The video images are streamed back to a computer that tracks subtle changes in the face that could point to a person lying.
These include gestures such as lip biting, slips of the tongue, nose wrinkling, repetitive swallowing and asymmetry or lack of balance in the face. These, along with other less incriminating gestures, are known as “facial action units”.
It is the combination of visual and thermal images that makes the system unique, Prof Ugail said.
Tests showed it could achieve accuracy of about 70 per cent. The subjects were asked to read a story and answer questions either lying or telling the truth. While the system could not always identify which question elicited a lie, it was correct more than two out of three times when the questioning session was combined as a unit.
The system would undergo a field trial at a British airport later this year, overseen by the Home Office, he added.
There is considerable interest given its potential use in counter- terrorism or to provide an assessment of individuals coming through immigration or customs.
It could also be used in a court, by the police when questioning suspects or even as a way to spot facial changes related to diseases such as Parkinson’s. “This is not a 100 per cent foolproof system,” Prof Ugail said. “This would be used as a decision aid.”