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The camera never lies?

12 September 11

Is the 90-year-old lie detecting technology of the polygraph on the way out at last?

This is the hope of Professor Hassan Ugail of the University of Bradford, who is speaking at the British Science Festival on Tuesday. His project, based at Bradford and Aberystwyth universities, is developing a non-invasive lie detection test based on facial images.

He says: “The polygraph uses measures such as skin conductivity and blood pressure, for which we need the subject to comply. But the technology has moved on.” In his project, the subject’s face is recorded by both a normal video camera and a £60,000 thermal imager. The combination should allow lying to be detected with 90 per cent accuracy, comparable to the polygraph, even in unwilling subjects.

The infrared camera detects temperature changes of as little as 0.1 degrees, especially in the skin around the eyes. Because lying involves increased brain activity, blood flow in the face is a key indicator of dishonesty.

The video camera is used to compare the subject’s facial expressions under questioning with their appearance during a series of harmless questions which they will answer truthfully. Professor Ugail says: “We use these questions to establish a baseline condition for the face. Different people have different levels of nervousness. Establishing a baseline allows us to see whether the person is emotional, aroused or nervous. Some of the key indicators are swallowing, lip biting and an increase in facial asymmetry.”

He adds that even this technology cannot reveal whether the answer to a specific question is untrue. It is more likely to become a “decision aid” than an absolute indicator of honesty.

The technology may also have applications beyond law enforcement. “We know that people suffering from Parkinson’s disease have a limited range of facial expression,” says Professor Ugail. “That may mean that the technology can be used to spot the early stages of dementia.” It could also be applied by the marketing industry to gauge customer responses to new products.

The £500,000 project has been supported by the Engineering and Physical Sciences Research Council in collaboration with the Home Office, the UK Border Agency and the technology company Qinetiq.

12 September 11

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