How accurate is the new "emotion detector" which claims to see when someone is lying?

A sophisticated new camera system can detect lies just by watching our faces as we talk, experts say.

The computerized system uses a simple video camera, a high-resolution thermal imaging sensor and a suite of algorithms.

Researchers say the system could be a powerful aid to security services.

It successfully discriminates between truth and lies in about two-thirds of cases, said lead researcher Professor Hassan Ugail from Bradford University.

The system, developed by a team from the universities of Bradford and Aberystwyth in conjunction with the UK Border Agency, was unveiled today at the British Science Festival in Bradford.

This new approach builds on years of research into how we all unconsciously, involuntarily reveal our emotions in subtle changes of expression and the flow of blood to our skin.

We give our emotions away in our eye movements, dilated pupils, biting or pressing together our lips, wrinkling our noses, breathing heavily, swallowing, blinking and facial asymmetry. And these are just the visible signs seen by the camera.

Even swelling blood vessels around our eyes betray us, and the thermal sensor spots them too.
http://www.bbc.co.uk/news/science-environment-14900800

In a related article: Terrorist 'pre-crime' detector field tested in United States:

Future Attribute Screening Technology (FAST), a US Department of Homeland Security (DHS) programme designed to spot people who are intending to commit a terrorist act, has in the past few months completed its first round of field tests at an undisclosed location in the northeast, Nature has learned.

In lab tests, the DHS has claimed accuracy rates of around 70%, but it remains unclear whether the system will perform better or worse in field trials. "The results are still being analysed, so we cannot yet comment on performance," says John Verrico, a spokesman for the DHS. "Since this is an ongoing scientific study, tests will continue throughout coming months."

Some scientists question whether there really are unique signatures for 'malintent' — the agency's term for the intention to cause harm — that can be differentiated from the normal anxieties of travel. "Even having an iris scan or fingerprint read at immigration is enough to raise the heart rate of most legitimate travellers," says Ormerod.

http://www.nature.com/news/2011/110527/full/news.2011.323.html