Heat-Detecting Sensor May be Able to Detect Lying

By Bijal P. Trivedi
National Geographic Today
January 2, 2002

As if taking off your shoes at the airport and having them electronically sniffed for explosives was not strange enough, future security devices could include heat sensors that would scan crowds for individuals thinking about committing, or having committed, some sort of deceptive act.

A new sensor has been developed based on the finding that lying or other acts of deception tend to cause excessive blood-flow to the face that can be detected with thermal imaging equipment. According to a new report published in the January 3 issue of the journal Nature, lying triggers a rush of blood around the eyes that can be detected by the heat sensor.

The expectation is that such technology might ultimately be used to pluck out terrorists or other criminals from crowds.

The researchers, led by James Levine, of the Mayo Clinic in Rochester, Minnesota, tested the heat-sensing lie detector by having some test subjects commit a mock crime—in this case stabbing a mannequin and taking its money. The subjects were then asked if they stole U.S. $20.

Levine found that the imaging device correctly pegged 83 percent of the study subjects as either innocent or guilty.

"If after more testing the technology proves accurate it could prove invaluable in high-level security operations, such as airport security, border checkpoints, schools, and federal buildings," said Levine.

Levine began working on the heat-sensing lie detector quite serendipitously.

Levine's research at the Mayo Clinic focuses on how subtle activities alter a person's metabolism. One such activity that piqued his interest was gum-chewing.

A few years ago Levine found that gum-chewing increased metabolism by 20 percent. To determine which muscles where involved in this task he had volunteers chew gum in the dark next to a thermal-imaging camera. One day during these dark gum-chewing sessions a metal plate fell in the room creating a loud crash.

The startling noise caused the panicked gum-chewer's face to glow on the thermal-imaging camera as blood rushed to her face.

This was the "Eureka moment," said Levine. "We wondered whether anxious behavior always caused blood to rush to this area around the eyes and wondered whether a thermal-imaging camera could be used as a lie detector."

The thermal-imaging technology is about as accurate as a polygraph lie detector, which measures pulse, blood pressure, breathing, and sweatiness. But the difference is that only when an expert administers the polygraph is accuracy more than 80 percent, said Levine.

Continued on Next Page >>


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