Scientists seek to say 'I can see you lying'

PHILADELPHIA - In the quest to build a better lie detector, scientists are seeking to go beyond the body's indirect signals to the very seat of deceit: the brain.

One researcher has built a headband outfitted with lights and detectors able to "see" blood-flow changes in the brain. Another uses magnetic resonance imaging to snap several split-second pictures.

Britton Chance, a biophysicist at the University of Pennsylvania, leads the headband project, which uses near-infrared light to peek at the brain's prefrontal cortex, the place where people make decisions - and where lies are born.

Research subjects wearing the headband are told to answer some questions truthfully and others deceptively.

At the moment a subject makes the decision to lie, before even uttering it, there's a milliseconds-long burst of blood flow. Those bursts are read by the sensors and show up as spikes on a laptop computer.

Traditional lie detectors, known as polygraphs, measure heart and respiratory rates as a person answers questions. Critics claim polygraphs are easy to beat: They say something as simple as stepping on a tack placed in a shoe can skew results in the test-takers' favor. Researchers believe the technologies they're working on could change that - though it could take several decades to get it right.

As Chance develops his headband, another Penn researcher, psychologist Daniel Langleben, is putting volunteers inside a type of magnetic resonance imaging machine and telling them to lie as it photographs their brains.

Langleben's MRI detects which part of the brain is active in response to specific stimuli. Volunteers were told not to divulge a playing card they were given. They were then placed within an MRI scanner and "interrogated" by a computer. When volunteers lied, Langleben said, part of their brains lit up.

Chance and Langleben contend that people can't change what happens in their brains during a lie, so a machine accurately measuring those changes would be next to impossible to beat. Polygraphs, on the other hand, essentially measure the fear of getting caught lying, symptoms that can be beaten.

Other scientists are looking at "thermal imaging" (training a heat-sensitive camera on people's faces that would register increased blood flow around the eyes) and "automated face analysis" (a computer that analyzes the tiniest expressions in the face) as potential lie detectors.

Lawrence Farwell, an Iowa-based neuroscientist who runs Brain Wave Science Inc., has developed what he calls "brain fingerprinting." It focuses on a specific electrical brain wave, called a P300, which activates when a person sees a familiar object.

Barry Steinhardt, director of the American Civil Liberties Union's technology and liberty program, warns that none of the new technology has been proven to work like the scientists claim.

But if it does, Steinhardt said, "then it would become another weapon in the arsenal of those who want to put us into a surveillance society where every action, every deed and one's very thoughts can be monitored, categorized and correlated."

© 2006 • All Rights Reserved • St. Petersburg Times
490 First Avenue South • St. Petersburg, FL 33701 • 727-893-8111

Contact the Times | Privacy Policy
Standard of Accuracy | Terms, Conditions & Copyright