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New technology detects a lie before it's spoken

A peek at a brain can unmask a liar

Sunday, May 25, 2003

By Joann Loviglio, The Associated Press

PHILADELPHIA -- Scientists are turning to cutting-edge technology, from MRIs to near-infrared brain scans, in an attempt to answer what courts and corporations have long wanted to know: How can you prove that someone's lying?

But as research presses on, critics say, there's another question that must be addressed: Is it ethical to look into people's minds if they're suspected of being untruthful, even if uncovering the lie would benefit the greater good?

At the University of Pennsylvania, biophysicist Britton Chance is testing a headband outfitted with near-infrared light emitters and detectors to "see" blood-flow changes in the brain, and psychologist Daniel Langleben is putting volunteers inside a type of MRI and telling them to lie as the machine photographs their brains.

Both say their work could potentially be used to detect deceit more accurately than today's polygraphs, a prospect that not everyone appreciates.

"There's only one thing worse than a lie detector that doesn't work, and that's a lie detector that does work," said physicist Robert Park, a longtime polygraph critic. "It's the last invasion of privacy that you can imagine, and it frightens me that we seem to be almost able to do it."

Chance said his brain-imaging machine "penetrates the skin and the skull into the prefrontal cortex, where social inhibitions reside, where decisions are made and which is stimulated by deceit."

Subjects are asked to answer some questions truthfully and others not, and the tiny bursts of brain changes, only milliseconds long, are read by the sensors and fed into a computer. The changes begin when the subject makes the decision to lie, before the lie is spoken, Chance said.

He says his machine theoretically could evolve so the headband itself isn't needed.

"We're interested in covert detection of prefrontal activity, where the subject may not be told the experience is occurring. That's in the future but it is possible," he said. "Obviously, there are ethical problems."

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 -- and largely unreliable, as evidenced by people such as former CIA agent Aldrich Ames, who passed polygraphs, concealing his work as a Russian spy.

Though federal agencies use polygraph tests to screen workers and job applicants, courts do not allow them to be admitted as evidence. Researchers believe the new wave of machines could change that.

"I doubt that anything in life will ever be 100 percent reliable, including lie detection. But will we have a technique that's good enough to be taken as one source of evidence? Probably," said Stephen Kosslyn, a Harvard University psychology professor who is studying the brain scans of liars.

"It strikes me as odd that people seem rarely to see the positive side of a reliable lie detector," he said. "If you're innocent, wouldn't it be nice to have a way to support your claims?"

Langleben is using functional magnetic resonance imaging, which detects part of the brain active in response to specific stimuli. Volunteers were given a specific playing card and told to not divulge it. They were then placed within an MRI scanner and "interrogated" by a computer, which showed them a series of cards and asked them whether they had that card.

When each volunteer lied, part of their brain lighted up, Langleben said.

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.

The machine has already been used in an Iowa court by a convicted murderer petitioning for a new trial. The test showed that the defendant, Terry Harrington, had no memory of the crime scene, but the judge refused to accept it as evidence.

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

But if it does, "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," he said.

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