Will there ever be a real 'Lie Detector'?

Polygraph Pollyannas

One contender is "Brain Fingerprinting", which claims to use brain waves to measure the familiarity of information: Was someone exposed to this information before, regardless of its emotional salience?  Tiny electrical signals on the scalp (brain waves) evidently reverberate  in a slightly different pattern if you see a familiar vs. an unfamiliar image. Here are two improvements upon polygraphs: the signal comes straight from the brain, rather than from secondary physiological markers, and it claims to deal with more neutral familiarity and "knowledge" of experience rather than the stress of lying abut it (although the information to be tested must be suddenly flashed on a screen for the technique to work).

The inventor and chief promoter, Lawrence Farwell, has sound academic credentials, a handful of refereed publications, a US Senator's testimonial, and has helped reverse a murder conviction. But it will take a far more ambitious research program than his to confirm his methods measure "evidence stored in the brain". Measuring whether this works is at least as hard (and important) as measuring if a heart-drug works, and that kind of research program costs hundreds of millions of dollars.

Mind magnet

An even sexier technology is brain-imaging. In particular, "functional magnetic resonance imaging"- with the subject enclosed by a giant liquid-helium-cooled magnet - is a method for showing not just what your brain looks like, but which parts work harder (leading to colorful brain-pictures with glowing red spots indicating processes like "concentration" or "arousal").

One boffin, Dr. Scott Faro of Philadelphia, has found a handful of regions which seem to glow a bit more when a volunteer is lying then when truth-telling, here. His claims are both more scientific and more circumspect.

"We have just begun to understand the potential of fMRI in studying deceptive behavior," he says.

That caution is encouraging, and not just because a single interrogation costs thousands of dollars in a gadget costing millions. Like any biometric method, lie detection has an uphill fight to bring its false-positive rate low enough to justify its expense and consequences.

But it's also much harder and riskier than other biometrics: you can't verify or refute a lie detection  as easily as a retinal  scan, and you can't measure how well people might game it or react under stress.  And of course, countless careers can be permanently ruined by your mistakes.

The present brand of lie detection still hasn't proved itself scientifically in seventy years of trying, so it should be shelved before it derails even more careers or mistakenly vets even more spies. The new methods may be better, but we should test them as carefully as we do drugs before we give them an equivalent chance to do serious damage. ®

Bill Softky has worked on dozens of science and technology projects, from the deep paradoxes of nerve cells  to automatically debugging Windows source code.  He hopes someday to reverse-engineer the software architecture of mammalian learning, and meanwhile works as Chief Algorithmist at an internet advertising startup.

Sponsored: Go beyond APM with real-time IT operations analytics