Symposium: 'Will brain imaging be lie detector test of the future?'

For almost a century, one of the staples of crime stories has been the wires, cuffs, and jiggling recording needle of the polygraph machine. In its time, the "lie detector" was hailed as a way to measure the telltale physiological signs of deception, including hard breathing, high blood pressure, and excess perspiration.

But in truth, the polygraph was never very accurate, hitting the mark only about 85 percent of the time - and meanwhile creating a lot of "false positives." As many as 25 percent of people telling the truth during a polygraph exam come out looking like liars.

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