Savvy liars can fool polygraph tests by keeping their cool—witness double agent Aldrich Ames. But they may meet their match in a new lie detector developed by Britton Chance, a physiologist at the University of Pennsylvania. Although some people are adept at consciously controlling their pulse and blood pressure, Chance's detector uses near-infrared light to sense minute blood-flow and metabolic changes in the brain, which are almost impossible to manipulate.
To zero in on which blood-flow bursts indicate lying, Chance and his team told subjects to answer a series of questions deceptively and then recorded the vascular changes in the prefrontal cortex, the brain's decision-making center. Some civil-liberties advocates are already decrying the headband lie detector as one more step toward a surveillance society. Chance counters that he expects his invention to be used for homeland security rather than criminal investigations but acknowledges that "this device could have definite social consequences."