Lying generates unique brain activity that can be measured by functional magnetic resonance imaging (fMRIs), brain scans that could someday morph into a forensic tool far more potent than the flawed polygraph test.
Researchers gave 18 subjects a playing card, then offered them money to lie to a computer about the card while undergoing an fMRI. When subjects lied, the scans revealed increased activity in several regions of the brain, including the anterior cingulate gyrus, which is implicated in conflict monitoring, attention and response inhibition. Head researcher Daniel Langleben, M.D., a professor of psychiatry at the University of Pennsylvania, says this confirms that the brain's "default" response is to tell the truth. "No area of the brain works harder to tell the truth than to lie" says Langleben.