Calling Your Bluff: Brain Scans Reveal the Truth

Nov. 2, 2010— -- We've all done it: a bluff here, a little white lie there. Some people are experts in the art of deception, while others fall flat on their dishonest faces.

It may be difficult to tell if someone is lying from the outside. But a new study is the latest to find that a brain scan may be the ticket to calling someone's bluff.

Researchers from Baylor College of Medicine and California Institute of Technology used functional magnetic resonance imaging, or fMRI, to scan the brain activity of 76 study participants while they played a bargaining game. In the game, a buyer and seller bargained with each other for the best price. Only the buyer knew the real price of the item.

The study authors found that the buyers who bluffed showed more activity in the brain regions that contribute to complex decision-making, maintaining goals, and understanding other people's beliefs.

"Although it's controversial, my interpretation is that humans have a natural instinct toward honesty," said Dr. Colin Camerer, the Robert Kirby professor of Behavioral Economics at California Institute of Technology, and the co-author of the study. "To be actively dishonest requires extra thinking, so the brain would be working harder."

The findings, published in the Proceedings of the National Academy of Sciences, suggest that this brain activity may help differentiate between honest individuals and those who attempt to manipulate their social image in another person's mind. In the future, the authors said these scans could help diagnose mental disorders or contribute to finding the truth in the courtroom.