In this video excerpt from NOVA scienceNOW, learn how a person’s brain activity can reveal when he or she is lying. Correspondent and New York Times technology columnist David Pogue explores how deception can be identified from images of brain waves. Scientist Jennifer Vendemia uses electrodes placed on the scalp to measure electrical impulses from brain cells while a test subject lies and tells the truth about different statements. When a person lies, it takes longer to process the information than when he or she is telling the truth and a type of brain wave (P300) is often missing from the images of brain activity.