Ralph Barbieri

Ralph Barbieri administers lie detector tests to guests, who most often are suspected of cheating on their mates. Some guests admit to cheating, refuse to answer one or more of Barbieri's questions or stop the test entirely and confess on video. During the show, Maury reveals the results of the lie detector tests. Barbieri occasionally appears on the show to explain the results, often saying a person had "significant reactions" to one or more questions or he/she "passed with flying colors". Sometimes when reading lie detector results, Maury says "The lie detector determined, Ralph?" and Barberi responds "That was a lie" or "He was telling the truth".

In 2009 a man who had brought his wife to the show 4 years previously cause he doubted he fathered their son and thought his wife was cheating on him. He was the boy's dad and the lie detector test revealed the wife never cheated on her husband. In 2009 the couple returned after 4 years cause the guy still thought his wife was cheating on him and he even thought That Ralph passed his wife because they had sex so the wife took another lie detector test and once again she proved she never cheated on her husband with any other man and she never had sex with Ralph during her 1st lie detector so that he would pass her. Ralph said he would never give anyone a passing grade especially if they offered to have sex with him.

In a 2010 episode, a guest attempted to bribe Barberi by offering $200 to pass him.