You don’t need a polygraph to determine whether or not someone is lying to you. Professionals that conduct interrogations are trained to spot a liar without the help of machines. It’s important to note that many signs of lying are consistent with nervousness and anxiety, which may or may not be related to telling the lie. To determine whether or not he’s lying, look for more than just one clue.
Listen to His Voice and Watch His Mouth
You may be able to determine if a person is lying by the sound of his voice. His voice may become higher in pitch than usual, according to Mary Ann Campbell, an assistant professor of psychology at the University of New Brunswick in a ReadersDigest.ca article. His voice could also crack under pressure. Further, a big lie can cause the body’s autonomic nervous system to release adrenaline, which causes a dry mouth, according to psychiatrist Alan Hirsch. Look to see if the person is doing things that indicate he’s dry in the mouth area, such as licking his lips or clearing his throat.
Look at His Eyes
A person who is lying may give away his deceit by avoiding eye contact with you, according to former CIA officer Lindsay Moran in a 2010 Forbes.com article. However, if the person is a psychopath, he will be able to make direct eye contact while lying because of his lack of remorse. Keep in mind that in some Eastern cultures, keeping eye contact is considered rude, so take his culture into consideration. If you do get a chance to look into his eyes, focus on his pupils. If they are dilated, this is a sign of stress and may signify that he is lying.
Pay Attention to Pauses
If you notice he takes longer to respond, this could contribute to evidence that he may be lying. In a study published in the March 2013 issue of the journal "PLOS One," the researchers found that people who are lying need more time to formulate a response than those who are telling the truth. In between pauses, a liar may increase the amount of “ums” and stutters to fill in for the extra time he needs to think.
Interrogators are trained to repeat questions to catch a suspect in a lie. Pay attention to the initial response and any inconsistencies in his answers that follow. This is a good way to catch a liar, but if he’s really good at deceiving, he will most likely be on top of the details. To trip him up, try to ask a number of follow-up questions, immediately following each main question. Putting him on the spot will make it harder for him to support the lie, suggests Kang Lee, psychology professor at the University of Toronto, whose main focus of research is lying in adults and children.