I was an FBI agent for 30 years and observed criminals’ behavior when they lied.
I’ve also researched extensively about body language, facial expressions, and verbal indicators of lying. I’ve found that knowing signals that indicate someone is probably lying to you can be helpful to law enforcement officers, teachers, parents, anyone who is wondering about whether to establish or continue a romantic relationship, or anyone who deals with salesmen, repairmen, or contractors, that is, anyone who has contacts or dealings with other people.
I decided to share my knowledge with others, in order to promote more honesty (or less successful lying) in the world. So, I wrote a book titled, How to Spot Lies Like the FBI. In it, I discuss facial expressions, body language, and verbal indicators which likely signal someone is lying to you.
In regard to the facial indicators, you can see that someone is stressed, nervous or lying from observing many signals or “tells.” To eliminate false positives, one should first interact with the person with small talk and by asking general questions. That way you can determine their base or normal behavior. It’s noted that some people show signals that might be connected with lying if they happen to be nervous, jittery or anxious in their normal behavior. And people’s reactions can be affected by allergies, drinking, using certain medications or taking drugs. Also, a small percentage of the population includes pathological liars who will likely feel no stress from lying and probably won’t exhibit the signals of it. And some people will have particular psychological disorders that will change their behavior from the norm. So, watch for the baseline behavior, then look for about three lying indicators that they don’t display regularly, before you conclude they’re lying. With a little practice in making observations, you’ll be quite certain when someone has shown a true lying signal.
Most people react in predictable and observable ways when they lie because they’ll get chemical changes in their bodies, they’ll have physiological responses, and/or they’ll have mental reactions. For instance, a chemical reaction causes peoples’ faces to itch when they lie. If they touch or scratch their nose or cheek or rub their finger under their nose, those are indicators of fibbing. The mouth often goes dry, and you can see their reaction to that when they do a sucking action, usually with pursed lips. They may also lick their lips to alleviate the discomfort. Excess mucus is often produced while lying, so people will either cough several times or clear their throat a few times.
They may chew on or bite their lip. Their eyes may dart from left to right, back and forth, which is an ancient biological reaction when a person faces a dangerous animal or human adversary, and they’re trying to find an escape route. And if they blink several times in a row, faster than the normal blink rate of once every ten or twelve seconds, they’re most likely lying. Also, when you ask someone a question that affects them emotionally, they may show a “microexpression” which shows their true reaction. This only lasts for about 1/25th of a second before they show an expression that they want to display to you, so you have to watch sharply for these instances.
People will often touch or partially cover their mouth with their hand before or after they lie, or they’ll sometimes place a finger beside their mouth during your conversation. Lying people will often perspire more than the conditions call for. You may notice moisture on their foreheads or cheeks, and they’ll sometimes rub the back of their neck because of the discomfort of excess sweat there.
People will sometimes rub a knuckle into their eye socket after lying to you. Their heart rate will increase, their blood pressure will accelerate, and their breathing will quicken. You may notice the pumping of blood in their carotid arteries get faster, they may get short of breath, and their faces and/or cheeks and ears may redden. Also, some people, more likely women, will blush after telling a whopper.
There are other facial indicators and a good many body movements and ways people talk to you that are helpful to know about along these lines. You should probably read a book that discusses facial expressions, body language, and verbal indicators. And I wish you good luck in your future.