You might think that the warning signs of lying are obvious, but some important ones actually are quite subtle or can come off as normal behavior. I called behavioral psychologist Marc Salem, PhD, an expert in nonverbal behavior, and he told me to watch out for these four red flags…

Too much eye contact. This may strike you as counterintuitive—isn’t a lack of eye contact usually a sign of lying, like when someone stares at the ground while addressing you? Dr. Salem says that in most cases, it’s actually the opposite—the liar locks into eye contact with you—and that is because he or she is trying really hard to look truthful. “People naturally look around the room while they’re thinking, so if someone doesn’t do that, it’s a warning sign,” said Dr. Salem.

The leg tip-off. Be on the alert if a new topic of conversation brings about an abrupt change in body language. You probably already know to watch out for someone who suddenly starts sweating…biting his nails…or licking his lips. But there is another classic sign of lying that most people don’t think about—jiggling legs. If the person is standing, this is easy to spot. But if you’re sitting across from someone at a table, this sign can be hidden from view and easy to miss—so try purposely dropping your pen on the floor and then picking it up to do some detective work.

Too fast or too slow. I’m sure you’re already on the lookout for the sudden onset of stuttering, mumbling, throat clearing, hard swallows and/or a pinched voice—all well-known signs that someone is having trouble with the truth. But you would be wise to also pay attention to the speed at which someone talks. If it suddenly changes—speeding up or slowing down for no apparent reason—watch out.

The eyes don’t have it. You have undoubtedly noticed that some people’s smiles seem fake while others’ seem genuine. What is it, specifically, in the smile that makes the difference? Dr. Salem noted that it’s all about the eyes—so focus on them. If a person’s smile is wide at the mouth but doesn’t make his or her eyes crinkle and light up, then he or she is most likely faking the emotion of happiness—and therefore potentially faking whatever he or she is saying to you.

Also pay attention to how long a smile lasts—a fake smile fades the fastest. (Now, of course, if the person speaking to you has gotten Botox injections, this red flag is much harder to notice—pay closer attention to the other warning signs instead!)


There are some people who are quite accomplished at lying and can display normal body language right in the middle of telling you a whopper. But you do have another important defense against this—your gut instincts. As Dr. Salem pointed out, your mind processes information more quickly than you can articulate it, and your intuition is not just guesswork—it is the invaluable compilation of a lifetime of experiences that your mind unconsciously taps into to make a more informed judgment. You might not even be able to explain your suspicions to yourself, let alone anyone else. But if your instincts tell you that something is wrong, don’t ignore it. It may not be a red flag but, let’s say, a yellow one. Meaning: Proceed with caution.