How do you know if someone is lying or telling you the truth? Is it a gut instinct, or is everyone telling the truth until proven guilty by their mannerisms? On average, every American lies once to twice a day.
It’s important to recognize that most “tell-tale” signs of lies also characterize people who are nervous or anxious. How someone acts and projects themselves when they are undoubtedly comfortable and telling the truth is known as their truth baseline. Excessive mannerisms would then indicate a lie.
To grow a sense of when a specific person is lying, you need to find their truth baseline. Ask them easy questions such as where they want to vacation, a question that they have no reason to lie about, then ask a more uncomfortable question. FBI agents look at people’s social media accounts to learn information about what that person finds to be comfortable and uncomfortable topics to talk about.
Once you think that you know their truth baseline, ask them a question that they would lie about, and ask them the same question in three different ways. Notice if there are any discrepancies in their answers or if it’s perfectly scripted. Do they sound like a politician trying to convince you to vote for them or back a policy? Notice what speed they answer the question. A quick answer return often proves that they had a story rehearsed.
Here are five mannerisms that are general signs that often indicate when someone is lying.

Hand gestures are delayed. Most people make some sort of hand gesture as they tell a story, but if someone is making up a story, their brain is occupied with making the story and calibrating the level of believability it is so regular hand gestures become delayed.
Unusual gestures such as fidgeting, rocking back and forth, or itching are a sign that someone is lying. Movies and TV shows often dramatize fidgeting in lying characters, but it may be more difficult to detect in real life.
Watch their eyes. If they’re telling a crucial part of the story and they aren’t looking at you, their eyes dart in a different direction, or they stare at something deeply while they’re talking, they’re probably lying.
Sweating. It’s a classic example. If you’re watching someone sweat as they tell you their story, they’re under stress. They’re both spinning a lie and worried about if the receiver of the story is believing them.
The tone of their voice changes as well. A lot of people’s voices become high-pitched or they start yelling if you ask them a question. If you ask them a reasonable question and they raise their voice, they’re defensive because they think that they’re on to you.

Watch this video to figure out if you’re a human lie detector.

Watch students tell stories or facts about themselves. Pay close attention to see who you think is telling the truth.

Test your skills by telling us who you think is lying. Do you have what it takes to find the truth?