When I show audiences how to “read the room” by understanding subtle nonverbal cues, I’m often asked if there are specific signals that prove someone is lying. The answer may surprise you: At this point,  no one and no technology can definitively detect a lie 100% of the time.

For example, polygraphs are only about 85% accurate, which is why they are not admissible in court. Research has revealed that most people – even experts – are only about 50% accurate in detecting a lie.

Little white lies are harder to detect.

“Does this outfit make me look fat?” Humor columnist and author Dave Barry once said that if your spouse asks you this question, the best response is to fake a heart attack. Most people avoid a 911 call by simply telling what’s known as “a little white lie.”

One reason people are rarely caught when telling a little white lie is that the person hearing the lie wants to believe it. The other reason is this type of lie does not usually cause the teller much stress.

The intention is a good one – not to hurt someone’s feelings – so the teller usually will not show any stress signals. And let’s face it, there are no harsh consequences to being caught in that lie. Nobody is going to jail for trying to spare someone’s feelings, so again, the teller is not under stress.

What about when someone faces big consequences if they are caught lying? In those cases,  they are more likely to show nonverbal stress signals. The problem is that people who are telling the truth may also show stress signals when being accused or scolded for something they didn’t do.

A stress signal is NOT the same as a lie signal.

In law enforcement, the most dangerous liars are the least likely to give it away. My mentor Joe Navarro shared with me that psychopaths and sociopaths don’t show stress when they lie because they have no feelings of guilt around it.

So, what can you do? While it is hard to detect when someone is lying, there is something that can help you make an educated guess. Look for “Hot Spots.” If there is a change in their norms or a shift in their actions, then ask more questions around the topic that triggered the stress. If someone is sitting with their legs crossed, and suddenly starts kicking the top leg up and down, that could be a sign that something has stressed them out.

Consider both verbal and nonverbal signals to uncover hidden issues.

Pay special attention if someone deflects a question instead of answering it directly. For example: if in response to “Did you take my chocolate?” they say, “Why would I take your chocolate?” That’s an indirect answer that avoids the question. Notice they never said they didn’t take your chocolate. This pattern of not directly answering an accusation was identified when analyzing news interviews of people, who were later convicted of crimes. Before trial, when asked about the accusations, they gave indirect answers rather than say “I didn’t do it.” It’s interesting that people, who are found guilty of much more serious crimes, made considerable efforts to avoid telling a direct lie.

If you want to learn more about reading nonverbal stress signals and myth-busters about detecting lies, go to my book site at https://readthezoom.com