Here's exactly how I spot a liar, says ex-CIA officer: It can be very 'revealing'

In my work as a CIA analyst, and now as a CEO, reading people and navigating complex social dynamics is central to everything I do. And spotting a liar is not always as easy or obvious as we might think.

There is no physical response linked to lying. Some people are more nervous than others. Or they have a hyper-developed sense of guilt that causes them to behave in ways that only seem "guilty," at the suggestion that they did something wrong, even when they didn't.

That's why polygraph tests are inadmissible in court. They measure physiological stress — heart rate, sweating, breathing — not deception. Anxiety, fear and nervousness can all cause false positives in a polygraph test. 

So if lie detectors can't detect lies and "tells" like fidgeting or evasive eye contact don't reveal much, how do you actually catch a liar? 

"Trust, but verify" is a big motto at the CIA. To build a complete picture of someone's trustworthiness, we collect information from a variety of sources and monitor their behavior and reliability over time. 

You can do this on both a personal and professional level. Gather information from friends, colleagues and social media profiles, and start to build a profile.

I do this whenever I meet a new client or partner. I will start with a baseline level of trust and continue to evaluate them at regular intervals. 

We don't always have time to verify someone's trustworthiness over multiple interactions. 

Sometimes we have to make a one-off judgment call. Even without the benefit of time, you can still collect key information in the moment by asking yourself these questions:

1. What is the worst thing that can happen if this person is lying? If I make the wrong call, is this a price I'm willing to pay?
2. Does this person have ulterior motives that benefit them, at a cost to me?
3. Are they a qualified expert or have relevant experience on this topic? 
4. Can I objectively verify or disprove what they are saying?
5. Are they creating a false sense of urgency?

That last question can be revealing. Very little, if anything, needs to be decided on the spot. Don't let someone else's agenda force you into a fast decision that is not in your best interests. 

When you can't determine if someone is trustworthy, an underrated strategy is to move slowly. Glean more information by getting a sample size of what this person has to offer.

For example, you might need a new supplier for your company. If they promise you the world but are untested and unfamiliar to you, don't give them a big contract. Try one small order first and see how things go.

We already do this all the time without realizing it. This is why we go on multiple dates with potential partners and don't jump straight to marriage after a positive first impression.

With interactions that are hard to read, taking smaller steps can help you protect yourself.

If you are still unsure if someone is lying and you can't use those first three strategies, the best thing you can do is say "no" and move on. When in doubt, don't.

Having a baseline sense of trust is great, but we shouldn't fall for myths about how to read others either. Ask questions. Analyze the objective data. Build a picture over time. And trust, but verify.

Rupal Patel is the founder and CEO of the Global Leadership Lab. As an analyst and officer at the CIA, she advised four-star generals and earned war zone service medals. She is the author of "From CIA To CEO: Unconventional Life Lessons for Thinking Bigger, Leading Better and Being Bolder."

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