As an Intelligence Operative, identifying deception was part of my job. One wrong call could cost me my life. In fact, despite all my former training and experience, I nearly did lose my life on a couple of occasions.

Fortunately, there is significant science behind deception. Through experience, wisdom, training and lots of practice, I was able to master the art of recognizing lies and deception. My training extended far beyond listening to “gut feelings” or intuition, although both were helpful in many scenarios.

Today, it is possible for anybody to learn the signs of deception. In fact, it is my job to help individuals like you to reliably identify deceit and lies.

The first step to identifying deception is to “baseline.”

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Baseline

In my line of work, I was often introduced to dubious characters. As a result, I had to take many precautions. One of my first lines of defense was baselining.

To baseline, you need to gauge how your subject behaves typically when they’re not confronted with stress or feel uncomfortable. This gives you a standard to compare their future reactions against.

While baselining, it is critical to actively listen. Actively listening means being fully engaged with your speaking partner. Active listening does not mean actively preparing a response or becoming distracted. It involves focusing and clarifying questions.

Active listening will allow you to capture information from a person that you would miss through passive listening. This additional information can provide you with invaluable information and insights into another person’s mind. Actively listening will also help you baseline as you mentally note a person’s regular vocal patterns, volume, and pitch.

You can also find your subject’s baseline by watching them closely. Pay attention to the person’s eye movements, blinking rate, dry mouth, abnormal normal hand or foot gestures and micro-expressions. Every single one of these subtle cues would become revealing and valuable intel into what was going on inside the mind of the person I was speaking with.

Related: 10 Telltale Phrases That Indicate Somebody Isn’t Telling the Truth

Important microexpressions and body movements

Have you ever noticed a poker player wearing glasses? If so, you can bet that this poker player understands that eyes can be a dead giveaway. Certain things happen to the eyes under stress, and we can do nothing to prevent these reactions. Examples include dilation blink rate and visual accessing cues.

After you have baselined, you can look for abnormalities in your subject’s eye movements. You should also take a closer look at any other changes in your subject’s body movements and microexpressions.

For example, I often pay attention to people’s lips. According to psychologist and author David Matsumoto, lips are a type of microexpression. They can be very revealing as to what’s going on in the side inside of a person’s mind.

For instance, a person at ease will usually have loose or parted lips. However, if a person’s lips randomly retract and disappear, this might indicate discomfort. Tight or pursed lips could signify anger, and trembling lips often denote strong emotions like sadness or fear.

When I see these changes happen, I make it my job to extract further information. I do this by asking further questions and inviting them to continue speaking. Then, I observe their reactions carefully.

Related: 7 Ways Body Language Speaks Louder Than Words

Changes in hand and foot movements, or fidgeting, can also provide subtle clues into what a person tries to hide. These motions may indicate that a person is hiding an emotion or, in my case, a weapon.

I would also closely observe the breath rate of my targets. If someone is breathing heavier or deeper than normal, you might need to investigate why. Nostrils are interesting to watch as well. Nostrils flare, indicating the person is taking in more oxygen. This can indicate that a person is getting ready to run or attack.

Finally, another interesting facial gesture to observe is the forehead. A wrinkled forward is a common subconscious reaction from someone trying to manipulate while looking innocent. It’s important to note that these are all biological responses that humans do instinctively. Deviations would be cause for suspicion.

Related: How to Detect a Liar in Seconds Using Nonverbal Communication

In conclusion

Detecting liars does take study and hard work. It is a craft and an art form that requires practice. As you continue to learn more, remember that compulsive liars or habitual liars eventually believe their own lies. This makes detecting deception stress or other variances from their normal behavior much more difficult. Be patient, and do not stop practicing.

Remember, if you are uncertain that a person is dealing with you honestly, you have a right to know. Be sure to observe and, if appropriate, ask more questions to seek further clarity.

Finally, while your job might not include questioning criminals or terrorists, it is important to be aware of deception in business. Having a few tools up your sleeve will allow you to make smarter business partnerships and decisions.