I'm a Human Lie Detector — You Can Be Too If You Learn to Read These 5 Facial Expressions Want to get better at negotiations? An expert in reading facial expressions shares her best tips.

My clients often refer to me as a human lie detector because I can read microexpressions and see what people are feeling at the exact moment they feel it.

Microexpressions are the fleeting, involuntary facial expressions that precede the thought process. They are universal and hardwired into humans and present on our faces regardless of age, gender, culture or geographic location. Even someone well-trained can't mask their facial tells — unless they change their thoughts.

Related: This Body-Language Expert's 'Triangle' Method Will Help You Catch a Liar in the Act

I have spent two decades working as a strategic advisor, and my ability to see what all parties in a meeting are feeling has made me an excellent resource for my clients, both in negotiations and in communicating effectively with various stakeholders.

Now I train other professionals how to read microexpressions using a simple and systematic methodology that I developed while living abroad for 25 years in nine countries and studying eight languages through immersion. This easy-to-absorb approach works especially well for people in power who have limited time and want immediate takeaways.

Here are five microexpressions to look for in negotiations to make you a human lie detector yourself.

1. The NO Face

In any negotiation, pay attention to when the other party shows that they don't like something. Recognizing this allows us to pivot and adjust. The NO face has three parts:

1. Squishy wrinkles on the sides of the nose

2. Pulling up the upper lip

3. Deep shadows on the sides of the nostrils

In the microexpression of NO, we usually just see the nose wrinkles and the nostril shadows twitch on one side, like a bunny rabbit wiggling its nose. Because this motion can last only a fraction of a second, plant your gaze on the lower part of the face when you come to a pivotal part of the negotiation or pitch. Note: Don't keep your gaze fixed on the mouth area for more than three seconds, because this could send a signal to the other person that you want to kiss them, and that's an entirely different discussion!

2. Holding Back

This facial expression is the equivalent of biting our tongues. Think of it as the "I have something to say but don't think it's the right time or place to say it" expression. If you see this expression in a meeting, the person showing it will likely tell you what they are holding back when you get them away from the group… because they are already itching to say it.

This gives you a chance to build a connection by presenting the person with an opportunity to talk about something important to them. Holding back shows in a bubble underneath the lower lip. This expression looks like someone's taken a pinch of chewing tobacco and placed it between their lower lip and their bottom teeth. It's not technically a microexpression because it takes a lot of muscles to twist your face into this position, and as such is usually held for a longer duration.

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

3. Joy (the YES Face)

The most important part of the expression of Joy is the rise of the cheeks, and the easiest place to see if the cheeks have risen is in the area under our eyes. Normally the skin in this area is flat; however, when the cheeks rise, it bulges because it has nowhere else to go. I call these bulges "smile bags." If you see a person with smile bags in a negotiation, they like what was just said. Seeing that someone is enthusiastic about where you're going in a conversation gives you an opportunity to close your deal or possibly expand your ask.

4. Oh Crap!

"Oh crap!" is what I call the microexpression of fear. In this expression, a person pulls one corner of the mouth diagonally down toward the respective shoulder, often while making a reverse hissing sound. We make this face when we're worried about something that could potentially happen — it's a piece of anticipatory anxiety.

I've seen this expression many times in M&A deals. For example, if one party says, "I want to make sure the technology will be ready for market in the next six months," and the other party says, "Absolutely!" while making this microexpression, there's a problem. The person making the expression doesn't believe what they are saying, and more investigation is needed.

Related: Use This Secret Military Trick to Tell if Someone Is Lying

5. Maybe

The "maybe" face pulls both lip corners down at the same time with closed lips. It looks like a child has drawn a big frown on the face, and it often comes with a shoulder shrug. Some people believe this expression indicates disbelief, but I disagree. It means, "Maybe… I'm not yet convinced, but I could be." If you're in a sales pitch and someone makes this expression, you're not finished convincing them that your solution will meet their needs — more work is needed.

If you want to learn more than 30 facial expressions and test yourself with photographs, see my book, The Facial Expressions Glossary. If you're interested in learning facial expressions in the ultimate anti-textbook, check out my autobiographical book, Diary of a Human Lie Detector: Facial Expressions in Love, Lust, and Lies.

Learning to read facial expressions helps us learn what works and what doesn't work when communicating with others and solving problems together. Ultimately, this improves our ability to connect, both in our business and personal lives.